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2018 Fall Meeting



Nanomaterials- electronics & -photonics

This symposium will cover: 

(i) Nanomaterials Synthesis: From 0D, 1D, 2D, and 3D, Multifunctional Hybrids.

(ii) Investigations: Structures and Properties, Analytical and Computational Modelings.

(iii) Applications: (a) Electronics- Gas/Pressure/Chemical/Biological Nanosensings, (b) Photonics/Plasmonics/Photovoltaics/Lightening Technologies, (c) Energy/Piezotronics/Green Energy (e) Photocatalysis, Water Purification, (f) Biomedical Nanomaterials, (g) Advanced technologies.


Nanostructures, particularly from the inorganic metal oxides, organic, carbon, polymer, etc. family, are very important material candidates because of their surface-to-volume ratio and morphology-dependent extraordinary properties suitable for various advanced technologies. The ongoing deployments in the direction of 0D (quantum dots), 1D (hybrid nanowires), 2D (from new semiconductors) and 3D networked materials have further become very relevant towards various applications, due to their excellent nanoscale features and their simplicity of utilization. Due to their compact synthesis forms, they can be easily handled or integrated in the desired manner in devices or sensors. The 0D, 1D, 2D nanostructures from noble metals (Au, Ag, Cu, etc.) have found immense applications in sensing, biomedicine, waveguides and telecommunication, etc. Nanostructures from metal oxides are very interesting (fundamental as well applied) materials due to their bandgap position (intermediate between metals and insulators), suitable for various advanced technologies. When these metal oxides and metals are combined in hybrid nanomaterials, they further become very relevant in terms of understanding the properties and, consequently, advanced applications. The carbon nanostructure family, i.e., fullerenes, CNTs (MWCNTs), graphene, graphene oxide (GO), etc., have shown very strong potential ranging from fundamental properties to advanced energy applications. Hence they have been the subject of huge research attention in the last couple of decades. Recent developments in the direction of 3D carbon networks have opened an entirely new dimension in nanotechnology research. Research on 3D soft ceramics, from metal oxides interconnected networks, which is currently in the main stream research focus, is very important, because it can bring towards nanotechnology-related applications in real life.                    

Appropriate growth strategies of different structures (0D, 1D, 2D and 3D) using simple methods, understanding their properties, their applications in different directions, etc. are still key issues. Interdisciplinary research platforms are required, equipped with: (i) synthesis groups for developing different nanostructures, (ii) theoretical/computational frameworks to model/analyze/simulate towards a better understanding of structure-property relations, and (iii) application experts, who can accordingly utilize these materials in various applications, which will be actually the main aim of the proposed symposium.

Hot topics to be covered by the symposium:

  • Hybrid Metal Oxide Materials (0D, 1D, 2D, 3D): Synthesis & Characterizations, Structure-property relations, Analytical/Simulation studies, Applications: Electronics-Chemistry-Energy-Sesning-Lightening-Biomedical-Environmenta - Applications;
  • Plasmonic Nanostructures: Synthesis & Characterization, Computational Modeling, Sensing and Nanophotonics Applications;
  • Carbon Family (Fullerenes to 3D graphene): Fabrication & Characterizations, Structure-property relations, Simulations studies, Applications: Nanoelectronics-Sensing-Supercapacitor-Batteries-Energy;  
  • Quantum Dots: QDs are recently gaining huge interests and one session of the symposium will be devoted to only QDs;
  • Perovskites: QDs, NCs, nanowires, thin films, synthesis and applications;
  • Synchrotron radiation/Ion beam-based material characterization and engineering.

List of invited speakers:

  • Quinten Akkerman, IIT Genoa, Italy
  • Yehonadav Bekenstein,  University of California Berkeley, USA
  • Maryna Bodnarchuk, EMPA Dübendorf, Switzerland
  • Elke Debroye, KU Leuven, Belgium
  • Lioz Etgar, The Hebrew University of Jerusalem, Israel
  • Jacky Even, CNRS Institut FOTON, Rennes, France
  • Sreetosh Goswami, NUS, Singapore
  • Xuemei Han, Nanyang Technological University, Singapore
  • Utkarsh Jain, Amity University, India
  • Sher Lin Charlynn Koh, Nanyang Technological University, Singapore
  • Maksym Kovalenko, ETH Zurich, Switzerland
  • Xuanhua Li, Northwestern Polytechnical University, China
  • Yih Hong Lee, Nanyang Technological University, Singapore
  • Efrat Lifshitz, Technion-Israel Institute of Technology, Israel
  • Sören Madsen, Aarhus University, Denmark
  • Giovanni Mattei, Padova University, Italy
  • Sara Núñez-Sanchez, University of Vigo, Spain
  • Silvio Osella, University of Warsaw, Poland
  • Gabriele Raino, ETH Zurich, Switzerland
  • Andrey L. Rogach, City University of Hong Kong
  • Michael Saliba, Fribourg University, Switzerland
  • Chih-Jen Shih, ETH Zurich, Switzerland
  • Aadesh Pratap Singh, Chalmers University of Technology, Sweden
  • Ashutosh Tiwari, Utah University, USA
  • Alexander S Urban, LMU Munich, Germany
  • Qiao Zhang, Soochow University, China
  • Haizheng Zhong, Beijing Institute of Technology, China
  • Roman Krahne, Istituto Italiano di Tecnologia, Genoa, Italy
  • Brahim Lounis, Univ Bordeaux, Institut d’Optique & CNRS, France
  • Jani Kotakoski, Wien University, Austria

Scientific committee members:

  • Rainer Adelung, Germany
  • Franz Faupel, Kiel, Germany
  • Lorenz Kienle, Germany
  • Carsten Ronning, Germany
  • Horst-Günter Rubahn, Denmark
  • Jörg Hübner, Denmark
  • Amit Bhatnagar, Finland


Selected papers will be published as a special issue in the journal physica status solidi (a) – applications and materials science (Wiley).

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Perovskite : (Session Chairs: Y. K. MISHRA, L POLAVARAPU)
Authors : Andrey L. Rogach
Affiliations : Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong

Resume : Chemically synthesized lead halide perovskite nanocrystals have emerged as a new class of efficient light emitting materials. High emission quantum yield, easily tuned emission colors, and high color purity make this class of materials particular attractive for light-emitting devices (LEDs) and display applications. I will review our recent synthetic strategies leading to highly luminescent CH3NH3PbX3 and CsPbX3 (X = Cl, Br or I) perovskite nanocrystals of different sizes and shapes, focusing on the elucidation of mechanism of their nucleation and growth, as well as methods to improve their stability in humid/aqueous environment. I will further consider the interface engineering of perovskite nanocrystal based hybrid films, which allows us to use them as phosphors in down-conversion LEDs, and in charge injection electroluminescent devices.

Authors : Maksym V. Kovalenko
Affiliations : 1. ETH Zürich, Department of Chemistry and Applied Biosciences, CH-8093, Zurich, Switzerland 2. Empa-Swiss Federal Laboratories for Materials Science and Technology, CH-8600, Dübendorf, Switzerland

Resume : We review the important differences that exist in the chemistry and physics of colloidal lead halide perovskite nanocrystals (APbX3, NCs, A=Cs+, FA+, FA=formamidinium; X=Cl, Br, I) as compared to conventional semiconductor NCs made of metal pnictides and chalcogenides. We survey the the synthesis methods, optical properties and prospects of these NCs for photochemical and optoelectronic applications [1, 2, 3]. The absorption spectral, sponaneous and stimulated emission spectra of these NCs are readily tunable over the entire visible spectral region of 400-800 nm by composition as well as by the NC size and shape [4-5]. The photoluminescence of these NCs is characterized by narrow emission line-widths of 100 meV (12-45 nm from blue-to-near-infrared), wide color gamut covering up to 140% of the NTSC color standard, high quantum yields of up to 100%. Cs- and FA-based perovskite NCs are highly promising for luminescence downconversion (bright and narrow emission at 530 and 640 nm needed in backlighting of LCD displays or for light-emitting diodes). With a new ligand capping strategy utilizing common and inexpensive long-chain zwitterionic molecules such as 3-(N,N-dimethyloctadecylammonio) propanesulfonate, a much better chemical durability can be attained [6]. In particular, high purity colloids are ideal for further engineering as needed for photochemical/photocatalytic applications. For the industrial-scale, inexpensive production, we present a simple mechanochemical synthesis of perovskite NCs using wet ball-milling [7]. 1. M. V. Kovalenko et al. Science 2017, 358, 745-750 2. Q. A. Akkerman et al. Nature Materials, 2018, 17, 394–405 3. M. V. Kovalenko et al. CHIMIA, 2017, 71, 461-470 4. L. Protesescu et al. Nano Letters 2015, 15, 3692–3696 5. L. Protesescu et al. ACS Nano 2017, 11, 3119–3134 6. F. Krieg et al. ACS Energy Lett., 2018, 3, 641–646 7. L. Protesescu et al. ACS Appl. Nano Mater., 2018, 1, 1300–1308

Authors : Jacky Even
Affiliations : Univ Rennes, INSA Rennes, CNRS, Institut FOTON - UMR 6082, F-35000 Rennes, France

Resume : In the past six years, solution-processed organometallic perovskite based solar cells have emerged as a promising thin-film photovoltaic technology. Presently, the intended applications of this class of 3D materials are in the realm of conventional semiconductors. Halide perovskite colloidal nanocrystals and multilayered crystals have attracted attention more recently in 2015 and 2016 for light emission applications but also photovoltaics. The presentation will review recent theoretical and experimental results on colloidal nanocrystals and multilayered crystals, with a special focus on excitonic properties, exciton fine structure, quantum and dielectric confinements

Perovskite : (Session Chairs: Y. K. MISHRA, L POLAVARAPU)
Authors : Michael Saliba
Affiliations : Adolphe Merkle Institute, University of Fribourg

Resume : Perovskites have emerged as low-cost, high efficiency photovoltaics with certified efficiencies of 22.1% approaching already established technologies. The perovskites used for solar cells have an ABX3 structure where the cation A is methylammonium (MA), formamidinium (FA), or cesium (Cs); the metal B is Pb or Sn; and the halide X is Cl, Br or I. Unfortunately, single-cation perovskites often suffer from phase, temperature or humidity instabilities. This is noteworthy for CsPbX3 and FAPbX3 which are stable at room temperature as a photoinactive “yellow phase” instead of the more desired photoactive “black phase” that is only stable at higher temperatures. Moreover, apart from phase stability, operating perovskite solar cells at elevated temperatures (of 85 °C) is required for passing industrial norms. Recently, double-cation perovskites (using MA, FA or Cs, FA) were shown to have a stable “black phase” at room temperature. These perovskites also exhibit unexpected, novel properties, e.g., the Cs/FA mixtures supress halide segregation enabling band gaps for perovskite/silicon or perovskite/perovskite tandems. Adding more components increases entropy that can stabilize unstable materials (such as the “yellow phase” of FAPbI3 that can be avoided using the also unstable CsPbI3). Here, we take the mixing approach further to investigate triple cation (with Cs, MA, FA) perovskites resulting in significantly improved reproducibality and stability.

Authors : Prof. Lioz Etgar
Affiliations : The Hebrew University of Jerusalem, The Institute of Chemistry, Casali Center for Applied Chemistry, Jerusalem, Israel

Resume : Perovskite is a promising light harvester for use in photovoltaic solar cells. In recent years, the power conversion efficiency of perovskite solar cells has been dramatically increased, making them a competitive source of renewable energy. This work will discuss new directions related to two-dimensional organic inorganic perovskite bulk and nanostructures and their applications. In low dimensional systems, stability of excitons in quantum wells is greatly enhanced due to the confined effect and the coulomb interaction. The exciton binding energy of the typical 2D organic-inorganic perovskites is up to 300 meV and their self-assembled films exhibit bright photoluminescence at room temperature.  In this work we will show the dimensionality in the perovskite structure. The 2D perovskite structure should provide stable perovskite structure compare to the 3D structure. The additional long organic cation, which is added to the perovskite structure (in the 2D structure), is expected to provide hydrophobicity, which will enhance the resistivity of the perovskite to humidity. Moreover we will demonstrate the use of 2D perovskite in high efficiency and high voltage solar cells.  Organometal halide perovskite is used mainly in its “bulk” form in the solar cell. Confined perovskite nanostructures could be a promising candidate for efficient optoelectronic devices, taking advantage of the superior bulk properties of organo-metal halide perovskite, as well as the nanoscale properties. In this work, we present facile low temperature synthesis of two-dimensional (2D) lead halide perovskite nanorods (NRs). These NRs show a shift to higher energies in the absorbance and in the photoluminescence compared to the bulk material, which supports their 2D structure. In addition, by alternating the halide composition, we were able to tune the optical properties of the NRs. By varying the ligands ratio (e.g. octylammonium to oleic acid) in the synthesis, we were able to provide the formation mechanism of these novel 2D perovskite NRs.  The quest for novel perovskite compositions in the nano-scale is significantly important. This work reports on a mixed-cation system of RbxCs1-xPbX3 (where X=Cl or Br) nanoparticles. The absorption of the nanoparticles is tunable in the near ultra-violet and visible regions between ~ 395-525 nm for RbxCs1-xPbX3 (x=0 to x=0.8 and X=Cl or Br). The photoluminescence quantum yields (PLQY) of the mixed Rb+/Cs+ nanoparticle systems are comparable to the PLQY of CsPbX3 nanoparticles. Interestingly the attempt to synthesize Cl- and Br-based nanoparticles with high Rb+ content succeeded, although possessing low tolerance factors. We conclude that these mixed Rb+/Cs+ nanoparticles are more adjustable to structural distortions caused by the cation substitutions than their bulk counterparts, what opens a way towards developing more advanced mixed-ion perovskite compositions in the nano-scale.

Authors : Maryna I. Bodnarchuk, Ivan Infante, Maksym V. Kovalenko
Affiliations : Empa-Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland ETH Zürich, Department of Chemistry and Applied Biosciences, CH-8093 Zurich, Switzerland Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling (ACMM), VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands

Resume : Colloidal organic/inorganic lead halide perovskite nanocrystals (NCs) are intensely pursued as highly promising, low-cost light-emitting materials with wide color gamut. These NCs exhibit unprecedented luminescent properties – narrow-band emission with high quantum efficiency, covering the whole visible spectral range and extending into near-infrared, all obtained without epitaxial overcoating of the NC surfaces for electronic passivation of the surface states. Despite the superior optoelectronic properties found in fundamental studies, building efficient and long-lasting devices from perovskite NCs remains a challenge: the unstable composition, related to its ionic core, combined with the labile ligand binding lead to structural degradation; it complicates the post-synthesis purification process, limits the possibilities for ligand exchange, and reduces the colloidal stability. Surface and sub-surface atoms are likely directly involved in all possible chemistry equilibria and transformations. Controlling NC surface structure is therefore paramount for mitigating these instabilities. We identified the most probable aging mechanism in perovskite NCs and propose a general surface reconstruction and ligand coating strategy for increasing colloidal stability and for eliminating traps. The experimental findings are corroborated by the electronic structure calculations using density functional theory. In practical terms, we demonstrate that such an approach is useful to obtain purified CsPbBr3 NCs samples, washed up to three times in several solvents, with near unity photoluminescence quantum yields and long-term colloidal stability.

Authors : G. Rainò, M. A. Becker, M. I. Bodnarchuk, R. F. Mahrt, T. Stöferle and M. V. Kovalenko
Affiliations : - Institute of Inorganic Chemistry, Department of Chemistry and Applied Bioscience, ETH Zurich, 8093 Zurich, Switzerland. - Laboratory of Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland. - IBM Research – Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland

Resume : Besides conventional optoelectronic devices (LEDs and laser), colloidal nanocrystals (NCs) are pursued as non-classical light sources (i.e. single photon emitters) that might play a pivotal role in future quantum technologies, such as quantum cryptography and quantum sensing. Due to strongly reduced charge trapping on surface states, perovskite NCs become attractive as alternative quantum light sources. Fully inorganic caesium lead halide (CsPbX3, where X=Cl, Br, I) perovskite NCs are characterized by narrow emission lines, obtain ultrahigh photoluminescence quantum yields of up to 90% and are tuneable over a wide energy range [1]. At the single NC level, they exhibit stable, blinking-free emission at cryogenic temperatures [2]. An in-depth investigation of the trion dynamics revealed the absence of non-radiative quenching processes, such as Auger recombination, even without any shell passivation. We examined the origin of the composition dependent ultrafast (sub-ns) radiative recombination dynamics, and assign it to a giant oscillator strength transition. For CsPb(Br/Cl)3 NCs the radiative lifetime is in the order of 200-250 ps, representing a significant enhancement compared to other colloidal II-VI NCs or organic molecules. Using polarization dependent high resolution spectroscopy, we further elucidated the complex nature of the exciton fine structure splitting revealing the unique character of bright triplet excitons [3]. When organized in highly ordered three-dimensional superlattices, perovskite NCs exhibit superfluorescence (SF), a cooperative emission of individual emitters that arises due to a coherent collective coupling to a common light field, leading to strongly enhanced radiative rates. In addition, extension of first-order coherence time by more than a factor of four together with photon bunching and Burnham-Chiao ringing behaviour at high excitation densities are key observed features that characterize SF [4]. Our results demonstrate a solid state approach for the generation of superfluorescent Dicke states with the potential for on-chip optical and electrical control. Furthermore, these mesoscopically extended coherent states might enable the generation of entangled N-photon bundles for quantum information processing and quantum sensing applications. References: [1] L. Protesescu et al., Nano Letters (2015), 15, 3692–3696. [2] G. Rainò et al., ACS Nano (2016), 10, 2485–2490. [3] M. Becker et al., Nature (2018), 553, 189–193. [4] G. Rainò et al., submitted (2018), arXiv:1804.01873.

Perovskite : (Session Chairs: Y. K. MISHRA, L POLAVARAPU)
Authors : Brahim Lounis
Affiliations : Univ Bordeaux, Institut d’Optique & CNRS, LP2N F-33405 Talence, France

Resume : Spectroscopically resolved emission from single perovskite nanocrystals at cryogenic temperatures provides unique insight into physical processes that occur within these materials. At low temperatures the emission spectra collapse to narrow lines revealing a rich spectroscopic landscape and unexpected properties, completely hidden at the ensemble level and in bulk materials. In this talk, I will discuss how magneto-photoluminescence spectroscopy of single Cesium or Formamidinium lead Bromide (CsPbBr3 or FAPbBr3) nanocrystals at cryogenic temperatures probes the fundamental excitonic structure of the band edge, revealing spectral fingerprints that are highly sensitive to a range of structural and photophysical properties of the nanocrystals. I will also present how the spectra of individual Formamidinium lead iodide (FAPbI3) nanocrystals reveal the optical phonon modes responsible for the emission line broadening with temperature and a vanishing exciton-acoustic phonon interaction in these soft materials. The photoluminescence decays in these nanocrystals are governed by thermal mixing between fine structure states, with a two-optical phonon Raman scattering process. These results point to a strong Frölich interaction and to a phonon glass character that weakens the interactions of charge carriers with acoustic phonons and thus impacts their relaxation and mobility in these perovskites.

Authors : E. Debroye1, H. Yuan1, M. Keshavarz1, J. Steele1, M. Roeffaers2, J. Hofkens1
Affiliations : 1Department of Chemistry, KULeuven, Belgium 2Centre for Surface Chemistry and Catalysis, KULeuven, Belgium

Resume : After seminal reports of their interesting physical properties published in 2009 and 2012 an explosion of scientific interest into metal halide perovskites (MHPs) in the past decade has seen this family of materials emerge as the most exciting avenue for next-generation solar cells. The strong promise for MHP materials arise of course from their fundamental physics; from high absorption coefficients at visible wavelengths, long carrier diffusion lengths and small exciton binding energies, to its simple solution-based processing. Justifiably, an early surge of research activity was inspired by an empirical race to produce photovoltaic devices with ever-higher photo-conversion efficiencies. Consequently, early research saw perovskite engineering significantly outpace the understanding of their physical properties. In response, the focus of researchers is steadily shifting toward the intrinsic properties of perovskites, as these will ultimately define their performance in any photonic application. In this light, recent research in our laboratory aims at connecting the microstructure of perovskite crystals with their physical properties, by addressing three overarching goals: (1) Development of systematic experimental protocols for controlled and reproducible synthesis of a variety of highly crystalline, monodisperse and defect-poor perovskite crystals with well-defined morphology, with sizes from few nm to mm range. (2) Their in-depth investigation using various advanced techniques. (3) Finally, the knowledge base generated will be applied to the development of better-performing photonic devices. Here, I will report recent progress in perovskite synthesis and single particle micro- and spectroscopy.

Authors : Jacek K. Stolarczyk1, Sebastian Rieger1, Bernhard J. Bohn1, Linn Leppert2, Markus Döblinger3, Lakshminarayana Polavarapu1, Jochen Feldmann1
Affiliations : 1. Photonics and Optoelectronics Group, Department of Physics and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität, Amalienstr. 54, 80799 Munich, Germany 2. Institute of Physics, University of Bayreuth, 95440 Bayreuth, Germany 3. Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (E), 81377 Munich, Germany

Resume : Lead halide perovskites possess fascinating optoelectronic properties, but the toxic nature of the constituent lead drives the quest for more benign alternatives. Bismuth-based perovskites are of particular interest because of isoelectronic structure of Bi3+ with Pb2+. In this context, we report here the preparation of Cs3Bi2I9 nanoplatelets with thickness of 8-10nm and lateral sizes up to half a micrometer. We further apply a combination of state-of-the-art DFT calculations and ultrafast spectroscopy studies to elucidate the unusual properties of this material and explain the reasons for its weak photoluminescence. Moreover, we identify a strong excitonic transition in the absorption spectrum and discuss the origin of its large exciton binding energy. The study demonstrates that bismuth-based perovskites offer unique optical and electronic properties, distinct from lead-based counterparts, yet promising for future applications.

Authors : Eva Bladt1, Yu Tong2, Elke Debroye3, Lakshminarayana Polavarapu2, Haifeng Yuan3, Jochen Feldmann2, Johan Hofkens3, Maarten B. J. Roeffaers4, Sara Bals1
Affiliations : 1 Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium 2 Nanosystems Initiative Munich (NIM) Schellingstraße 4 80799 , Munich, Germany 3 Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium 4 Centre for Surface Chemistry and Catalysis, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium

Resume : We investigated two types of perovskites: CsPbX3 and CH3NH3PbX3 (X = Cl, Br, I) nanocrystals (NCs) at the atomic level. The main challenge during these transmission electron microscopy (TEM) investigations is to overcome damage while imaging, as these materials are very sensitive to the electron beam. CsPbX3 nanocubes are studied using high resolution HAADF-STEM and exit wave reconstruction to elucidate on their atomic structure and surface termination. The investigation of their surface termination is troublesome as the degradation of the structures starts at the edges of the cubes. A careful study revealed that the NCs terminate with a Cs-I layer, which suggests that Cs-bound alkyl chains passivate them. Next, the use of HAADF-STEM confirmed the successful one-pot synthesis of CsPbX3 perovskite nanowires. By investigating different time steps, it was proven that these nanowires are formed through oriented attachment of the initially formed nanocubes. The study of CH3NH3PbX3 NCs requires even more care, since they almost instantaneously change upon illumination. A time series of energy dispersive X-ray spectroscopy maps of a CH3NH3PbI3 NC shows a continuous decrease of the iodine peak. A combination of low-dose imaging and a template-matching procedure enabled us to reveal their crystal structure, before any deformation occurred. The perovskite lattice is clearly visible, which shows that the NCs have a crystalline structure with a lattice parameter of ~6.4 Å.

Authors : Sudhir, Kumar; Jagielski, Jakub; Shih, Chih-Jen
Affiliations : Institute for Chemical and Bioengineering, ETH Zurich

Resume : Colloidal perovskite quantum dots are emerging as one of the most promising candidates for next-generation monochromatic light sources that require precise bandgap tunability. In this talk, I will cover: (i) the new physical mechanisms in perovskite quantum dot solids: the aggregation-induced emission (AIE) and the delayed radiative energy transfer (DRET); (ii) opportunities of perovskite quantum dots in LEDs: active and downconversion designs; and (iii) challenges in particular concerning electrical stability.

Authors : Yehonadav Bekenstein1, 2, Nanjia Zhou3,4, Carissa N. Eisler1, 2, Peidong Yang1,2, Jennifer A. Lewis*3,4 A. Paul Alivisatos*1,2,5
Affiliations : 1 Department of Chemistry and Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States. 2 Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States. 3 chool of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, United States. 4 Wyss Institute for Biologically Inspired Engineering Harvard University, Cambridge, MA, 02138, United States. 5 Kavli Energy NanoScience Institute, Berkeley, California 94720, USA

Resume : Semiconducting nanowires possess unique anisotropic optoelectronic properties arising from quantum and dielectric confinement effects, making them attractive candidates for a wide range of electronic and photonic applications. The ability to precisely pattern one-dimensional nanomaterials with controlled spatial orientation into planar and 3D structures that exhibit highly anisotropic properties would open new avenues for the integrated design and assembly of optoelectronic devices. Towards this goal, we created stable nanocomposite inks composed of brightly emitting colloidal cesium lead halide perovskite (CsPbX3, X = Cl, Br, and I) nanowires suspended in a polystyrene-polyisoprene-polystyrene block copolymer matrix. Using direct ink writing, we programmably controlled the nanowire alignment within these matrices to produce photonic nanocomposites that exhibit highly polarized absorption and emission properties. Using this approach, we created several device motifs for optical storage, encryption, sensing, and full-color displays as exemplary demonstrations. The polymer encapsulated perovskite nanowires exhibit increased stability towards air and moisture degradation process, suggesting the methods and materials we use can be implemented in future devices.

Authors : Q. A. Akkerman, Liberato Manna
Affiliations : Nanochemistry Department, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, Via Dodecaneso 31, 16146 Genova, Italy

Resume : Lead halide perovskites (LHPs) nanocrystals (NCs) have attracted the attention of diverse materials scientists due to their unique optical versatility, high photoluminescence quantum yields and facile synthesis.1, 2 LHP NCs have a ‘soft’ and predominantly ionic lattice, which allows for synthesis chemistry that differs strongly from that of conventional NCs. This ionic lattice for instance allows for fast room temperature synthesis of LHP NC inks, rapid anion exchange, and high levels of alloying.3-5 Here, we will present a recent work exploring this peculiar ionic LHP lattice, allowing for the synthesis of alternative LHP phases and “switching” between them.6 Cesium LHP can also crystalize the Cs4PbX6 structure, where the PbX64- octahedra are completely decoupled in all dimensions. While the cesium LHP NCs are widely studied and well understood, Cs4PbX6 NCs are rather unknown and understudied. We report a fast synthesis method for highly monodispse 9-37nm Cs4PbX6 (X=l,Br,I) NCs.6 These NCs have large band gaps (> 3.2 eV), and their optical absorption spectra are characterized by narrow excitonic absorption bands, independent of the size of the NCs. Interestingly, these Cs4PbBr6 NCs can be transformed into highly luminescent CsPbBr3 NCs via an insertion reaction with PbBr2. Furthermore, these CsPbBr3 NCs can be transformed back into Cs4PbBr6 NCs via extraction of Pb2+.7 This opens up a reliable post-synthesis method to switch between Cs4PbX6 and CsPbX3 and for the fabrication of novel NC compositions. 1.Protesescu, L. et al. Nano Lett. 15, 3692-3696 (2015) 2.Akkerman Q. A. et al. Nat. Mater, 17, 394–405 (2018) 3.Akkerman Q. A. et al. JACS. 137, 10276-10281 (2015) 4.Akkerman Q. A. et al. Nat. Energy 2, 16194 (2016) 5.Akkerman Q. A. et al. ACS Energy Lett. 2, 2183-2186 (2017) 6.Akkerman Q. A. et al. Nano Lett. 17, 1924-1930 (2017) 7.Akkerman Q. A. et al. J. Phys. Chem. Lett., 9, 2326–2337 (2018)

Symp K:Poster Session (KP) : (Session Chairs:Y. K. MISHRA, L. POLAVARAPU, J. ADAM, M. ELBAHARI, D. K. AVASTHI)
Authors : Dr. Adnan Younis
Affiliations : School of Materials Science and Engineering, University of New South Wales, Sydney, 2052, NSW, Australia

Resume : Abstract Resistive switching devices are promising alternative to existing memories which may offer a potential leap beyond the limits of Flash memories (with respect to write speed, write energies) and Dynamic random access memories DRAM (with respect to scalability, retention times). A conventional RRAM cell is composed of an insulating/dielectric layer sandwiched between two metallic layers. In this talk, an overview of physical and electrochemical processes which may be the origin of the switching phenomenon in various materials will be discussed. Furthermore, novel concepts (strategies) beyond classic doping will be discussed to control device properties like signal to noise ratios and power consumption. In our work, as a first strategy, we realize the superior bipolar resistive switching characteristics of CeO2:Gd-based resistive memory device by utilizing a unusual mean of UV radiation. This non-conventional tool provides us a new degree of freedom to manipulate the performance of a memory device. Our further investigations revealed that the prototype can deliver short term to long term memory transitions which is analogous to the forgetting process of human brain, which is a key biological synaptic function for information processing and data storage. In another strategy, a non-conventional and unique “chronoamperometry” approach contrary to classic voltammetry measurements was implemented to examine the bipolar resistive switching characteristics of ceria based memory cell. Configurable device functionalities such as; categorization of minimum threshold potential to prompt switching behaviour, tuneable on/off ratios with accessible multi-level data storage states can be achieved which are hard to realize in conventional measurement setups.

Authors : Hamid Ullah, Young-Han Shin
Affiliations : Department of Physics, University of Ulsan, Ulsan 44610, Republic of Korea

Resume : The electronic and optical properties of monolayer platinum dichalcogenides family have been investigated using the density functional theory. We found that the PtS2, PtSe2 , and PtTe2 are indirect band gap semiconductor with bandgaps of 2.70 eV, 1.94 eV, and 0.82 eV, respectively. The monolayer platinum dichalcogenides family have strong absorption with very sharp absorption edges, confirming the direct transition from the valence to the conduction band. Their optical absorption spectra show strong optical absorption for these materials is below 4.0 eV, which make them an efficient candidate for solar energy applications. PtS2 and PtSe2 show strongest absorption in the wide range from infra-red to the ultra-violet region of the light spectrum. Furthermore, due to their wider band gap and strong device absorption efficiency make them an excellent candidate for the top cell in the tandem architecture. PtTe2 is considered to be an excellent candidate for bottom cell in the tandem architecture due to its narrow band gap and strong absorption efficiency. Moreover, the band-edge potentials are estimated using Mulliken electronegativity and compared to the redox potential of water to evaluate their possible applications in photocatalysis, we found that PtX 2 family can be used to oxidize H2O into O2 but failed to reduce H+ to H2

Authors : Grzegorz Stando1, Damian Lukawski2, Filip Lisiecki3, Dawid Janas1*
Affiliations : 1 Silesian University of Technology, Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology B. Krzywoustego 4, 44-100 Gliwice, Poland 2 Faculty of Technical Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland 3 Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179, Poznan, Poland

Resume : Carbon nanostructures such as carbon nanotubes (CNTs) and graphene have revealed extraordinary electrical [1], thermal [2] and mechanical [3] properties. As a consequence, they have been envisioned as next-generation materials, which can succeed what we use today. Unfortunately, thin films from nanocarbon materials have a highly hydrophobic character, which narrows down their applications to a significant extent. The most common solution is chemical functionalization, which introduced functional groups to make the material more hydrophilic. That however, leads to weight loss, but, most importantly, significant decrease of the performance. In this contribution, we present how CNT films can be made hydrophilic without any sort of chemical grafting. Single- and multi-walled materials were turned into thin free-standing films and their surface properties were characterized according to a method recently developed by us [4]. Raman spectroscopy, XPS and SEM indicated that the water contact angle of these films can be decreased from 127° to 40° without oxidation [ 5 ]. The presentation will give a preliminary explanation of this unexpected effect. [1] A. Lekawa-Raus, T. Gizewski, J. Patmore, L. Kurzepa, K. Koziol, Electrical transport in carbon nanotube fibres, Scripta Materialia 131, 2017, 112–118. [2] K. Koziol, D. Janas, E. Brown, L. Hao, Thermal properties of continuously spun carbon nanotube fibres, Physica E: Low dimensional Systems and Nanostructures 88, 2017, 104-108. [3] M.-F. Yu, O. Lourie, M. J. Dyer K. Moloni, T. F. Kelly, R. S. Ruoff, Strength and breaking mechanism of multiwalled carbon nanotubes under tensile load, Science 287, 2000, 637-640. [4] D. Janas, M. Rdest, K. Koziol, Free-standing films from chirality-controlled carbon nanotubes, Materials & Design 121, 2017, 119-125. [5] D. Janas, G. Stando, Unexpectedly strong hydrophilic character of free-standing thin films from carbon nanotubes, Scientific Reports 7, 2017, 12274.

Authors : Tomasz Wasiak1, Lukasz Przypis1, Krzysztof Walczak1, Dawid Janas1*
Affiliations : 1 Silesian University of Technology, Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology B. Krzywoustego 4, 44-100 Gliwice, Poland

Resume : 1D nanostructures composed of metals or metal-based compounds are commonly referred to as nanowires. Due to their extraordinary ratio of length to diameter, they often reveal extraordinary properties unlike the bulk materials. As a consequence, the community has focused the efforts to create a big library of these materials ranging from superconducting (YBCO), metallic (Ni, Pt, Au), semiconducting (Si) to isolating (SiO2, TiO2) among others. Nickel nanowires (NiNWs) are particularly interesting due to the fact that they offer very promising properties while the material can be created from inexpensive precursors. Unfortunately, the production of NiNWs of appropriate purity and length/diameter characteristics has been found somewhat troublesome [1,2]. In this contribution we present how NiNWs of tuned diameter distribution can be made using a simple chemical based reduction of Ni ions [3]. Moreover, we found out that the material created using this route has very encouraging catalytic properties [3,4]. A range of chemical transformations carried out with ease using this system will be shown. [1] P. Liu, Z. Li, Mater. Lett., 2009, 63, 1650. [2] Z. Xia, W. Wen, Nanomaterials, 2016, 6, 19. [3] D. Janas, T. Wasiak, L. Przypis, K. Walczak, Chem. Comm. (submitted) [4] T. Siudyga, M. Kapkowski, D. Janas, T. Wasiak, R. Sitko, M. Zubko, J. Szade, K. Balin, J. Klimontko, J. Polański, ChemCatChem (submitted)

Authors : Neetesh Kumar and Jae-Wook Kang
Affiliations : Department of Flexible and Printable Electronics, Polymer Materials Fusion Research Center Chonbuk National University, Jeonju 54896, Republic of Korea

Resume : In this work, Au-MoO3 and Au-WO3 plasmonic nanocomposite thin films have been fabricated using simple, cost-effective and one-step chemical spray-pyrolysis technique. The gold precursor with host precursors was used to deposit Au-transition metal-oxide (Au-TMOs) films on glass substrate. The in-situ grown Au NPs in the host matrix show characteristic plasmon peak due to surface plasmon resonance (SPR) absorption at 600 nm, 550 nm and 575 nm for Au-MoO3, Au-a-WO3 (amorphous) and Au-h-WO3 (hexagonal) films, respectively. The SPR-band exists in the visible and near IR-region (400?1100 nm) of the optical spectrum, which is tuned by increasing the Au loading in the host matrix. The Au-MoO3 and Au-h-WO3 films exhibit strong blue colour in the transmitted light, while Au-a-WO3 films exhibit the purple colour which converted into the dark blue colour upon annealing at 400 0C for 15 min. The structural and morphological characterizations were carried out using XRD, FE-SEM and HR-TEM that confirm the in-situ growth of Au NPs of 10-100 nm in size. These Au NPs has distinct high purity phase and individual particles embedded into the host matrix. These Au containing Au-TOMs films can be applied for various optoelectronic applications like photo-detectors, sensors, catalysis, solar cells etc.

Authors : Ausrine Jurkeviciute, Mindaugas Juodenas, Vadzim Adashkevich, Tomas Tamulevicius, Jacek Fiutowski, Horst-Gunter Rubahn, Sigitas Tamulevicius
Affiliations : Institute of Materials Science, Kaunas University of Technology, K. Barsausko St. 59, LT-51423 Kaunas, Lithuania; NanoSYD, Mads Clausen Institute, University of Southern Denmark, Alsion 2, DK-6400 Sonderborg, Denmark; Department of Physics, Kaunas University of Technology, Studentų St. 50, LT-51368 Kaunas, Lithuania

Resume : The demand for new functional materials dedicated for sensors and various optical devices is increasing and consequently novel and compatible high throughput micro lithography techniques are emerging. Direct laser interference patterning (DLIP) is an example of fast fabrication method, capable to impose periodic patterns in practically any material upon selection of proper ablation parameters. Ultrashort pulse irradiation can melt and therefore change structure and linear dimensions of nanoparticles. Silver nanoparticles have attracted considerable amount of interest due to their plasmonic properties and wide range of applications. However, silver is a fast oxidising metal and thus requires passivation. One of the possible ways to achieve passivation is embedding silver nanoparticles in passivating matrix, for example diamond-like carbon. In this work, we present Yb:KGW femtosecond laser two second harmonic beams interference ablation of diamond like carbon thin films doped with silver nanoparticles. We investigate the influence on nanoparticle size distributions and one-dimensional periodic structures based on applied number of laser pulses and laser fluence. The DLIP effects are compared for nanocomposites with two different silver contents as well as pure silver and pure diamond-like carbon thin films. It was obtained that existence of silver nanoparticles in thin films lowers the ablation threshold, due to presence of localised surface plasmon absorption.

Authors : Young-Hoi Kim, Chan-Hwa Hong, young-jin kwack, Jun-min Lee, Ho-Yeol Choi, Jae-Min Myoung, and Woo-Seok Cheong
Affiliations : 1) Electronics and Telecommunications Research Institute, Korea 2) Department of Materials Science and Engineering, Yonsei University, Korea

Resume : Low dimensional materials are promising candidate to achieve flexible electronics, because these materials have greater flexibility than do Transparent Conductive Oxide(TCO). however, these materials have mechanical stability issue under high bending stress and repeated deformation. therefore, there are many researchers about low dimensional materials practice to resolve this issue. in this study, through structural engineering we resolved above mentioned issue. we fabricated the Self embedded hybrid electrode using by Copper Mesh on OMO(Oxide/metal/Oxide) and Polymer. with the self embedded structure, we found that our electrodes were sufficiently flexible to withstand a 2mm bending radius(rb) and maintained electrical property under cyclic bending for 2000 iterations. as a result, the self embedded hybrid electrode not only shows outstanding optical(>80%) and electrical property(<0.5Ω/□) but also has a mechanical stability.

Authors : Woo Tae Hong, Jong Won Chung, Jin Young Park and Hyun Kyoung Yang
Affiliations : Department of LED Convergence Engineering, Pukyong National University, Busan 48547, Republic of Korea; Department of LED Convergence Engineering, Pukyong National University, Busan 48547, Republic of Korea; Department of LED Convergence Engineering, Pukyong National University, Busan 48547, Republic of Korea; Department of LED Convergence Engineering, Pukyong National University, Busan 48547, Republic of Korea

Resume : Inorganic phosphors are solid inorganic luminescent materials consisting host lattice, usually doped rare earth impurities. Nowadays, inorganic phosphors were widely used in LED, scintillation and bio-imaging, due to its excellent efficiency and stability. Nevertheless, because these rare earth ions are deposited rarely and extracted with radioactive ions, using a rare earth ions occur high prices, harmful wastes. In order to substitute inorganic phosphors, using a self-activative phosphors, organic materials, quantum dots are suggested. Nevertheless, these materials is not suitable in LED applications, due to the use of heavy metal, low stability and efficiency. Recently, graphene quantum dots have been paid attention due to the low cost and toxicity, high stability, abundant quantity. Owing to its composition, graphene quantum dots were derived from many organic materials. Among organic materials, wasted coffee powder is most typical food waste and its waste rate is high. In this study, the graphene quantum dots derived from wasted coffee powder were synthesized by hydrothermal method. Structural and luminescent properties of the graphene quantum dots were studied. Also, luminescent film were fabricated by combining a graphene quantum dots and polyvinyl alcohol. Acknowledge This research was conducted under the Pukyong National University Research Park(PKURP) for Industry-Academic Convergence R&D support program, which is funded by the Busan Metropolitan City, Korea

Authors : P. Hönicke, B. Beckhoff, I. Holfelder, Y. Kayser, J. Lubeck, B. Pollakowski-Herrmann, C. Seim, C. Streeck, R. Unterumsberger, M. L. Wansleben, J.Weser, C. Zech
Affiliations : Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany

Resume : X-ray spectrometry based on radiometrically calibrated instrumentation, which ensures the physical traceability of quantification to the SI units, is a unique feature of PTB. For X-ray spectrometry, various beamlines are available at PTB’s laboratory at BESSY II in the spectral ranges of soft and hard X-rays (78 eV to 10.5 keV), as well as the “BAMline” for photon energies up to 60 keV. With X-ray spectrometry, surfaces, solids, liquids, nanolayers and nanostructures can be characterized with respect to their physical and chemical properties – such as chemical composition, elemental depth profiles, layer thicknesses, and species and coordination fractions. The functionality of nano-scaled materials with designed physical and chemical properties can provide new functionalities for applications in areas such as health, energy, transport, and climate protection. Such materials have to be developed increasingly fast, which requires reliable analytical characterization methods for a timely correlation of the functionalities with the underlying material properties. However, only few reference materials are available in the different nanotechnology related categories whereas several dozens of new materials are being created every month. This is becoming increasingly problematic as a reliable chemical traceability of numerous characterization technologies can thus not be guranteed. This circumstance – which limits materials research and development – can be counteracted by reference measurement procedures such as, for example, X-ray spectrometry.

Authors : Taeyoung Song, Chulhee Lee, Duk Young Jeon.
Affiliations : Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Republic of Korea

Resume : In display research area, quantum dots(QDs) are receiving attention as next generation emitting materials having narrow full width half maximum and high photoluminescence(PL) efficiency. It consists of core, shell and ligand structure and for high PL efficiency, shell and ligand must be optimized. Their rolls are removal of surface defect and passivation of core emitting light. However, for electroluminescence efficiency, surface consisting of shell and ligand require chemical treatment, generally. For example, for suppressing Förster resonance energy transfer(FRET) or blinking effect, QLED adopted thicker shell QDs and for charge balance, ligand exchange process was used. However, surface treatment causes some problems, PL peak shift, reduced PL efficiency, stability et al. To solve this issue, mixture layer consisting of QD and inorganic nanoparticle(NP) is adapted. NP was synthtsized by heating-up method and its size was 8nm similar to QD size. In QD film, distance of inter-QDs could be controlled by ratio of NP and suppress FRET without QD’s surface treatment. PL quantum yields of QD film became increasing as ratio of NP. In addition, reduced PL decay time recovered. Finally, QLED efficiency improved at appropriate ratio. We have high QLED efficiency by using simple method without complicated surface treatment of QDs.

Authors : Ji Hoon Shon, Hyunjeong Kim, Jae Ick Song, Soo Jin Kim, Gyu Tae Kim
Affiliations : School of Electrical Engineering, Korea University, Seoul 02481, South Korea

Resume : As the design rule for semiconductor devices has significantly shrunk, the need for a new study on novel structures for transistors and materials is drawing much attention in the field. Among the novel materials being studied, two-dimensional transition metal dichalcogenides (TMDs) are widely considered as the next generation materials for semiconducting devices. Here our emphasis is on Rhenium Disulfide (ReS2) whose layers are known to operate independently due to decoupling effect between them. In this study, we suggest an advanced mechanism by demonstrating the electrical characteristics such as mobility and on/off ratio according to the thickness of ReS2 flake and statistically analyzing the experimental data. Moreover, the chemical doping effect of triethanolamine on ReS2 channel can be achieved through experimental results with a variation of flake thickness.

Authors : Seung-Jin Choo, Byung-Chul Lee, Gyu-Tae Kim
Affiliations : School of Electrical Engineering, Korea University, Seoul 02481, South Korea

Resume : Transistors based on two-dimensional (2D) material channel are one of promising candidates for alternative future transistor. However, the operation mechanism of 2D material FETs is not clearly understood yet. Especially Rhenium disulfide (ReS2) is attracting attentions due to the direct bandgap regardless of the thickness and anisotropic electrical characteristic from its unique crystal lattice structure. In our report, to analyze the electrical characteristics of 2D material FETs, we evaluate low frequency noise and reliability by using ReS2 channel FETs. In order to verify 1/f noise and positive bias temperature instability (PBTI), Back gate devices with mechanically exfoliated ReS2 were fabricated. In this study, 1/f noise was measured and data was extracted at 10Hz and 100Hz. Our results show 1/f noise of ReS2FET fitted to CNF (carrier number fluctuation) model. Furthermore to research reliability of ReS2FET, we investigated the PBTI,an important item of reliability. Both of stress and recovery phase were measured in vacuum at various temperatures. It show electrical change with shift in the threshold voltage. 1/f noise and Reliability results in ReS2FET will be presented.

Authors : P. Makushko, M.N. Shamis, M.Yu. Verbytska, T.I. Verbytska, S.I. Sidorenko, Iu.N. Makogon
Affiliations : National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, 03056, Prospect Peremogy 37, Kyiv, Ukraine,

Resume : The effect of annealing atmosphere (vacuum, N2) and the intermediate Au layer on L10 phase formation and magnetic properties in the Fe50Pt50(15 nm)/Au(x nm)/Fe50Pt50(15 nm) films (where х = 0; 7.5; 15; 20; 30 nm) deposited by magnetron sputtering onto SiO2(100 nm)/Si(001) substrates. Heat treatment of the samples was carried out in a vacuum and N2 ambient in the temperature range of 500ºС - 900ºС for 30 s. The phase composition and structure of the as-deposited and annealed films were characterized by X-ray diffraction. The magnetic properties were determined by SQUID – magnetometry. The disordered A1-FePt phase is formed in as-deposited films. Au interlayer thickness effects on initial stress/strain state in FePt layer and thus on temperature of А1 L10 phase transformation at annealing in vacuum. The formation of L10 phase in film with Au(7.5 nm) occurs at 650°С. The increase of Au thickness up to 15 nm lead to change stress sign from compressive to tensile that is accompanied by rise of ordering temperature to 700°С. High initial compressive stress (~10 GPa) in film with Au(30 nm) interlayer promotes reduction of ordering temperature up tо 600°С. Phase transition of A1 L10-FePt starts after annealing in N2 at 500°C independently from intermediate Au layer thickness due to higher heating rate. It is found that increase of Au interlayer thickness inhibits the grain growth of L10-FePt phase in the [001] direction. The coercivity of films with intermediate Au(30 nm) layer after annealing at 900°С is increased up to 27.3 kOe independently from annealing atmosphere. The Au diffuses along grain boundaries and the exchanging coupling interaction between FePt grains is decreased that leads to increase of coercivity.

Authors : Hye-Won Yun1,2, Dong-kyu Kim1, Soo-Jung Kim1, Soong Ju Oh1,*, Sung-Hoon Hong2,*
Affiliations : 1Department of Materials Science and Engineering, Korea University, Republic of Korea 2ICT materials research group, ETRI, Republic of Korea

Resume : Recently, flexible devices have been intensively investigated for future electronic device applications. Among them, the flexible resistive random access memory(ReRAM) device has been considered as a promising candidate for the memory component of flexible electronics because of its low power consumption, fast switching speed and simple structure. Generally, most of the metal oxide layers are prepared with high temperature process because it is necessary to enhance crystallinity and conductivity by thermal treatment. However, almost flexible substrates limit the available temperature range, so they cannot withstand high temperature without decomposing. In this study, we developed a low-temperature process for chemically sintered NiO NCs film with ligand exchange methods. The native ligands on NiO NCs surfaces were peeled off and exchanged with shorter ligand by chemical process. By chemically designing the NCs surfaces, the annealing temperature could be lowered from 300°C to under 200°C because of decreasing the inter-particle distance. As a result, NiO NCs based ReRAM showed excellent characteristics with a high ratio (≥1000) of the high resistance state to the low resistance state. The operational voltage was < 2V, and the reset operational voltage was less than 1V. Moreover, NiO NCs based flexible ReRAM exhibited good memory performance including stable resistive switching characteristic and stable pulse endurance over 100 cycles.

Authors : Emmanuel Nyankson*#, Vasant R. Kumar*
Affiliations : *Department of Materials Science and Metallurgy, University of Cambridge, UK # Department of Materials Science and Engineering, University of Ghana, Ghana

Resume : Pharmaceuticals are emerging contaminants of concern as their incomplete removal during waste water treatment has resulted in their detection in surface and groundwater. To address this problem, a highly efficient visible light active Ag3PO4-halloysite nanoclay photocatalyst which also acts as an excellent adsorbent was synthesized and its application in the removal of ibuprofen, naproxen sodium, diclofenac sodium and flurbiprofen examined. The synthesized Ag3PO4-HNT was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS). Ag3PO4-HNT was more effective in photodegrading ionic pharmaceuticals than neutral pharmaceuticals. It was observed that the aqueous dispersity of Ag3PO4 was enhanced upon the addition of the HNT and as a result improved the photocatalytic efficiency. The adsorption ability of Ag3PO4 was also enhanced upon the addition of HNT. The adsorption efficiency of Ag3PO4-HNT was high with ionic pharmaceuticals than neutral pharmaceuticals. The observed adsorption behavior of Ag3PO4-HNT can be ascribed to the surface charge characteristics of HNT. The photodegradation by-products of ibuprofen and naproxen sodium were identified with LC-MS and possible degradation pathways proposed. The synthesized Ag3PO4-HNT could have wide ranging applications in water purification systems.

Authors : Victor Soltwisch, Anna Andrle, Philipp Hönicke, Yves Kayser, Jürgen Probst, Burkhard Beckhoff, Frank Scholze
Affiliations : Physikalisch-Technische Bundesanstalt, Helmholtz-Zentrum Berlin

Resume : To improve metrology applications we evaluate the potential of grazing incidence X-ray fluorescence (GIXRF) and grazing incidence small angle X-ray scattering (GISAXS) techniques for the characterization of nanostructured surfaces. Even with rather short X-ray wavelengths it is possible to use a rigorous Maxwell solver based on finite-elements for the simulation of the near field and far field intensity distribution. The simulated far field intensity can describe the measured GISAXS diffraction pattern and allows the reconstruction of the line profile. The electric field intensity inside the structure material is directly proportional to the fluorescence emission measured. The spatial resolution coupled with the material selectivity potential of the fluorescence emission spectroscopy gives rise to an enhanced sensitivity in X-ray scattering experiments.

Authors : Iuliana Caraman1, Veaceslav Sprincean2, Dumitru Untila1,2, Ala Cojocaru3,4, Oleg Lupan4,5, Silvia Evtodiev1, Mihail Caraman1
Affiliations : 1Ghitu Institute of Electronic Engineering and Nanotechnologies, Academy of Sciences of Moldova, Academiei, 3/3, MD-2028, Chisinau, Republic of Moldova; 2Faculty of Physics and Engineering, Moldova State University, Alexei Mateevici, 60, MD-2009, Chisinau, Republic of Moldova; 3PhI-Stone AG, Kaiserstasse 2, D-24143, Kiel, Germania; 4Funtional Nanomaterials, Institute for Materials Science, Kiel University, Kaiser Str. 2, D-24143, Kiel, Germania; 5Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, Stefan cel Mare Avenue, 168, MD-2004, Chisinau, Republic of Moldova

Resume : By thermal annealing of the Ga2S3 crystals in normal or oxygen enriched atmosphere, at temperatures close to the melting point, the sulphur atoms from the Ga2S3 semiconductor are replaced by oxygen atoms. In this work crystalline structure, surface morphology and photoluminescence of the Ga2S3 – Ga2O3 composite, are studied by XRD, EDX, SEM, Raman and PL methods. The Ga2S3 – Ga2O3 composite was obtained by thermal annealing of Ga2S3 crystals, in normal atmosphere at 1100K, for 1 hour up to 24 hours. It was established by SEM, XRD and Raman methods, that as an annealing result, the surface of Ga2S3 single crystals is covered by a layer of β-Ga2O3 nanowires. The nanowires are concentrated as islands onto surface, in the case of thermal annealing lasting 1-6 hours, and cover the surface as a homogenous layer in the case of 12-24 hours annealing. The length of Ga2O3 nanowires depends on the thermal annealing duration and reaches ~3 μm for the samples annealed for 24 hours. The obtained composite (Ga2S3 – Ga2O3) is a material photoluminescent in the violet and red-orange spectral regions.

Authors : Woosuk Choi, Minwook Kim, Yongho Seo*
Affiliations : Department of Nanotechnology and Advanced Material Engineering, and Graphene Research Institute, Sejong University, Seoul, 143-747, Korea Department of Nanotechnology and Advanced Material Engineering, and Graphene Research Institute, Sejong University, Seoul, 143-747, Korea Department of Nanotechnology and Advanced Material Engineering, and Graphene Research Institute, Sejong University, Seoul, 143-747, Korea

Resume : 2D materials family, such as hexagonal boron nitride (h-BN), silicene and hexagonal transition metal dichalcogenide (TMDC) as an insulating and semiconducting materials, are actively investigated, started from graphene. In particular, it is noted that TMDC with direct bandgap, such as MoS2, MoSe2, WS2, and WSe2, show strong light–matter interactions in the visible range. To utilize these characteristics, many researchers have studied heterostructures, and many papers have been published. However, most of the papers have dealt with heterostructure composed of monolayer TMDCs, while the opto-electric properties of heterostructure composed of few layer TMDCs are not yet known well. To compare the characteristics of the heterostructure of the monolayer TMDC with few-layer heterostructure, we fabricated nano-devices using a few-layer exfoliated WSe2 and MoSe2, and its optoelectronics were investigated with I-V curve measurement and gate field effect under LED light (365 nm, 530 nm, and 850 nm) illuminations. On the other hand, it has been reported that 2D vertical stacks of dissimilar hexagonal monolayers exhibit unusual electronic, photonic and photovoltaic responses arising from interlayer excitations depending on crystal orientation.1, 2 To confirm this phenomenon in few-layer heterostructure, we fabricated samples by stacking WSe2 and MoSe2 with different crystalline angles by means of pick-up transfer method. Various measurements such as HR-XRD, TEM, AFM, Raman spectroscopy, and photoluminescence were used to characterize its properties such as crystal orientation, thickness, and optical properties. As a result, the heterostructure with 15 twist angle showed a remarkably high photocurrent generation at the short wavelength illumination (365 nm) Reference 1. H. Heo, J. H. Sung, S. Cha, B. G. Jang, J. Y. Kim, G. Jin, D. Lee, J. H. Ahn, M. J. Lee, J. H. Shim, H. Choi and M. H. Jo, Nat Commun, 2015, 6. 2. P. K. Nayak, Y. Horbatenko, S. Ahn, G. Kim, J. U. Lee, K. Y. Ma, A. R. Jang, H. Lim, D. Kim, S. Ryu, H. Cheong, N. Park and H. S. Shin, Acs Nano, 2017, 11, 9566-9566.

Authors : Sangkoo Kang, Youngjun Kim, Kyung Yong Ko, Jusang Park, and Hyungjun Kim
Affiliations : School of Electrical and Electronic Engineering, Yonsei University

Resume : Transition metal dichalcogenides (TMDCs) are introduced as layered materials which have attracted great attention as gas sensing materials with high sensitivity, due to their large surface-to-volume ratios and semiconducting properties. Unlike metal oxide sensors, the TMDCs based sensor shows tremendous sensitivity at room temperature that overcomes the limitation of metal oxide gas sensor. Therefore, synthesis of atomically thin MoS2 with layer controllability and wafer-scale uniformity is essential for their applications in gas sensor. However, despite of the fact that the electrode material selection is the important factor in other electronic applications such as transistor and photo detector. The effect of electrodes such as work function, contact resistance in TMDCs based gas sensor is rarely studied. In this work, we focused on the gas sensor characteristics of TMDCs (MoS2, WS2) according to various electrodes. MoS2 and WS2 are achieved on SiO2 by CVD process with Mo(CO)6 and W(CO)6 as precursor and H2S as reactant at low temperature (~300 ℃). The synthesized TMDCs are evaluated using spectroscopy (Raman, XPS) and microscopic analysis (SEM). We demonstrate the realization of TMDCs based gas sensor with various electrodes (Ti/Au, Al, Pd, Ag, etc) and evaluating its electrode dependence characteristics such as current level, electrical property, response rate etc. This study gives fundamental direction of proper electrode selection for TMDCs gas sensing devices (NO2, NH3, CO, CO2, etc).

Authors : Viktar Khaliava, Arseni Klimenka
Affiliations : Micro- and Nanoelectronics Department, BSUIR, P. Browka 6, 220013 Minsk, Belarus; Micro- and Nanoelectronics Department, BSUIR, P. Browka 6, 220013 Minsk, Belarus.

Resume : Fabrication of plasmonic arrays of silver-coated silicon nanowires (SiNWs) demonstrating activity in the surface enhanced Raman scattering (SERS) is reported. SiNWs were grown in lightly doped n-Si by metal-assisted chemical etching. In accordance with this method, silver nanoparticles were deposited on the Si surface from a aqueous solution of AgNO3, followed by etching in a solution of HF and H2O2. The resulting SiNWs were coated with SERS-active silver nanostructures by immersion into an aqueous solution of AgNO3. As known, the strongest Raman enhancement is observed if an excitation wavelength coincides with the surface plasmon resonance (SPR) of the metallic nanostructures. The SPR can be found via reflectance spectrum of the metallic nanostructures. Here we simulated reflectance spectra of the Ag/SiNWs samples using CST Student Edition and then compared them with the experimental results obtained by the measurements in the range from 200 to 1000 nm using the spectrophotometer Proscan MC 122. It was found that the SPR band of the Ag/SiNWs samples belongs to the blue region and is the most intensive at 470 nm. SERS-activity of the Ag/SiNWs samples was checked with rhodamine 6G. The water solution of 10-6-10-10 M rhodamine 6G was drop-deposited on the silver surface and air-dried. SERS-spectra were recorded with 3D scaning confocal Raman microscope Confotec NR500 using 473 nm laser to match with the resonance condition. The detection limit of rhodamine 6G reached 10-9 M.

Authors : Wipakorn Jevasuwan, Junyi Chen, Thiyagu Subramani, Ken C. Pradel, Toshiaki Takei, Kotaro Dai, Kei Shinotsuka, Yoshihisa Hatta, Ryo Matsumura, and Naoki Fukata
Affiliations : International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan

Resume : Nanowire (NW) structures possess several benefits for the photovoltaic application compared to planar substrates owing to their physical properties. However, it still necessitates to provide adequate NW structure with excellent surface quality, low light reflection, controllable density and positioning to enhance the solar cell performances. In this work, two different SiNW structures synthesized by large-area and inexpensive methods between metal-catalyzed electroless etching (MCEE) and colloidal lithography followed by inductively coupled plasma reactive ion etching were studied for photovoltaic application. The higher density and smaller diameter SiNWs with random position could be provided by MCEE. Array of pencil-shaped SiNWs with 500-nm pitch were formed by colloidal lithography. The very low light reflectance of MCEE- and pencil-shaped SiNW arrays were observed at <10% and <5%, respectively. Good alignment and sufficient spacing of pencil-shaped SiNWs could gain the better light absorbance and reduce the reflectance at the top of NW structure. The solar cells were fabricated by depositing p -Si shell layer onto the n-SiNW structures. The H2 annealing was applied into the processes for improving the NW surfaces, the crystallinity of shell layer. The annealing parameters of temperature, time, and sequence were optimized. The highest efficiency of pencil-shaped SiNW solar cells (8.5%) were higher than that of MCEE-SiNW solar cells (7.9%). The better controls of the SiNW shape, density and pattern by colloidal lithography accompanied with appropriated H2 treatments produced lower light reflectance SiNW structure and better solar cell junction than MCEE technique. [W. Jevasuwan, et al., JJAP, 56 (2017) 085201]

Authors : Minwook Kim, Woosuk Choi, Yongho Seo*
Affiliations : Department of Nanotechnology and Advanced Material Engineering, and Graphene Research Institute, Sejong University, Seoul 05006, Republic of Korea; Department of Nanotechnology and Advanced Material Engineering, and Graphene Research Institute, Sejong University, Seoul 05006, Republic of Korea; Department of Nanotechnology and Advanced Material Engineering, and Graphene Research Institute, Sejong University, Seoul 05006, Republic of Korea;

Resume : Dimensionality has been considered as an important factor which decides the characteristics of materials. Recently, two-dimensional (2D) materials, such as graphene, transition metal dichalcogenides (TMDC), boron nitride (BN), are considered emerging materials which show extraordinary characteristics compared with bulk materials. Exfoliating thin flakes from a bulk van der Waals material is an important step to investigate physical, electrical, and optical characteristics of 2D materials. Some methods to fabricate 2D materials have been developed such as chemical vapor deposition (CVD) method, solvent exfoliation method, and micromechanical method. Among them, micromechanical method has been utilized to obtain high quality samples due to its simplicity of the process. However, the conventional micromechanical method has some disadvantages: small size, low yield, and low visibility. In order to overcome these problems, there have been many attempts to increase the area and a probability to find the single layer flakes, based on the conventional micromechanical method. It has been reported that the removal of trapped gas molecules between 2D materials and the substrate is processed by annealing, which increases the van der Waals interaction at the interface. Many large single layer flakes were reportedly obtained by heating the sample with the Scotch tape at 100 Celcius degrees.1 From those results, the pressure difference was considered as a main effect to evacuate the gas to obtain the single layer flakes. To make higher pressure difference, the sample was placed in a vacuum chamber in our experiments, causing 1 atm pressure difference between the inside and outside of the 2D material. The samples by vacuum method were compared with those by annealing method using optical microscopic measurement and Raman spectroscopy. The probability to obtain single layer flakes was in the similar level, but the size of the flakes by annealing was larger than those by vacuum method. This result can be explained by the adhesive process for the samples in high temperature with assistance of impurities. Reference 1. Yuan Huang; Eli Sutter; Norman N. Shi; Tianzhong Yang; Dirk Englund; Hong-Jun Gao; Peter Sutter. Reliable Exfoliation of Large-Area High-Quality Flakes of Graphene and Other Two-Dimensional Materials. ACS Nano 2015, 9, 10615-10620

Authors : Filipp S. Talalaev (a), Sergey Yu. Luchkin (b), Ernst Z. Kurmaev (c, d), Pavel A. Troshin (b, a)
Affiliations : (a) Institute for Problems of Chemical Physics of Russian Academy of Sciences, Semenov Prospect 1, Chernogolovka, Moscow region 142432, Russia; (b) Center for Electrochemical Energy Storage, Skolkovo Institute of Science and Technology, Nobel St. 3, Moscow 143026, Russia; (c) Institute of Physics and Technology, Ural Federal University, Mira 19 Street, Yekaterinburg 620002, Russia; (d) M. N. Mikheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, S. Kovalevskoi 18 Street, Yekaterinburg 620990, Russia

Resume : Rare earth metal oxides (REOs) are considered as promising replacements for silicon dioxide dielectric in the integrated circuit technology due to their advanced dielectric properties potentially enabling further downscaling of electronics. Indeed, using Sm2O3 instead of SiO2 allows one to reduce the thickness of the dielectric and suppress significantly leakage currents. The application of solution processed REOs nanoparticles for fabrication of organic field-effect transistors (OFETs) has been demonstrated recently, though this approach might face reproducibility and reliability issues in real world applications (ACS Appl. Mater. Interfaces, 2016, 8, 31128). Here we propose a straightforward approach for growing high-quality REO dielectric films by controlled oxidation of the metal coatings in air at elevated temperatures. This process is facile and quick, since optimal annealing time is within few minutes, and delivers highly reproducible results. The performance of the produced REO coatings as gate dielectrics in OFETs was investigated using a panel of organic semiconductors: fullerene C60, pentacene, DNTT, C12-PDI and etc. The devices comprising REO dielectric showed higher charge carriers mobilities and lower operation voltages in comparison with the reference samples produced using electrochemically grown AlOx. The obtained results prove that emerging REO dielectrics might impact positively the development of organic electronics at both laboratory and industrial scales.

Authors : S.P. Rodichkina (a,b), A.V. Pavlikov (a), T. Nychyporuk (b), V. Lysenko (b,c), V.Yu.Timoshenko (a,c,d)
Affiliations : (a) Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia; (b) University of Lyon, INSA de Lyon, INL, UMR CNRS 5270, Lyon, France; (c) National Research Nuclear University MEPhI, Kashirskoye Sh. 31, 115409 Moscow, Russia; (d) Lebedev Physical Institute of RAS, Leninskiy Prospekt 53 Leninskiy Prospekt,119991 Moscow, Russia

Resume : Doped silicon nanowires (SiNWs) represent a promising material for optoelectronics, thermoelectricity, chemical and biological sensors. Research and application of SiNWs require fast and convenient methods to determine the carrier concentration in Si nanostructures. In this work we propose to determine the free charge carriers concentration in p-type SiNWs by using the Raman spectroscopy. In contrast to the electrical methods, the Raman spectroscopy is contactless and can be applied to nanostructures of different morphologies. Applying this method, we have determined the free hole concentration in SiNWs fabricated by metal-assisted chemical etching of c-Si wafers followed by additional p-type (Boron) doping via thermal stimulated diffusion. The free hole concentrations in doped SiNWs were shown to be of the order of 1019…1020 cm-3 for different preparation conditions. The obtained results are interesting for potential application of the proposed doping method to fabricate highly doped SiNWs for photonic and thermoelectrical devices.

Authors : Rosana Alves Gonçalves, Mauricio Ribeiro Baldan, Adenilson José Chiquito, Olivia Maria Berengue.
Affiliations : São Paulo State University; National Institute for Space Research; Federal University of São Carlos; São Paulo State University

Resume : The development of nanotechnology and the urge of scale reduction of semiconductor materials have been creating new perspectives on the development of optoelectronic devices in which a nanostructure plays a fundamental role. Since carbon nanotubes were discovered by Iijima in 1991 great importance is given to de growth of nanostructures (nanowires, nanobelts, nanoparticles, quantum dots) and different approaches are commonly used to this purpose such as vapor-solid-liquid process (VLS), vapor-solid process (VS), Vapor-Solid-Solid process (VSS) and so forth. Within the nanostructured materials group we can quote Transparent Conductive Oxides (TCO) as an important class materials which can be synthesized in nanostructured form and have interesting electronic and optical properties which makes them interesting for applications in gas sensors, chemical sensors and field effect transistors. Antimony trioxide is a transparent conductive oxide that is commonly used as flame retardant but was recently synthesized in nanostructured form and presents important properties such as wide band gap (3.3 eV), great optical transparency and chemical activity as catalytic agent. Aiming to add data on electrical and optical properties of nanostructured Sb2O3, in this work, it was synthesized branched microbelts and nanobelts of antimony oxide through vapor-solid (VS) growth method associated with a carbothermical reduction process. The synthesized samples were characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman Spectroscopy and new data on the growth method, crystalline structure and quality, morphology and possible preferential growth regions on the synthetized samples were found. Samples were found to be orthorrombic with a possible preferential growth direction in [222] (Punctual group Fd-3m, PDF 01-072-1334). The examination of Raman selection rules in both orthorhombic and cubic samples revealed solid evidence on the presence of native defects, which we believe to be oxygen vacancies. Symmetric Schottky barriers were constructed to orthorhombic Sb2O3 samples and the main features of the devices such as barriers height ΦB = 0.44 eV and ideality factor n = 1.03 for Au/Ti contacts were found. The temperature-dependent resistance measurements show the expected behavior for semiconductor materials.

Authors : A.B. Bogoslovska, D.O. Grynko
Affiliations : Institute of Semiconductor Physics of NAS of Ukraine, pr.Nauki 41, Kyiv 03028, Ukraine

Resume : Nanostructured materials have drawn great scientific and technical interest, due to their unique properties and possibilities of utilization in novel promising optoelectronic and sensoric devices, solar cell, display panel and so on. One-dimensional cadmium sulfide nanowhiskers are bright example of such objects. Nanocrystals of CdS have peculiar properties, which distinguish them from bulk material. Structure, morphology, sizes of nanocrystals, which defines the ratio of surface and bulk region, define physical properties of such a crystals. This work is devoted to investigations of luminescent properties of CdS nanowhiskers grown from gas phase with different technological parameters what allows to control sizes and morphology of obtained nanocrystals. The influence of these parameters on physical and optical properties of CdS nanowhiskers is analyzed. CdS whiskers were grown from gas phase in home-made equipment. Growth was realized as on clean substrates as on substrates covered by small mass thickness layer of Au or Ag. Micro-droplets of those metals serve as nuclei for CdS condensation accelerating the growth speed in orders of magnitude from one side and provide some doping of grown whiskers from other side what was revealed by luminescent investigations. Correlation of luminescent properties with the growth parameters is demonstrated.

Authors : T.O. Mishakova, E.G. Bortchagovsky
Affiliations : Institute of High Technologies, Kyiv National University, Glushkov ave. 4g, Kyiv 03022, Ukraine; Institute of Semiconductor Physics of NAS of Ukraine, pr.Nauki 41, Kyiv 03028, Ukraine

Resume : Understanding of the background of the field distribution is vital for tip-enhanced Raman scattering. However even the behavior of the ratio of fields at the tip apex and at the approaching surface is important for the implementation of Raman probe [1] and its use as the internal standard in tip-enhanced Raman scattering [2]. Modeling of the fields ratio was made by two approaches: simple sabstitution of the system by few interacting dipoles [3]; and on the base of boundary elements method with the toolbox MNPBEM [4]. Obtained by simple dipolar modeling qualitative conclusion about influence of surface plasmon resulting in nonmonotonous behaviour of the fields ration versus tip proximity was confirmed by exact calculation by boundary elements method. It was also shown that roughnesses remarkably enhance the field at the substrate in comparison to the flat surface. [1] E.G. Bortchagovsky, U.C. Fischer, Nanoscale vol.4, pp.885-889 (2012). [2] E.G. Bortchagovsky, T. Schmid, R. Zenobi, Appl. Phys. Lett. vol.103, 043111 (2013). [3] E. Bortchagovsky, Nanospectrosc. vol.2, pp.7-14 (2016). [4] U. Hohenester, A. Trügler, Comput. Phys. Commun. vol.183, pp.370-381 (2012).

Authors : H. Klym (1), A. Ingram (2), O. Shpotyuk (3,4), L. Calvez (5)
Affiliations : (1) Lviv Polytechnic National University, 12 Bandera Str., Lviv, 79013 Ukraine (2) Opole University of Technology, 75 Ozimska Str., Opole, 45370 Poland (3) Vlokh Institute of Physical Optics, 23 Dragoanova Str., Lviv, 79005 Ukraine (4) Institute of Physics of Jan Dlugosz University, 13/15 al. Armii Krajowej, Czestochowa, 42201 Poland (5) Equipe Verres et et Céramiques, UMR-CNRS 6226, Institute des Sciences chimiques de Rennes, Université de Rennes 1, Rennes Cedex, France

Resume : Ge-Ga-Se chalcogenide glasses are known as suitable materials for potential applications in optical modulators or frequency converters, as efficient laser host media and in fiber-optical amplifiers working in the IR spectral region. In the present research, we apply the x-ray diffraction (XRD), positron annihilation lifetime (PAL) spectroscopy complemented with doppler broadening of annihilation radiation (DBAR), atomic force microscopy (AFM) and scanning electron microscopy (SEM) methods in order to perform structural characterization of 80GeSe2-20Ga2Se3 chalcogenide glasses thermally-activated at 380 oC for 25, 50 and 80 h. It is shown that structural changes caused by crystallization can be adequately described by positron trapping modes. The observed changes in defect-related component in the approximation of experimental positron lifetime spectra for annealed glasses speaks in favour of structural fragmentation of larger free volume entities into smaller ones. The results of combined PAL-DBAL measurements below confirm such diversity of void evolution processes in the studied glasses. As it was shown from XRD results, with increasing annealing time from 25 h and further to 50 and 80 h, the well-pronounced crystalline peaks at 2 ~ 28° are observed. Peaks positions are in good agreement with GeGa4Se8 phase indexation. The size of nanocrystalline inclusions is near 9–10 nm. Crystallization of GeSe2 phases in form of wires with length near 1-3 m is a surface phenomenon.

Authors : Jae Bon Koo, Chan Woo Park, Hojun Ryu and Chi-Sun Hwang
Affiliations : Electronics and Telecommunications Research Institute (ETRI) ICT Materials and Components Research Laboratory Reality Display Research Division

Resume : Stretchable electronics has been considered as a promising technology for overcoming the limitations of conventional rigid electronic systems, in various applications such as foldable or stretchable displays, wearable bio-devices, as well as sensor skins for robots. The largest market for stretchable electronics is expected in the field of display application. Especially, stretchable displays can be embedded in or attached on automobile windows. Micro LED (Light Emitting Diode) is recently considered as stretchable light-emitting device due to high reliability, high flexibility and high brightness. Transparency and stretchability in x and y direction with dual radius curvature are required for stretchable automobile display. We have reported some flexible and stretchable thin-film transistors (TFTs) using elastomeric substrates such as polydimethylsiloxane (PDMS). However, TFTs can withstand an applied strain of up to 2% without electrical degradation and mechanical fractures even though the substrate is stretched up to several tens of % strain. To solve the above problems, both total transfer onto pre-stretching substrate method and rigid island on perforated substrate method were proposed to fabricate for stretchable TFT array. Furthermore, indium-gallium-zinc oxide (IGZO) was chosen as the active channel layer. The employment of an oxide semiconductor as the active channel layer for TFTs can be a good approach for realizing excellent transistor performance including high mobility and relatively low voltage operation. The oxide TFTs are also suitable for automibile display with high resolution and high transparency.

Authors : J.-C. Grivel
Affiliations : Technical University of Denmark

Resume : ZnO films prepared on glass plates using water based coating solutions were tested for industrial dye photocatalytic decomposition in various types of waters (demineralised water, sea- and lake-water). The influence of various parameters such as wavelength and attenuation of incident radiation by dye absorption was studied. The efficiency of the ZnO films towards water purification is compared with that of ZnO particles as well as those of natural sediments present to the water sources under study. The influence of biological activity in natural waters will be discussed.

Authors : Yuta Tonooka, Masashi Ota, Yudai Kikuchi, Tomohiro Hirano, Mitsuo Fukuda
Affiliations : Department of Electrical and Electronic Information

Resume : Three plasmonic wirings were numerically and experimentally examined for applying to plasmonic integrated circuits in 1300- and 1550-nm-wavelength bands and compared with electric wiring to clarify the feasibility of plasmonic wiring. The three plasmonic wirings were a SiO2-stripe waveguide on a Au film, a Au-stripe waveguide on a Si substrate, and a Au/SiO2-stripe waveguide on a Si substrate. The configuration of electric wiring is universal type (Cu stripes surrounded with SiO2) which are generally used in silicon ICs. All the cross-sectional area were set at 500 nm (width) x 500 nm (hight) to compare the characteristics under the same conditions. The transmission speeds of plasmonic signals were numerically estimated to be about 2.0×108 m/s for the three types of plasmonic wiring and about two orders of higher than that of electric signals. The signal transmission loss of each wiring was numerically and experimentally examined, and we clarified that plasmonic wirings are superior to electric ones if the distance of signal transmission is less than a few hundreds of micrometers. Here, a SiO2-stripe waveguide on a Au film showed the best performance. For the metal film of a SiO2-stripe waveguide, Cu, Al and Ag were examined instead of Au, and the performance of an Al film was confirmed to be comparable to that of a Au film. Based on these numerical and experimental results, we have clarified a suitable plasmonic wiring structure.

Authors : T. Hirano, M. Ota, Y. Tonooka, Y. Kikuchi, M. Fukuda
Affiliations : Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology

Resume : A novel plasmonic mode converter having a compact structure is proposed for plasmonic integrated circuits. The mode converter consists of a multimode interferometer (MMI) and is designed by introducing a tapered waveguide structure to a normal rectangular shaped MMI. A mode converter, in which plasmonic multiple (higher) modes were converted to a single (fundamental) mode, was designed by finite-difference time-domain (FDTD) method. The behaviors of the mode-conversion ratio and the phase shift within the tapered waveguide were simulated for various tapered structures, and the mode conversion effects were confirmed. The structure of the converter was very simple and fabricated by patterning a SiO2 film deposited on a Au film using focused ion beam milling technique. For the converters fabricated, the distributions of surface plasmon intensity were monitored with a scanning near-field optical microscope, and the mode conversion was confirmed experimentally. Based on these simulation and experimental results, a suitable structure was clarified for mode conversion. This type of mode converter will be indispensable to develop compact plasmonic integrated circuits.

Authors : Tien-Chai Lin1, Wen-Chang Huang2, 3*, Bai-Jhong Jheng1
Affiliations : 1 Department of Electrical Engineering, Kun Shan University, No. 195, Kun-Da Rd., Yung-Kang Dist., Tainan, 71003, Taiwan, ROC 2 Department of Electro-Optical Engineering, Kun Shan University, No. 195, Kun-Da Rd., Yung-Kang Dist., Tainan, 71003, Taiwan, ROC 3 Green Energy Technology research Center, Kun Shan University, No. 195, Kun-Da Rd., Yung-Kang Dist., Tainan, 71003, Taiwan, ROC

Resume : RF magnetron co-sputtering deposition of nickel-doped vanadium pentoxide on the ITO glass substrate film were investigated. The structural, electrical and optical of the nickel doped vanadium pentoxide film determined by X-ray diffraction, FE-SEM, UV-visible spectrometer, atomic force microscopy and auger electron spectroscopy. The electrochromic properties of the device was evaluated by cyclic voltammetry. For the undoped vanadium pentoxide, the variation of transmittance between colored and bleached states at a wavelength of 600 nm was 25.6%. For the nickel-doped vanadium pentoxide film, slightly change of the film nature was occurred at the low power (<30W) doping sample. As the doping power is above 50W, the amount of nickel in the film increased, it deepens anode color of the vanadium pentoxide thin film. This leads to the film change from cathode coloration to anode coloration. As the doping power was 80W, a best electrochromic properties obtained. The transmittance change between colored and bleached states at a wavelength of 600nm was 35.2%.

Authors : Tien-Chai Lin1, Wen-Chang Huang2, 3*, Jyun-Yan Wu2
Affiliations : 1 Department of Electrical Engineering, Kun Shan University, No. 195, Kun-Da Rd., Yung-Kang Dist., Tainan, 71003, Taiwan, ROC 2 Department of Electro-Optical Engineering, Kun Shan University, No. 195, Kun-Da Rd., Yung-Kang Dist., Tainan, 71003, Taiwan, ROC 3 Green Energy Technology research Center, Kun Shan University, No. 195, Kun-Da Rd., Yung-Kang Dist., Tainan, 71003, Taiwan, ROC

Resume : The ZnO:Mg nano-structural thin film deposited by an RF co-sputtering system for the application of hydrogen sensor is presented. Thickness effects and magnesium doping effects of the structural and gas sensing properties were stressed. It shows that the ZnO (002) preferential growth is more obvious at the thicker film and the grain size is increase with the thickness. The strong ZnO (002) peaks of preferred orientation, indicating that ZnO thin films were in a preferential c-axis orientation due to the lowest surface free energy of the (002) plane. The sensing response increase with the film thickness which is due to the increase of oxygen vacancies and leads to higher defect density. A sensing response of 2.46 for hydrogen concentration of 1000 ppm is obtained at the film with thickness of 432 nm at 300 C environment. For the magnesium doping effects , it is found that the crystalline of the ZnO:Mg film is improved with the increase of Mg concentration, while it becomes worse as the Mg concentration is too high. The roughness of the film surface is increased with the increased doping of Mg element. The sensing response of the film is increased with Mg doping which is due to its roughness of surface morphology.

Authors : Yash Gupta, Mrinal Poddar, Mahima Sharma, Monika Joshi, Subhasha Nigam, D K Avasthi, Yogendra Kumar Mishra, Rainer Adelung.
Affiliations : Amity Institute of Nanotechnology, Amity University, Sector 125 Noida, India; Amity Institute of Biotechnology, Amity University, Sector 125 Noida, India; Functional Nanomaterials, Institute for Materials Science, Kiel University, Kaiserstr. 2, D- 24143, Kiel, Germany.

Resume : Semiconductor nanomaterials have been explored in variety of environmental applications. In this study, an attempt was made to synthesize various nanoparticles and their nanocomposites showing photocatalyst, such as CuO, ZnO and ZnO-T (ZnO-Tetrapods), and their nanocomposites i.e. CuO/ZnO and CuO/ZnO-T(ZnO-Tetrapods) by a facile and economically viable hydrothermal route. The resulting photocatalysts were characterized to determine their properties, such as morphology, band gap, crystalline structure, etc. by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), UV-Visible Absorption Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD). The potential efficacy of above photocatalysts was evaluated towards the photoremediation of Crystal Violet (CV) dye under solar light. The fast photocatalytic degradation of CV dye by pure ZnO-T could be further enhanced by hybridization with CuO due to the suppressed charge-carrier recombination. The results suggested that pure as well as nanocomposites of ZnO may be a promising candidate for waste water treatment.

Authors : Bharat Pant and Ahalapitiya H Jayatissa
Affiliations : Department of Mechanical, Industrial and Manufacturing Engineering (MIME), The University of Toledo, Toledo, OH 43606, USA.

Resume : The gas sensing properties of NiO and NiO: Graphene composite thin films were investigated. NiO and NiO: Graphene samples were fabricated on a glass substrate by a sol-gel method. To get NiO: Graphene composite film, graphene was added to the precursor solution in the concentration of 2%, 4% and 6% by weight and stirred for 1 hour. Then the precursor was coated on the substrate by a spin coating method. The sensor’s electrical, optical, crystallographic properties were studied using different techniques. XRD data show that the films were polycrystalline with (111) and (200) planes, respectively. The average activation energy was found to be 0.32 eV from the Arrhenius plots between conductivity and temperature. The response of the sensors strongly depended on operating temperature and sensors displayed the highest sensitivity at 225°C. The NiO: 4% graphene composite sample displayed the highest sensitivity of 35% and 39% for 75 ppm of NH3 and 3000 ppm of H2 gases, respectively. The sensitivity, response time and recovery time of the composite films were improved compared with pure NiO films. The sensor showed excellent repeatability and low cross-sensitivity for NH3 against CH4 gas. The resistance of pure graphene film was increased when exposed to the NH3 gas, which proved that pure graphene has p-type characteristics similar to NiO. In this paper, details of experimental and theoretical results will be presented.

Authors : Yanxiu Li, * He Huang, Yuan Xiong, Stephen V. Kershaw, Andrey L. Rogach
Affiliations : Department of Materials Science and Engineering, Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong S.A.R.

Resume : Lead halide perovskites, both in the form of thin films and colloidal nanocrystals (NCs), have recently attracted a lot of attention as components of solar cells, light-emitting diodes, and photodetector.[1-3] We developed microwave assisted slowed-down synthesis of CsPbBr3 perovskite nanocrystals, which retards the reaction and allows us to gather useful insights into the formation mechanism of these nanoparticles, by examining the intermediate stages of their growth. The trends in the decays of the emission intensity of CsPbBr3 nanocrystals under light exposure are well correlated with their stability against decomposition in TEM under electron beam. The results point out on the change of the crystal structure of CsPbBr3 nanocrystals from a deficient and easier to be destroyed lattice to a well crystallized one. Conversely the shift in the ease of degradation sheds light on the formation mechanism, indicating first the formation of a bromoplumbate ionic scaffold, with Cs ion infilling lagging a little behind. Increasing the cation to halide ratio towards the stoichiometric level may account for the improved radiative recombination rates observed in the longer reaction time materials. 1. H. Huang eta l., Adv. Sci. 2015, 2, 1500194 2. H. Huang et al., Nat. Commun. 2017, 8, 996. 3. Y. Li et al., Angew Chem Int Ed. 2018, 57, 5833-5837

Authors : Yuan Xionga,* Minshen Zhu,b He Huanga, Stephen V. Kershaw,a Chunyi Zhib, and Andrey L. Rogacha
Affiliations : aDepartment of Materia ls Science and Engineering and Center for Functional Photonics (CFP), City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong S.A.R. bShenzhen Research Institute City University of Hong Kong Shenzhen 518000, China

Resume : A cellulose paper has been impregnated with light-emitting CdTe nanocrystals and carbon dots, and filled with polyurethane to fabricate uniform transparent composite films with bright photoluminescence of red (R), green (G), and blue (B) (RGB) colors. A building brick-like assembly method is introduced to realize RGB multicolor emission patterns from this composite material.1 By sectioning out individual pixels from monochrome emissive composite sheets, the advantage of the self-healing properties of polyurethane is taken to arrange and weld them into a RGB patterned fabric by brief exposure to ethanol. This provides an approach to form single layer RGB light-emitting pixels, such as potentially required in the display applications, without the use of any lithographic or etching processing. The method can utilize a wide range of different solution-based kinds of light-emitting materials. References 1. Xiong, Y., Zhu, M., Wang, Z., Schneider, J., Huang, H., Kershaw, S. V., . . . Rogach, A. L. (2018). A Building Brick Principle to Create Transparent Composite Films with Multicolor Emission and Self‐Healing Function. Small, 14(20), 1800315.

Authors : Sagar Sen1,a, , B.K. Panigrahi2, R.J. Choudhary3 Ajay Gupta4, Ratnesh Gupta1,b
Affiliations : 1 School of Instrumentation, Devi Ahilya University, Khandwa road, Indore-452001, India. 2Material Science Division, Indira Gandhi Center for Atomic Research, Kalpakkam 603 102, India. 3UGC DAE CSR Indore Centre, Indore-452017, India. 4Center for Spintronics, Amity Univ., Noida, India.

Resume : Magnetic materials have been widely used in the areas of magnetic data storage devices, magnetic actuators, and other magnetic sensing devices [1,2]. Magnetic anisotropy is directly related to the asymmetry of the local atomic structure. Origin of asymmetry in thin film could be in form of magneto crystalline, magneto elastic and interfacial contribution [3]. Ion implantation is an useful technique to modify the magnetic properties of a thin film. It is a well-controlled method depending on ion fluence and energy, Implantation of O ions in to Fe/Co/(Fe57/Fe)/Si trilayer has been performed to modify its structural and magnetic properties. X-ray reflectivity (XRR) and atomic force microscopy (AFM) measurement indicate that after implantation interface and surface roughness of the film have been increased. XRR measurement of sample implanted at higher fluence shows intermixing at the interface of Fe(top)/Co and Co/Fe57(bottom) layer. MOKE measurement reveals O ion implantation reduces the coercivity of film from 50 Oe to 31 Oe. Ion implantation induces two fold magnetic anisotropy. The saturation magnetic moments of the film after ion implantation have been increased. After ion implantation, the Mössbauer spectrum becomes broadened and suggests the formation of FeCoO and FeCo component at the interface because of ion beam mixing, which enhances the magnetic moment of the film. 1. D B Fenner,,Vac. Sci. Technol. A, 72,1207-1212 (2001). 2. M N Baibich,, Phys. Rev. Lett., 61,2472-2475 (1988). 3. J. Fassbender,, Appl Phys A 77,51 (2003).

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Perovskite : (Session Chairs: Y. K. MISHRA, L POLAVARAPU)
Authors : Min Chen, Huicheng Hu, Di Yang, Linzhong Wu, Qi Pan, Baoquan Sun,* Shuit-Tong Lee,* Yadong Yin, * Qiao Zhang*
Affiliations : Min Chen; Huicheng Hu; Di Yang; Linzhong Wu; Qi Pan; Baoquan Sun; Shuit-Tong Lee; Qiao Zhang Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University Email: Yadong Yin Department of Chemistry, University of California, Riverside

Resume : All-inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals have been regarded as emerging materials in diverse fields due to their excellent photophysical properties. Recently, our group have developed some new synthetic strategies including solvothermal, microwave-assisted, post-treatment and room-temperature injection synthesis methods to prepare colloidal CsPbX3 perovskite nanocrystals. By the manipulation of reaction parameters (surface ligands, reaction kinetics…), CsPbX3 perovskite nanocrystals with controllable morphologies such as nanocube, nanowire, nanoplate, have been synthesized. In addition, the stabilities of such nanocrystals against water, polar solvent, heat and light treatment can be improved by surface engineering. Ligands (trioctylphosphine oxide, 1-octylphosphonic acid) and oxides (SiO2 and ZrO2) have been successfully demonstrated. We believe these work will shed some light on not only CsPbX3 nanocrystals synthesis and their nanocomposite design, but the stability problem-solving.

Authors : Efrat Lifshitz, - Presenting Author (Maya Isarov, Alyssa Kostadinov, Technion – Israel Institute of Technology, Haifa, Israel; Maryna Bodnarchuk, Maksym Kovalenko, from ETH, Zurich, Switzerland; Liang Tan, Andrew Rappe, Pennsylvania University, Philadelphia, USA) Corresponding Author:
Affiliations : Technion - Israel Institute of Technology

Resume : Hybrid organic-inorganic perovskites have become one of the most promising materials in the photovoltaic field. The best performance was found in compounds with general chemical formula, ABX3, when A is either organic or inorganic cation, like methylammonium (MA+), formamidinium (FA+) or Cs+, B is a bivalent metal cation, such as Pb2+ and X is a halide, Cl−, Br−, or I−. The amazing performance of ABX3 perovskites is attributed to their direct band gap, high absorption coefficient, long carrier diffusion length, hot carrier bottleneck, an ambipolar carrier transport property and low production costs. Perovskites have also been demonstrated as suitable materials for detecting visible light, x-ray, or γ-ray. While remarkable observations were reported in recent years, there is a little knowledge about their spin properties and their on the optical and magneto-optical of perovskite materials. The present work describes a research that explored the band-edge properties of CsPbBr3 perovskites, to elucidate the electronic origin for some of the unique phenomena. This compound was selected for the study due to its relative chemical and photochemical stability. The samples were supplied by the group of Prof. Maksym Kovelenko at ETH. The study focused on the investigation of single colloidal nanocrystals (NCs) as well as on bulk structures. The band-edge properties were examined by recording the linearly and circularly polarized micro-photoluminescence spectra in the presence of an external magnetic field up to 9 Tesla. The high resolution gained in the measure of a single NC enabled resolving fine split in the exciton emission at zero magnetic field, which grew gradually with the increase of the field strength. Surprisingly, the split energy grew nonlinearly with the increase of the magnetic field, a fact that indicated a deviation from a linear and from second order corrected Zeeman effects. Theoretical simulations, carried out by a collaborative work with the group of Prof. Andrew Rappe at University of Pennsylvania, revealed the existence of a Rashba effect predominantly at field strength < 4 Tesla, explaining the non-linear behavior. Further on, the circular polarized measurement showed an asymmetry between the σ components, suggesting a partial mixing of one of them with higher electronic states. This point should be further explored in order to gain better understanding in the near future. The Rashba effect emanates in cases experiencing lack or breakage of inversion of symmetry and existence of spin-orbit coupling, both conditions presumably existing in the Perovskites materials, where the small cation A liability induces a crystal distortion and consequent inversion symmetry breaking. Current observations on bulk CsPbBr3 single crystal reflected similar observations for those viewed in analogous NCs, particularly when examined along unique crystallographic direction. In addition, the observations found in the bulk samples indicate a plausible contribution of cubic Rashba effect, which may indicate a mixing of high lying states to the band-edge properties and may support also the asymmetry in the σ emission band patterns as was found in a single NC. This open question will be further investigated in the coming months. In any event, the Rashba effect split the band edge extrema to a k0 a Brillouin point with momentum forbidden transitions, thus, extending the carriers lifetime at the excited state with a large benefit in photovoltaic devices and in x-ray, or γ-ray detectors.

Authors : Stepan Demchyshyn 1, Serdar Saricifci 2, Markus Scharber 2, Siegfried Bauer 3, Martin Kaltenbrunner 1
Affiliations : 1) Soft Electronics Laboratory, LIT, Johannes Kepler University Linz, Altenbergerstr. 69, A-4040 Linz, Austria; 2) Linz Institute for Organic Solar Cells, Johannes Kepler University Linz, Altenbergerstr. 69, A-4040 Linz, Austria; 3) Soft Matter Physics, Johannes Kepler University Linz, Altenbergerstr. 69, A-4040 Linz, Austria

Resume : Halide perovskites are inexpensive and easily processable next generation semiconductors. We here demonstrate perovskite solid-state confinement in nanoporous oxide matrices as a general strategy to control the size of the nanocrystallites (<10 nm) in the strong quantum size effect region. Photoluminescence tuning between near infrared and ultraviolet is achieved by manipulating the size of perovskite crystals through confinement in nanoporous alumina (npAAO) or silicon (npSi) scaffolds [1]. Our novel method of nanocrystalline perovskites preparation within a porous oxide matrix results in device-relevant structure that requires no colloidal stabilization. Low-voltage LEDs with narrow, blue-shifted emission fabricated with perovskite nanocrystallites confined within npAAO thin films support the general concept for next-generation photonic devices. The template-controlled size of the perovskite crystals is quantified in npSi with microfocus high-energy X-ray depth profiling in transmission geometry, verifying the growth of perovskite nanocrystals throughout the entire thickness of the nanoporous films. We study in detail exciton recombination, exciton-phonon interactions and energy trap states in confined and bulk semiconductor films using low temperature photoluminescence spectroscopy down to 3.8 Kelvin. Further areas of application include photon detectors, (polarized) electroluminescent devices, single-photon sources and metasurfaces. Future developments will include increasing the efficiency of the LEDs, exploring their applications in flexible devices and in depth study of the fundamental properties of the confined structures. [1] S. Demchyshyn, J. Roemer, H. Groiss, H. Heilbrunner, C. Ulbricht, D. Apaydin, A. Böhm, U. Ruett, F. Bertram, G. Hesser, M. Scharber, N. S. Sariciftci, B. Nickel, S. Bauer, E. D. Głowacki and M. Kaltenbrunner, “Confining Metal-Halide Perovskites in Nanoporous Thin Films”, Science Advances 3 (8), e1700738 (2017).

Authors : E. Bortchagovsky
Affiliations : Institute of Semiconductor Physics of NAS of Ukraine, pr.Nauki 41, Kyiv 03028, Ukraine

Resume : It is well known that interaction of two resonances results in their hybridization and splitting of crossed dispersion relations. Strong interaction exceeding damping of separated resonances gives so called Rabi splitting. Ellipsometry was used for investigations as this method registers the ratio of the ratio of reflected fields in p- and s-polarization recording in such a way all resonances of the system independently on their polarization. Investigation of layers of monodisperse spherical gold nanoparticles on gold films was made as in standard configuration with external reflection as in Kretschmann configuration with internal reflection. Obtained results allow to build dispersion curves, which demonstrate splitting in the case of interactions of localized plasmon of nanoparticles with surface plasmon of the gold substrate. Interaction of nanoparticles with the substrate lifts the degeneration of localized plasmon on a spherical nanoparticle. Parts of dispersion curves obtained at external and internal reflection join each other what demonstrates that the excitation of surface plasmon via nanoparticles is visible even at external reflection in such a system.

Authors : R. Cichelero, M. V. Kataja, G. Herranz
Affiliations : Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193, Bellaterra, Catalonia, Spain

Resume : Phase-matching conditions are exploited to enable nonreciprocal optical propagation and enhanced magneto-optic responses in magnetoplasmonic systems [1]. Here we show that exploiting diffraction in conjunction with plasmon excitations adds further versatility and flexibility in the design of photonic systems. As a testbed we analysed transverse magneto-optic Kerr (TMOKE) responses in magnetoplasmonic gratings etched into gold/cobalt multilayers [2]. The grating coupler was chosen as the simplest system where we can combine the three distinct phenomena: magneto-optics, diffraction and plasmonics. Angular resolved measurements revealed narrow line-shape plasmon resonances, enabling large diffracted magneto-optical intensity effects. We show that exploiting diffraction in magnetoplasmonic crystals allows unexpectedly large TMOKE responses above that exceed 3% - one of order of magnitude larger than conventional TMOKE. Our results pave the way towards using magneto-optical modulation of SPPs to build non-reciprocal, active photonic components. We anticipate that our results can be used to design more complex diffractive surfaces, such as plasmonic metasurfaces, with the objective to enable creation of novel non-reciprocal photonic devices. [1] V. I. Belotelov et al., Nat.Nanotechnol. 6, 370 (2011). [2] R. Cichelero et al., submitted.

Authors : K.-H. Heinig(1), J. von Borany(1), K.-H. Stegemann(4), T. Prüfer(1), X. Xu(1), W. Möller(1), A. Gharbi(2), R. Titon(2), F. Klüpfel(3), G. Hlawacek(1), L. Bischoff(1), H.-J. Engelmann(1), S. Facsko(1)
Affiliations : 1 Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany; 2 CEA, LETI, MINATEC Campus, F-38054 Grenoble, France; 3 Fraunhofer Inst Integrated Syst & Device Technol, Erlangen, Germany; 4 X-FAB Dresden GmbH & Co. KG, 01109 Dresden, Germany

Resume : Single Electron Transistors (SETs) are an ultra-low power consumption alternative to Field Effect Transistors (FETs). Their room temperature operation is based on two conditions: (i) The Coulomb energy for charging the dot with an electron must exceed kT. This requires Si dot sizes <5 nm. (ii) The tunneling distance between dot and electrodes through SiO2 must be <1.5nm. These requirements are beyond current top-down approaches. Thus, we follow a bottom-up approach: (i) A single Si dot forms self-organized by phase separation of a tiny metastable SiOx volume into a Si precipitate and a SiO2 matrix. (ii) If the tiny SiOx volume is sandwiched between Si, then the single dot becomes self-aligned, i.e. two tunnel barriers form due to condensation of excess Si from SiOx onto the Si/SiO2 interfaces. Here, a CMOS compatible fabrication of vertical-nanowire-based SETs will be presented. Regular arrays of Si nanowires with diameters down to 20nm are fabricated by top-down processes. A SiO2 layer of 7nm thickness is sandwiched between the upper and lower Si of the pillar. This SiO2 is transformed to SiOx(x<2) by ion beam mixing. During subsequent thermal activation (RTA) the dot structure evolves as described above. Experimental and computer simulation results will be presented, and critical fundamental issues of the nanofabrication will be discussed. This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 688072.

Authors : Lakshminarayana Polavarapu
Affiliations : Chair for photonics and optoelectronics, Ludwig-Maximilians-Universität, Munich, Germany Nanosystems Initiative Munich (NIM), Munich

Resume : Perovskite nanocrystals (NCs) are gaining increasing attention in many fields ranging from chemistry to physics and engineering owing to their extremely interesting properties such as high photoluminescence quantum yields, tunable optical bandgap, enhanced stability, large diffusion lengths and shape controllability. Shape-controlled synthesis and their self-assembly into ordered superlattices has emerged as a powerful tool for tailoring the nanoscale optical properties. Such coupled optical and electronic properties can be utilized for the development of novel optoelectronic devices. In this talk, I will present a one-pot shape-controlled synthesis of highly crystalline and monodisperse CsPbX3 (X=Cl, Br and I) perovskite NCs of various morphologies such as nanocubes, nanoplates (NPls), nanowires (NWs) and nanorods (NRs) starting from their precursor powders. [2-5] The morphology of perovskite NCs can be controlled by means of simple chemistry such as Cs/Pb precursor ratios, reaction time and ligand concentration. We discovered that the perovkite NCs spontaneously self-assemble into nanowires or supercrytals (SCs) depending on the reaction conditions. The optical bandgap of the perovskite NCs as well as SCs can be controlled over the entire visible range by varying the halide (Cl, Br, and I) composition. Our work not only provides a facile method for the shape-control of monodisperse perovskite NCs and their self-assembly, but also expands our current understanding of the morphology-dependent optical properties, and open new avenues for the fabrication of highly ordered architectures using perovskite NC building blocks for future optical and optoelectronic devices.

Authors : Xing Xing, Yumeng Liu, Hong Meng, Wei Huang.
Affiliations : Northwestern Poyltechnical University(Shenzhen) ; Peking University(Shenzhen)

Resume : Nanostructure application in electrochromic electrode can effectively enhance the ion diffusion efficiency , which can greatly optimize their contrast and switching. This phenomenon has been proved both in inorganic material and organic material. In this presentation, we will focus on the organic nanoparticles engineering in electrochromics, study how the nanostructure affects the electrochormic performance. Different electrolyte will also be discussed. Both of the problems are very important steps towards the industrail appllication of organic electrochromics.

Perovskite : (Session Chairs:Y. K. MISHRA, L. POLAVARAPU, J. ADAM, M. ELBAHARI)
Authors :
Affiliations : Istituto Italiano di Tecnologia, Via Morego, 30 16163 Genova, Italy.

Resume : Inorganic perovskite nanocrystals have recently emerged as a highly promising material in light emission due to color tunability by chemical composition and quantum confinement, and bright emission from nanocrystal films with photoluminescence quantum yields up to unity has been demonstrated. [1,2] In this talk the photo-physical properties of perovskite nanocrystal in solution and in thin films will be discussed. [3] Plasmonic resonances of metal/dielectric multilayers can be used to enhance the emission and radiative rate of the perovskite nanocrystals spincoated on their surface. We demonstrate four-fold emission enhancement of a film of CsPbBr3 nanocubes [4] deposited on such layered metamaterial structures, and highlight how the plasmonic resonances can be tuned to the emission and absorption bands of the emitter.[5] Quantum confinement in CsPbBr3 nanoplatelets results in blue emission and films with 25 % PLQY are be obtained by spin-coating. The nanoplatelets in such films can be transformed to green emitting nanobelts by high intensity UV light exposure. [6] The transformed films manifest extremely stable emission and are robust to treatment with different solvents, which enables the fabrication of all-solution processed light emitting diodes. References [1] Nano Lett. 15, 3692 (2015). [2] Nature Commun. 6, 8056 (2015). [3] J. Phys. Chem.Lett. 8, 2725 (2017). [4] J. Am. Chem. Soc. 140, 2656 (2018). [5] ACS Photonics 5, 2287 (2018). [6] ACS Nano 11, 10206 (2017).

Authors : Mickael D. Tessier,a Edwin A. Baquero,b Dorian Dupont,a Valeriia Grigel,a Yannick Coppel,c Zeger Hens,a Céline Nayral,b Fabien Delpech,b
Affiliations : a: Physics and Chemistry of Nanostructures and Center for Nano and Biophotonics, Ghent University, Ghent, Belgium. b: Université de Toulouse, INSA, UPS, CNRS, Laboratoire de Physique et Chimie des Nano-Objets, Toulouse, France. c: Laboratoire de Chimie de Coordination, CNRS, UPR 8241, Université de Toulouse, Toulouse, France.

Resume : CdSe based QDs have been intensively studied, however, due their toxicity Cd-based materials are not acceptable for real-life applications. Indium phosphide (InP) based QDs represent the most advanced alternative without toxic heavy metals. Nevertheless, for industrial applications, the photoluminescence quantum yield (PLQY) and the emission linewidth (FWHM) of InP QDs have to be significantly improved. The analysis of InP specificities shows that in contrast to their CdSe analogues, the InP QDs suffers from a high oxophilicity. This leads a strong tendency to oxidize and results in the formation of an amorphous phosphate layer at the surface of the InP QDs either during the synthesis or the shelling (often with ZnS). The role and the influence of this oxidation on the optical properties (PLQY and FWHM) is still a matter of controversy and the definitive answer has so far been precluded because of the lack synthesis method allowing the access to comparable oxide-free samples. In this presentation, we will describe our new approach to prepare oxide-free InP core and InP/ZnS core/shell QDs. Then, we will compare the structural (using XRD, TEM, MAS NMR) and the optical properties (UV-Vis and PL) of oxidized vs. oxide-free samples. The use of the same InP QDs core for the preparation of the samples provides fully comparable data and will thus allow unraveling for the first time the influence of phosphate at the core/shell interface.

Authors : Dr. Sukyung Choi, Dr. Jaehyun Moon, Dr. Hyunso Cho, Dr. Byuong-Hwa Kwon, Dr. Namsung Cho, Prof. Sungjee Kim, and Dr. Hyunkoo Lee
Affiliations : Flexible Device Research Group, Electronics and Telecommunications Research Institute (ETRI), Daejeon 34129, Republic of Korea

Resume : Colloidal quantum dots (QDs) have received great interest as promising active materials in optoelectronic devices, owing to their unique optical properties such as broad absorption ranges, high extinction coefficients, sharp symmetric emission peaks and tunability of the band gap. Because of the small size of QDs, their physical and chemical properties are highly affected by the surface environment. Therefore, appropriate selection of surface ligands is important for specific applications such as QD light-emitting diodes (QD-LEDs). QD-LEDs have been developed in recent years as the next-generation, low-cost, solution-processible, full-color displays. We have studied the effects on performance of QD-LEDs when the surface ligands were modified. The short length of molecule was selected as a new surface ligand and it was functionalized on QDs’ surface by exchange from long hydrocarbon chain original surface ligands. Both the short molecular length and appropriate HOMO level of ligand improve the hole transport to QDs. All three fundamental colors, red-, green-, and blue-emitting QD-LEDs functionalized with this short length molecule showed enhanced current efficiencies, power-efficiencies and low turn-on voltages compared with the QD-LEDs capped with the original surface ligands. They showed narrow emission peaks and 159% covered the NTSC color gamut. This is an easy and efficient surface-modification strategy for developing high-performance QD-LEDs in the future. -This work was supported by Institute for Information & communications Technology Promotion (IITP) grant funded by the Korean goverment (MSIT) (2017-0-00065, The core technology development of high performance materials and devices for volumetric display)

Authors : He Huang, Andrey L. Rogach, Jochen Feldmann
Affiliations : 1. Dr. He Huang, Prof. Dr. Jochen Feldmann Lehrstuhl für Photonik und Optoelektronik, Department für Physik und Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität München, Amalienstr. 54 (2nd floor) 2. Prof. Dr. Andrey L. Rogach, City University of Hong Kong

Resume : Lead halide perovskites, both in form of thin films and colloidal nanocrystals (NCs), have attracted a lot of attention as components of solar cells, light-emitting diodes, and photodetectors. Size, shape, composition and thus optical properties of perovskite NCs can be conveniently tuned by controlling reaction parameters such as precursor concentration, temperature, ratio of halide ions for mixed compositions, as well as via post-synthetic treatment.[1] The understanding of the formation mechanism of perovskite NCs is crucially important for the further optimization of their synthesis. The new and reliable synthetic route is also needed in the field. Besides what we already discover for the formation mechanism of CH3NH3PbBr3 before, we future explore the formation for CsPbBr3.[2] We developed a microwave-assisted slowed-down synthesis of CsPbBr3 perovskite NCs, which retards the reaction and allows us to gather useful insights into the formation mechanism of these nanoparticles, by examining the intermediate stages of their growth.[3] The formation mechanism based on the information we obtained, indicating first the formation of a bromoplumbate ionic scaffold, with Cs-ion infilling lagging a little behind. We also introduce new synthetic route for obtain perovskite NCs. 1. Huang, H., Polavarapu, L., Sichert, J. A., Susha, A. S., Urban, A. S., Rogach, A. L. NPG Asia Mater. 2016 8, e328 2. Huang, H., Raith, J., Kershaw, S. V., Kalytchuk, S., Tomanec, O., Jing, L., Susha, A. S., Zboril, R., Rogach, A. L. Nat. Commun. 2017 8, 996 3. Li, Y., Huang, H., Xiong, Y., Kershaw, S., Rogach, A. L. Angew. Chem. Int. Ed. 2018, DOI: 10.1002/anie.201713332

Authors : Mindaugas Karaliūnas, Evelina Pozingytė, Jan Devenson, Renata Butkutė, Andres Udal, Gintaras Valu¨is
Affiliations : Center for Physical Sciences and Technology, Saul?tekio Av. 3, 10257 Vilnius, Lithuania; Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia

Resume : Parabolic quantum wells (PQWs) are known as a promising candidate for a compact efficient terahertz (THz) source. PQW has equidistant quantum energy levels (QELs) that can be designed to be separated by few meV to meet THz frequency range. Moreover, PQWs are little sensitive to applied electric field and thermal influence. To enhance the efficiency and power of THz emission from PQWs, the new approach is proposed by employing depopulation of the lowest QEL of PQW. The performance of the device is modeled solving the Schrödinger and rate equations taking into account different transition time constants for scattering mechanisms. The pumping of the device is realized through the photoexcitation (band-to-band transitions). The carriers are emitting THz quanta by intersubband transitions down to the lowest QEL. The fast depopulation of the lowest QEL of PQW leads to THz emission enhancement by overcoming the carrier crowding effect. Two designs are considered for 2.5 and 7 THz emission. Inclusion of additional quartic term in Al content distribution was important to compensate the influence of electron effective mass change on QELs separation. Three depopulation mechanisms - the sweep-out by reversed voltage, re-excitation with MIR laser of doped PQWs, and introduction of quantum dot in the PQW are considered. The findings suggest that these depopulation mechanisms in AlGaAs/GaAs PQWs leads to radiation enhanced efficient compact incoherent THz source - THz torch.

Authors : Woo-Gwang Jung, Fatima Tuz Johra
Affiliations : School of Materials Science and Engineering, Kookmin University, Seoul, Korea

Resume : Unlike graphene, black phosphorus (BP) is one of the promising materials to be used in many optical and electronic field. Bandgap can tunable depending on its number of layer, which made this two dimensional material a good candidate for future application. In 1914, BP was synthesized from white phosphorus by Bridgeman. It was high pressure synthesis method. Red phosphorus (RP) is more convenient to synthesize BP, as RP is not much reactive at room temperature. In this study, we synthesized BP from RP in presence of tin and iodine. All of these materials are poured into a quartz ampoule inside a glove box and then sealed. The ampoule was heated in a box furnace at sequential temperature in argon atmosphere. The full process was done in low pressure of Ar. Ribbon like BP has formed by vapor transfer method. Synthesized BP has characterized with FE-SEM which shows the formation of multilayered BP. XRD shows the synthesized BP is well crystalline with orthorhombic structure, whereas RP was amorphous. Raman spectra of synthesized BP also done to confirm the formation of BP.

Authors : Mohammad Bashirpour, Matin Forouzmehr*, Saman Ghorbani, Mohammadreza Kolahdouz, Mohammad Neshat
Affiliations : School of Electrical and Computer Engineering, Faculty of Engineering, University of Tehran, Tehran, Iran.

Resume : In the last decade, THz technologies and applications have attracted lots of attention because of its unique properties such as non-ionizing nature, minimal effect on human body and penetration through a wide variety of materials (paper, wood, plastic, and fabric). These valuable properties have made THz technology a great candidate in medical imaging, security imaging, biochemical spectroscopy, nondestructive test, and others. One of the most common ways of generating THz wave is utilizing photoconductive antennas (PCAs). THz PCA despite of its advantages, such as room temperature operation, and compact design broadband radiation acquires low optical to THz efficiency that limits its applications. Terahertz photoconductive antenna incorporated with ZnO nanorods, gold nanodisk array and disordered plasmonic nanostructure have been simulated and fabricated using electron beam lithography, combined with optical lithography and standard CMOS technology fabrication technology. Experimental results showed that using ZnO nanorods, gold nanodisk array and disordered plasmonic nanostructure results in 2, 5.6 and 2 times enhancement of THz peak signal compared to conventional PCA with 200 nm Si3N4 antireflection coating, respectively. In addition, THz waves with the spectral range between 0.1-2.5 THz with signal-to-noise ratio of 60-70 dB obtained using 800 nm femtosecond laser.

Plasmonics : (Session Chairs:Y. K. MISHRA, L. POLAVARAPU, J. ADAM, M. ELBAHARI, D. K. AVASTHI)
Authors : Yih Hong Lee,1* Hiang Kwee Lee,1,2 Yijie Yang,1 Ruibin Jiang,3 Jianfang Wang,3 Xing Yi Ling1*
Affiliations : 1 Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371. ‎2 Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) 2 Fusionopolis Way, Innovis, Singapore 138634. 3 Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.

Resume : Shape-controlled nanoparticles can be assembled into structurally diverse superlattices. However, it remains challenging to control the organization of one nanoparticle morphology into multiple superlattices over large areas. Here, we demonstrate the concept of ‘one nanoparticle, multiple plasmonic metacrystals’ using Ag octahedra and nanocubes. We tailor the nanoscale surface wettability of the Ag octahedra and nanocubes using a family of thiol-terminated molecules. Subsequent assembly of these nanoparticles at the oil/water interface gives rise to multiple plasmonic metacrystals. Increasing the surface hydrophobicity of the nanoparticle surfaces leads to increasingly open metacrystals with packing densities as low as 24 %. At this packing density, the nanoparticles are standing on their vertices in their respective plasmonic metacrystals. Notably, we can achieve large areas of these plasmonic metacrystals despite their structural instability. A structure-to-function characterization for these metacrystals shows that the lowest packing density metacrystals generates the highest surface-enhanced Raman scattering (SERS) enhancement factors for both the metacrystals of nanocubes and octahedra. Numerical simulations indicate that this strong enhancement arises from the large-area field delocalization within the metacrystals. Our findings imply that packing the highest number of NPs within a given area will not always generate the strongest SERS enhancement.

Authors : Tiziana Cesca, Boris Kalinic, Niccolò Michieli, Ionut Balasa, Carlo Scian, Giovanni Mattei
Affiliations : NanoStructures Group (NSG), Dept. of Physics and Astronomy, University of Padova, Padova, Italy

Resume : Plasmonic metamaterials with engineered optical density of states can be particularly interesting in nanophotonics or quantum optics for controlling the emission efficiency of suitable quantum emitters (QE) coupled in near-field. Among different possible QEs, rare-earth (RE) ions (like Er3+ and Eu3+) are particularly interesting for their intense room temperature emission as a two-level system in the visible or near-infrared spectral region. In this work, we studied the coupling of RE QEs with plasmonic nanostructures to achieve quantum emission enhancement. Two classes of ordered metamaterials were investigated: (i) nanohole arrays (NHA) and (ii) hyperbolic metamaterials (HMM) in form of periodic multilayers. We coupled Er3+ ions emitting at 1.5 microns with the extraordinary optical transmission (EOT) of a Au NHA. This resulted in a reduction of the emission lifetime by a factor 2-3 (in quantitative agreement with FEM simulations), together with external quantum efficiency of about 0.9, with reduced losses and a high directionality in the emission pattern. We investigated also the coupling between Eu3+ emitting at 615 nm and a HMM made of Au-Al2O3 periodic multilayer. We found that when the metamaterial is designed to be in its hyperbolic regime, the measured lifetime strongly decreses (up to a factor 3) with a concomitant high increase of the PL intensity, whereas for the same metamaterial in the conventional elliptical regime the decrease is significantly smaller.

Authors : Ehsan Rezvani, Oral Ualibek, Brendan Bulfin, Gulnar Sugurbekova, Georg S. Duesberg, Igor Shvets
Affiliations : CRANN, Trinity College Dublin, Dublin, Ireland National Laboratory Astana, Nazarbayev University, Astana, Kazakhstan German Aerospace Center, Koln, Germany

Resume : Plasmonic nanostructures offer great enhancement of the Raman signal due to the strong confinement of the electromagnetic field. Thus, they are considered as suitable candidates for surface-enhanced Raman spectroscopy (SERS). In this work, we present an alternative fabrication route, called the glancing angle deposition (GLAD), for tunable fabrication of plasmonic self-organised Ag nanoparticle arrays aimed at SERS. Using the GLAD technique, the inter-particle distance within the arrays can be made as small as 1 nm. Moreover, the plasmonic resonance can be precisely tuned over the whole visible range. The GLAD method can be up-scaled; and when a transparent substrate is used, it enables various measurement geometries. The enhancement factor for the employed probe molecule in this study, rhodamine 6G, is estimated to be in the order of 10E8. It is noted that the nature of the GLAD-made substrates leads to the polarisation dependence of the signal enhancement. The polarisation studies show a stronger enhancement along the nanoparticles chain.

Authors : Moheb Abdelaziz (1,2), Mady Elbahri(1,2)
Affiliations : 1- Nanochemistry and Nanoengineering Institute for Materials Science Faculty of Engineering Kiel University 2- Nanochemistry and Nanoengineering School of Chemical Engineering Department of Chemistry and Materials Science Aalto University

Resume : Absorptivity is the property by which plasmonic dipoles are known rather than reflectivity. Here, we introduce and utilize the so far unknown specular reflection and the Brewster effect of ultrafine plasmonic dipoles and metaparticles as the basis of new design rules for advanced applications. A setup of ''Plasmonic metaparticles on a black body'' is exhibited and used for the design of a tailored perfect-colored absorber and for visual detection of surrounding medium dielectrics that isn't promptly done by extinction plasmonics. The Plasmonic Brewster Wavelength (PBW) effect is exploited as a new platform for the naked-eye and bulk biodetection of analytes. The method works based on slight changes in molecular polarizability which cannot be recognized with currently known Plasmon resonance techniques. As a particular feature the clinical applicability of the PBW strategy is exhibited for the detection of bulk refractive index changes in healthy and diseased human serum exosomes. Moreover, here a simple, low cost and scalable sputtering-based fabrication method utilized which avoids complications of lithography or precise alignment of light coupling for biodetection.

Authors : Annett Thøgersen, Torunn Kjeldstad, Ingvild J. T. Jensen, Marit Stange, Ole Martin Løvvik, Augustinas Galeckas, Edouard Monakhov, and Spyros Diplas
Affiliations : Annett Thøgersen;Torunn Kjeldstad; Ingvild J. T. Jensen; Marit Stange; Ole Martin Løvvik; Spyros Diplas: SINTEF Industry, P.O.Box 124 Blindern, 0314 Oslo, Norway Torunn Kjeldstad; Augustinas Galeckas; Edouard Monakhov: Department of Physics, Centre for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo, Norway.

Resume : Nanostructured materials, including nanowires, particles and tunnels, have shown to have unique optical properties compared to their bulk counterparts, like increased band gap, indirect to direct band gap transition, and an increased charge carrier concentration. Such nanostructures can therefore be interesting for use in optoelectronic devices, such as solar cells and sensors, as well as for energy storage purposes. Utilizing the immiscibility between aluminium and silicon resulted in a self-organizing process creating Al nanowires in an amorphous silicon (aSi) matrix when thin films were prepared by magnetron co-sputtering. Removing the Al nanowires by etching created an aSi matrix with nanotunnels, similar to a honeycomb structure. In order to investigate their optical properties, reflectance and simple calculations have been carried out on the Al nanowires with various sizes. The surface plasmon nodes of the Al nanowires have then been investigated and mapped on the nanoscale using electron energy loss spectroscopy with transmission electron microscopy. In addition, the band gap of the surrounding aSi have been measured.

Graduate Student Award (GSA) Presentations : (Session Chairs:Y. K. MISHRA, L. POLAVARAPU, J. ADAM, M. ELBAHARI, D. K. AVASTHI)
Authors : Charlynn Sher Lin Koh,[a] Hiang Kwee Lee,[a], [b] Xuemei Han,[a] Howard Yi Fan Sim,[a] Xing Yi Ling[a] *
Affiliations : [a] C.S.L. Koh, Dr. H.K. Lee, Dr. X. Han, H.Y.F Sim, Prof X.Y. Ling Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link, Singapore 637371 E-mail: [b] Dr. H.K. Lee Institute of Materials Research and Engineering Agency for Science, Technology and Research (A*STAR) 2 Fusionopolis Way, Innovis, #08-03, Singapore 138634

Resume : Achieving accurate and ultratrace detection of gas/vapor is impervious as toxins are deadliest in gaseous form due to its acute toxicity upon inhalation, high mobility and difficulty in containment. However, current gas detection techniques still face several limitations such as low sensitivities and susceptibility to give false positives. Herein, we design a plasmonic nose based on zeolitic imidazolate framework (ZIF)-encapsulated Ag nanocubes array, to directly sniff out toxic volatile organic compounds (VOCs) vapors from air and realize ultratrace recognition of these vapors down to ppm level. Our plasmonic nose consists of multifaceted and synergistic strategies – (1) optimizing preconcentration of gas volume conferred by ZIF, and (2) intensifying plasmonic hotspots by modulating the interparticle spacing of adjacent Ag nanocubes. The plasmonic nose is capable of in-situ adsorption kinetics and quantitative detection of non-adsorbing toluene vapor from 200 to 20000 ppm. This detection range is the within regulatory limits and covers the concentrations where human exposure at these levels could lead to health hazards ranging from throat/eye irritation to even death. The vibrational fingerprint obtained from SERS also permits the molecular recognition of a series of VOCs such as chloroform and 2-naphthalenethiol, effectively eliminating false positives. Our plasmonic nose also possess excellent recyclability simply via vacuum regeneration. This multifaceted approach provides a paradigm shift in the current MOF-SERS systems, and can push the detection capability beyond boundaries, shaping future toxic gas regulations.

Authors : S. Goswami, T. Venkatesan
Affiliations : NUS Nanoscience and Nanotechnology Institute (NUSSNI)

Resume : Non-volatile memories will play a decisive role in the next generation of digital technology. Flash memories are currently the key player in the field, yet they fail to meet the commercial demands of scalability and endurance. Resistive memory devices, and in particular memories based on low-cost, solution-processable and chemically tunable organic materials, are promising alternatives explored by the industry. However, to date, they have been lacking the performance and mechanistic understanding required for commercial translation. Here we report a resistive memory device based on a spin-coated active layer of a transition metal complex, which shows high reproducibility ~350 devices), fast-switching <30 ns), excellent endurance (~10^12 cycles), stability (>10^6 s) and scalability (down to ~60nm^2). In situ Raman and ultraviolet–visible spectroscopy alongside spectroelectrochemistry and quantum chemical calculations demonstrate that the redox stateof the ligands determines the switching states of the device whereas the counterions control the hysteresis. This insight may accelerate the technological deployment of organic resistive memories. [1] Goswami, Sreetosh, et al. "Robust resistive memory devices using solution-processable metal-coordinated azo aromatics." Nature Materials 16.12 (2017), 1216. [2] Valov, Ilia, and Michael Kozicki. "Non-volatile memories: Organic memristors come of age." Nature Materials 16.12 (2017), 1170.

Authors : Saskia Fiedler Dr. Laurent O. Lee Cheong Lem Dr. Cuong Ton-That Prof. Matthew R. Phillips
Affiliations : University of Technology Sydney

Resume : Light extraction from ZnO-based devices can be enhanced via metal nanoparticles (NPs). In this work, the enhanced UV emission of metal NP-coated ZnO was systematically studied using cathodoluminescence (CL) and photoluminescence (PL) spectroscopy. Two metals – 5nm Au NPs and 2nm Al – were deposited onto ZnO nanorods (NRs), and single crystals. CL and PL spectra of uncoated ZnO exhibited a sharp UV emission at 3.36 eV from excitonic recombination, and a broad visible defect-related emission. Au-coated ZnO showed a 4-fold UV enhancement, while Al increased the UV emission up to 10 times, with highest enhancement near the surface. Both metals reduced the excitonic lifetime, which indicates the creation of an additional, faster recombination path, enhancing the spontaneous emission rate. For Al, this can be via localized surface plasmons (LSPs), as its plasmon resonance energy (LSPR) is in the UV. Au’s green LSPR is spectrally too far to allow direct LSP-exciton coupling, suggesting faster recombination via interband transitions in Au. Temperature-dependent PL of Al-coated ZnO showed highest enhancement at 80K, where ZnO’s emission is dominated by free excitons (FX). This strongly suggests that the LSPs couple more efficiently to FX than to bound-excitons. The enhancement of Au-coated ZnO is temperature-independent. In conclusion, interband transitions in Au can be responsible for the enhanced UV emission, while the enhancement mechanism in Al was assigned to LSP-exciton coupling.

Authors : Michael Sachs1, Ji-Sang Park2, Ernest Pastor1,3, Andreas Kafizas1, Laia Francàs1, Sheraz Gul3, Min Ling4, Chris Blackman4, Junko Yano3, Aron Walsh1,5, and James R. Durrant1
Affiliations : 1 Department of Chemistry, Imperial College London, London, SW7 2AZ, U.K. 2 Department of Materials, Imperial College London, London, SW7 2AZ, U.K. 3 Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, U.S.A. 4 Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, U.K. 5 Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea

Resume : Semiconducting metal oxides are the most widely used photocatalysts in the field of sunlight-driven fuel generation owing to their cost effectiveness, good stability, and natural abundance. However, the lack of visible light absorption leads to severe mismatch with the solar irradiance spectrum and thus limits the photocatalytic performance of many metal oxides. As a result, the introduction of oxygen vacancies is becoming an increasingly popular strategy to extend the light absorption of these systems into the visible range.1,2 In this study, we investigate the charge carrier dynamics such highly oxygen-deficient metal oxides for the case of nanostructured WO3. The high degree of oxygen deficiency introduces defect states throughout the band gap which give rise to visible and near-infrared light absorption, resulting in an intense blue coloration of the material. We herein use transient absorption spectroscopy (TAS) to probe the kinetics and lifetimes of photogenerated charge carriers over timescales, ranging from femtoseconds to seconds after light absorption. To compare the excited state evolution of regular WO3 thin films to that of highly oxygen-deficient WO3, we distinguish between band gap excitation using UV light and the direct excitation of sub-band gap states using visible to near-infrared light. This comparison allows us to elucidate the charge recombination mechanisms as a function of both oxygen vacancy density and excitation wavelength. To shed light on the local bonding environment at different oxygen vacancy densities, we perform first-principles density functional theory (DFT) calculations. Taken together, the results presented herein illustrate opportunities and challenges of oxygen-deficient metal oxides for solar energy applications. (1) Chen, X.; Liu, L.; Yu, P. Y.; Mao, S. S. Increasing Solar Absorption for Photocatalysis with Black Hydrogenated Titanium Dioxide Nanocrystals. Science 2011, 331, 746–750. (2) Wang, G.; Ling, Y.; Wang, H.; Yang, X.; Wang, C.; Zhang, J. Z.; Li, Y. Hydrogen-Treated WO3 Nanoflakes Show Enhanced Photostability. Energy Environ. Sci. 2012, 5, 6180–6187.

Authors : Naveen Tiwari; Ankit; Mohit Kulkarni; Nripan Mathews
Affiliations : Naveen Tiwari, Ankit, Mohit Kulkarni: School of Materials Science and Engineering, Nanyang Technological University, 637553, Singapore Prof. N. Mathews: School of Materials Science and Engineering, Nanyang Technological University, 637553, Singapore Energy Research Institute @ NTU (ERI@N), Nanyang Technological University, 637553 Singapore

Resume : Challenges associated with mechanical fracture of electrical conductors has hindered the realization of truly flexible high performance wearable electronics. Here, transparent healable electrodes have been developed and examined to alleviate these problems. The composite electrode features a layer of interconnecting AgNWs network on a polyurethane film modified with Diels–Alder adducts (PU-DA). Surface modification using hydrophilic molecules improved adhesion of the AgNWs network and resulted in mechanically robust flexible electrodes with a figure of merit sheet resistance of 13.3 Ω/sq and 77% transmittance at 550 nm. Transparent and flexible healable heaters (TFHH) with good mechanical and thermal stability were fabricated using these electrodes for potential applications in thermochromics, electrically driven displays and defrosters. The PU-DA TFHHs exhibited high Joule heating temperatures of 102 °C with a low operation voltage (6 V), fast thermal response (150 s) and enhanced robustness to endure large repeated mechanical strain for over 500 bending cycles with small variance in resistance(<10%). After deliberate damage by a knife cut, the electrodes healed and recovered back to its original conductivity via a simple heat treatment at 120 °C. Uniquely, the healing process can also be triggered by utilizing electrical power.

Authors : Masashi Ota, Yuta Tonooka, Tomohiro Hirano, Yudai Kikuchi, Mitsuo Fukuda
Affiliations : Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology

Resume : We propose a novel gap-plasmon excitation structure for photonic integrated circuits. The structure consists of a Au stripe and tapered gap for refractive index matching to a gap plasmonic waveguide and was fabricated at the top surface of a dielectric-stripe-type plasmonic waveguide deposited on a Au film. The width of the gap-plasmonic waveguide is designed to 50 nm by considering fabrication accuracy. Propagating surface-mode plasmons, confined into the dielectric-stripe waveguide, are localized at the corner of the Au stripe. Then, the localized lateral plasmons are converted to the orthogonal-polarized gap-plasmonic mode by increasing the effective refractive index of the gap waveguide using the tapered gap. The intensity ratio of the gap-waveguide mode to the dielectric-stripe-waveguide mode was estimated to be of 0.75 using the finite-difference time-domain method, and the high converting efficiency was confirmed. The proposed structure was fabricated by patterning a 50-nm-thick Au film on the 600-nm-wide dielectric stripe plasmonic waveguide using focused ion beam milling technique. We have experimentally observed the gap-mode plasmonic intensity distribution using scanning near-field optical microscopy and confirmed the high conversion efficiency. The proposed novel excitation structure will pave the way for higher density photonic integrated circuits.

Authors : Mahima Sharma1, Kannikka Behl2,Subhasha Nigam2, D.K Avasthi1 *, S.K. Srivastava3, Yogendra Kumar Mishra4, Rainer Adelung4, Monika Joshi1,*
Affiliations : 1Amity Institute of Nanotechnology, Amity University, Noida, Uttar Pradesh, India 2Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, India 3Department of Physics, Indian Institute of Technology Kharagpur, India 4Functional Nanomaterials, Institute for Materials Science, Kiel University, Kaiserstr. 2,24143, Kiel, Germany

Resume : Produced water (PW) represents the largest waste stream integrated with oil exploration, which is one of the crucial environmental and health issues. In this study, we report the synthesis of an effective and novel magnetic nanohybrid, ZnO-Tetrapods/Iron Oxide Nanorods (ZnO-T/Fe2O3-NR) using hydrothermal process. The synthesized nanohybrids was applied as a magnetic adsorbent for remediation of lead (cationic) and chromium (VI) (anionic) metal ions and separation of oil from produced water. The structural, chemical and magnetic characterizations of synthesized nanohybrids were performed using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, Vibrating Sample Magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). These characterizations suggested successful preparation of nanohybrids consisting of Fe2O3-NR coated on the surface of ZnO-T. The as-synthesized nanohybrids exhibited enormous surface area and high magnetic saturation value, indicating its exceptional adsorption ability and magnetic separation. The treatment capability was investigated in terms of removal of heavy metal ions, oil sorption studies, Total Dissolved Solids (TDS) and Chemical Oxygen Demand (COD). The mechanism for the adsorption was explicated by exploring different adsorption kinetics and isotherms models. Interestingly, as-prepared nanohybrids demonstrated extraordinary remediation capacity toward removal of cationic and anionic heavy metal ions, compared to ZnO-T. Overall, the findings inferred that this nanohybrid can be employed for effective water reclamation from produced water.

Authors : Payal Manzhi1, Reena Kumari2, Md. B. Alam2, G.R. Umaapathi3, Richa Krishna1, Sunil Ojha3, Ritu Srivastava2 and O.P. Sinha1*
Affiliations : 1Amity Institute of Nanotechnology, Amity University, UP, Sector-125, Noida 201303, India 2 National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi- 110012, India 3Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi – 110067, India *E-Mails:,

Resume : Mg and Ni doped ZnO and pure ZnO nanostructures have been synthesized by a simple and cost effective wet chemical / hydrothermal method for its potential application in Organic Light Emitting Diodes (OLED). Studies have been undertaken for structural as well as optical properties of ZnO after Mg or Ni doping with various concentrations. Field Emission Scanning Electron Microscopy with Energy-dispersive X-ray analysis reveals the morphology and chemical composition of nanostructures and indicated the different structure for ZnO and with doping it’s converted into the multi facet structure. X-ray diffraction reveals the pure hexagonal phase of the wurtzite structure of ZnO and finds other peaks related to Mg and Ni. UV–Visible suggested the exciton characteristic at room temperature and band gap variation while Photoluminescence spectra reveal two different regions (ultraviolet and blue). Synthesized materials have been blended with Poly [9, 9-dioctylfluorene-2, 7-diyl] (PFO) and prototype OLED has been fabricated using these materials as an emissive layer. Electroluminescence spectra show prominent blue emission at 433nm, 460 nm and 490 at 10V. Current-Voltage (I-V) curve reveal that the stability of OLED device at 20% of doping with Mg and 1% of doping with Ni as compared with pristine PFO device.

Authors : E. Feddi (1,*), A. El Aouami (1), O. Mennaoui (1), M. EL Haouari (2) and F. Dujardin (3)
Affiliations : (1) (LaMCScI), Group of Optoelectronic of Semiconductors and Nanomaterials ENSET, Mohammed V University in Rabat, Rabat, Morocco. (2) Centre Régional des Métiers de l'Education et de Formation (CRMEF), Tanger, Morocco. (3) Université de Lorraine, LCP-A2MC, 57000 Metz, France *email :

Resume : Binding energy and photo-ionization cross section of an off center single shallow dopant in core/shell have been investigated. A variational treatment is developed in the framework of the effective-mass theory, including the effects of interaction between the charge carriers and the longitudinal-optical (LO) phonons and by considering the central-cell correction. The effects of the core and shell sizes, the position of the ionized donor in the shell region and the nature of the dopant are analyzed. Quantitative results are given for quantum dots of Si, GaP and ZnSe coated by SiO2 material. This analysis contributes to understand the external control of the optoelectronic properties of core/ shell structures in order to produce new devices for new applications.

Authors : (1) E. Augendre, F. Piegas Luce, L. Benaissa, J. Widiez, N. Bernier, C. Licitra, N. Chevalier, D. Mariolle, P. Gergaud, E. Rolland, C. Taillandier, J.-S. Moulet, Y. Lamy, F. Servant, (2) W. Favre, J. Stendera, G. D’Alonzo, C. Roux, (3) J. Botsoa, P. Desgardin, M.-F. Barthe
Affiliations : (1) Univ. Grenoble Alpes, CEA, LETI, 38000 Grenoble, France (2) Univ. Grenoble Alpes, INES, 73375 Le Bourget du Lac, France (3) CEMHTI-CNRS, 45071 Orléans, France

Resume : In devices such as photomixers or insulated gate bipolar transistors, the limitation of minority carrier lifetime (MCL) enables high frequency operation. This has triggered the investigation of lifetime killers (LK) such as noble metal atoms and irradiation-induced defects in silicon lattice. In these approaches, however, it is difficult to confine LK due to their diffusion or to the extension of irradiation damage in the Si matrix. In this paper, we characterize polycrystalline silicon as LK. Focusing on lowly doped p-type Si capped with 1.2 µm polycrystalline Si layer, we used several characterization techniques to relate morphology and LK properties. Quasi Steady State PhotoConductivity measurements indicate effective MCL reduction by more than 100x. TEM reveal a distinct interfacial morphology. The surface of LK layer gives photoluminescence response that relates to the combined contributions of several types of dislocations. Scanning Spreading Resistance Microscopy reveals grain boundaries and dislocations in higher density near the deep interfacial layer. X-Ray Diffraction yields dislocation density at the sample surface above 10^10 /cm² and near 10^12 /cm² at the bottom. Modelling positron annihilation response requires considering two distinct defective layers, including the deep interfacial region with enhanced positron-electron recombination on larger defects than Si divacancies.LK layer efficiency mostly owes to the interfacial defect-rich layer. The ECSEL Reference project has funded this work.

Authors : Hojun Ryu, Chil Seong Ah, Jae Bon Koo, Ju Hee Song
Affiliations : Electronics and Telecommunications Research Institute

Resume : Electrochromic devices have been focused for their very unique property of changing transmittance by applied external electric field past decades. Especially in the point of energy saving view, the smart windows adopting electrochomic devices have been studied by many researchers and groups. The electrochromic devices are very capable to control the sunlight which giving thermal effect to the indoor environment as changing the color also. However in order to use the smart windows with electrochromic devices it should be shown good long term stability without deterioration their properties. In case of using liquid electrolyte, the electrochromic devices have been easily affected to lower their grade of long term use by incident sunlight. Therefore we studied the long term stability of the electrochromic devices using gel electrolyte to investigate the feasibility for smart window application. We used WO3 nanostructured film as a cathodic electrode and Prussian blue thin film as a anodic electrode by spin coating on ITO glasses of 105 mm x 105 mm. As we fabricated PVB (Polyvinyl butyral) with 1.1% lithium bis-trifluoromethanesulfonimide for gel electrolyte the full cell of electrochromic devices finalized by injection of the electrolyte. The fabricated electrochromic devices have been driven by /- 1.5 volts for bleaching and darkening process within 30 seconds for each change. The lowest transmittance was 9.1 % and the maximum was 79.7 % after 10,000 cycles.

Authors : Yash Gupta a,Mrinal Poddara, Mahima Sharmaa, Subhasha Nigam b , D K Avasthi a, Yogendra Kumar Mishrac , Rainer Adelungc, Monika Joshi a,*
Affiliations : aAmity Institute of Nanotechnology, Amity University, Sector 125 Noida b Amity Institute of Biotechnology, Amity University, Sector 125 Noida cFunctional Nanomaterials, Institute for Materials Science, Kiel University, Kaiserstr. 2, D- 24143, Kiel, Germany

Resume : Semiconductor nanomaterials have been explored in variety of environmental applications. In this study, an attempt was made to synthesize various nanoparticles and their nanocomposites showing photocatalyst, such as CuO, ZnO and ZnO-T (ZnO-Tetrapods), and their nanocomposites i.e. CuO/ZnO and CuO/ZnO-T(ZnO-Tetrapods) by a facile and economically viable hydrothermal route. The resulting photocatalysts were characterized to determine their properties, such as morphology, band gap, crystalline structure, etc. by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), UV-Visible Absorption Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD). The potential efficacy of above photocatalysts was evaluated towards the photoremediation of Crystal Violet (CV) dye under solar light. The fast photocatalytic degradation of CV dye by pure ZnO-T could be further enhanced by hybridization with CuO due to the suppressed charge-carrier recombination. The results suggested that pure as well as nanocomposites of ZnO may be a promising candidate for waste water treatment.

Authors : Ratnesh Gupta1,*, P. Karma1, D.M. Phase2, D.K. Avasthi3, Ajay Gupta3
Affiliations : 1 School of Instrumentation, Devi Ahilya University, Khandwa road, Indore-452001, India. 2 UGC DAE CSR Indore Centre, Indore-452017, India. 3 Amity Univ., Noida, India.

Resume : Bandgap engineering and surface nano structuring of TiO2 thin films play a crucial role in increasing its efficiency to get utilized in fabrication of sensors and in optoelectronic devices [1-2]. Precise control over the defects is needed to modify the binding energy of O-2p and Ti-3d states which can bring the change in bandgap and enhance the photocatalytic activity of these thin films [3]. Ion irradiation modify the structural and electronic properties of Cr-doped TiO2 prepared by RF sputtering [2]. In the present work, we tailored the material properties by Cr-doped TiO2 prepared by pulsed laser deposition and modify its properties using swift heavy ion irradiations with different ions. The films were irradiated with 100 MeV Au and Si ion beams at different fluences ranging from 5X1012 ions/cm2 to 1X1013 ions/cm2. Structural characterization shows that as-deposited films were amorphous in nature and no phase change has been observed with increasing ion fluence rather successive amorphization of the films as confirmed by angle dispersive X-Ray diffraction technique. Field emission scanning electron microscopy images shows the agglomeration and reveals the localized defects caused by two swift heavy ions of different masses which appear as segregated clusters over the surface of thin film. Atomic Force Microscopy shows the segregation over the surface and increment in the roughness after ion irradiation. UV visible studies reveals the variation in band gap energy as the consequence of formation of various sub band-gap energy states due to accumulation of oxygen vacancies near the Fermi edge. Detailed electronic structure will be correlated with its optical properties will be discussed. References: 1. S.K.Zheng,, Vacuum 62 (2001)361. 2. Sagar Sen, Applied Surface Science 440 (2018) 403. 3. C. P. Cheney, Phys. Rev. Lett. 112 (2014) 036404.

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Metal oxides : (Session Chairs:Y. K. MISHRA, J. ADAM, M. ELBAHARI, D. K. AVASTHI)
Authors : Ashutosh Tiwari
Affiliations : University of Utah

Resume : Spintronics represents a new paradigm of electronics that utilizes both the electron’s charge as well as its spin degrees of freedom. It has the potential to facilitate a new generation of devices possessing high-speed, large memory and ultra-low power consumption. The most critical step in the functioning of a spintronic device is the injection and detection of spin-polarized carriers at the ferromagnet-semiconductor interface. Despite considerable efforts, efficient injection of spins into nonmagnetic semiconductors still continues to be a major hurdle in this field. In this talk, I will present some of our very exciting research going on in this field in my group at the University of Utah. Particular focus will be on the injection and detection of spin polarized carriers in semiconductors using electrical and thermal routes. In the later part of my talk, I will discuss about new oxide-based material systems for next-generation 2D-electronics application.

Authors : Silvio Osella, Małgorzata Kiliszek, Ersan Harputlu, Cumhur G. Unlu, Kasim Ocakoglu, Joanna Kargul, Bartosz Trzaskowski
Affiliations : Silvio Osella, Bartosz Trzaskowski, Chemical and Biological Systems Simulation Lab, Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland; Małgorzata Kiliszek, Joanna Kargul, Solar Fuels Lab, Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland; Ersan Harputlu, Advanced Technology Research & Application Centre, Mersin University, Ciftlikkoy Campus, TR33343, Yenisehir, Mersin, Turkey; Cumhur G. Unlu, Department of Biomedical Engineering, Pamukkale University, TR-20070 Denizli, Turkey; Kasim Ocakoglu, Department of Energy Systems Engineering, Mersin University, Tarsus Faculty of Technology, 33480 Mersin, Turkey.

Resume : The fabrication of highly efficient bio-organic nanoelectronic devices is still a challenge due to the difficulty in interfacing the biomolecular to the organic counterparts. One of the way to overcome this bottleneck is to add a self-assembled monolayer (SAM) in between the electrode and the biological material. The addition of a pyrene-nitrilotriacetic acid layer to a graphene metal electrode enhances the charge transfer within the device. Our theoretical calculations and electrochemical results show that the formation of the pyrene-nitrilotriacetic acid SAM enforces a direct electron transfer from SAM to graphene, while the addition of Ni2+ cation and imidazole reverses the charge transfer direction, allowing an atomic control of the electron flow, which is essential for a true working device. Moreover, the physisorption of SAM containing nitrilotriacetic acid as chelating agent strongly modify the flow of charges from and to graphene depending on the metal center used.

Authors : Erdem IRTEM (1), Jelena RADJENOVIC (1) (2)
Affiliations : (1) Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, 17003 Girona, Spain (2) Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís

Resume : Accumulation of nitrate in groundwater has been mainly attributed to agricultural activities and application of fertilizers. Excessive presence of nitrate in potable water is associated with methemoglobinemia in infants, as nitrate is converted to nitrite which binds to oxygen molecules in red blood cells. The maximum acceptable contamination level in drinking water in the EU countries is 10 mg/L for nitrate nitrogen (N-NO3-) and is endorsed by World Health Organization. Therefore, the removal of nitrate from potable and groundwater has drawn considerable attention in the water supply industry. At present, conventional water treatment plants (WTPs) cannot sustainably deliver this limit and call for implementation of advanced treatment technologies. Membrane separation processes can produce highly pure water but also give a concentrated reject solution creating a cost for its disposal. Biological denitrification can selectively convert nitrate into N2 gas, but the low reaction rate aside, biological processes cannot be applied in drinking water treatment due to the possibility of bacterial contamination of water. Catalytic chemical reduction is a promising process using metal loaded oxide supports as catalyst and hydrogen gas as the reducing agent for direct catalysis of nitrate. However, pure hydrogen gas is essential, and other disadvantages such as ammonia formation, surface rust formation and slow kinetics provide a driving force for continuing research. Electrocatalytic reduction of NO3- has been recognized as a promising alternative as it offers advantages such as elimination of pre- and post-treatment of chemicals, small footprint and relatively low investment costs with facile system control. However, energy efficiency needs improvement to reduce the operational costs. At this point, the development of stable, selective and low-cost electrodes for denitrification which can reduce nitrate (NO3-) and nitrite (NO2-) to dinitrogen (N2) is critical for sustaining the nitrogen cycle. In the scope of an ERC StG project ELECTRON4WATER, we tackle this problem via use of low-cost graphene oxide/reduced graphene oxide (GO/rGO) as catalyst electrode materials. Nanosheets of graphene oxide on glassy carbon electrode promotes the electroreduction of nitrate ions as compared with a pristine electrode (Figure 1). This also reflects to experiments with rGO modified graphite felt electrodes which were synthesized using hydrothermal method with different parameters, i.e. temperature (100 – 170 ºC) and pressure (2 – 20 kbar) to enrich its surface functionality. The results show that, the defective structure of rGO acts as active sites to induce the reduction of nitrate, and high specific surface area of the porous electrode enhanced electrocatalytic degradation of NO3-. Besides, the flow-through design of the electrochemical stack cell improves the mass transfer to reach higher reaction rates for nitrate removal. Based on the existing literature, electrochemical denitrification using flow-through stack cells and low-cost graphene based porous electrode materials has not been explored to date. A benchmark of materials synthesis parameters and its effect on the catalytic property will be highlighted. Finally, the strategies towards an innovative, next-generation water treatment technology which has the potential to create a circular nitrogen economy will be explained.

Authors : Gediminas Niaura, Agne Zdaniauskiene, Tatjana Charkova, Ilja Ignatjev, Gvidas Astromskas, Virginijus Bukauskas, Romualdas Trusovas, Rasa Pauliukaite
Affiliations : Center for Physical Sciences and Technology, Sauletekio Ave. 3, LT-10257, Vilnius, Lithuania

Resume : Electronic properties and function of graphene oxide and reduced graphene oxide depend on the surface structure, origin of defects, and adsorption of molecules at surface. To understand and control these processes, molecular level knowledge on surface structure and dynamics is required. Thus, technique specific to both interface and molecular structure must be applied. In this study, a novel surface-enhanced Raman spectroscopy (SERS) technique named “shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS)” was used to probe the nature of defects and adsorption of molecules at surfaces of graphene, graphene oxide and reduced graphene oxide. Some experiments were conducted in electrochemical cell at controlled electrode potential. SHINERS approach provides possibility to overcome important SERS limitations. The dielectric shell prevents direct interaction of probed molecules with the plasmonic metal and eliminates possible electronic effects caused by deposition of metal nanoparticles on surface. Thus, unperturbed vibrational spectroscopic information with submonolayer sensitivity might be acquired. Spectroscopic evidence for presence of perturbed aromatic rings and functional groups attached to the basal graphene plain will be discussed. Special attention will be given for analysis of electrochemical potential effect on the structure of defects and adsorption properties of aromatic molecules.

Authors : 1)Amir Hakimi Ramlan, 2)Muhammad Suffian Rosli, 3)Mohd Hanafi Ani
Affiliations : Department of Manufacturing and Materials Engineering, Kulliyah of Engineering, International Islamic University Malaysia, Malaysia,

Resume : Chemical vapor deposition of graphene is currently the most viable method in producing large- scale graphene for industrial purposes. However, due to the complexities of the process, we are yet to be able to produce graphene in large scale. This study focuses on a novel method of tailoring the quality of graphene synthesized via CVD. Here, we apply a specific amount of biased current on the substrates using a double-Langmuir probe. We postulate that this method will enable the restructuring of carbon atoms and defects thus resulting in high-quality, pristine graphene. The samples used in this study are polycrystalline Cu foils and the CVD steps proceed as per usual with heating, annealing, growth, and cooling step. In addition to these four steps, we also introduce an additional post-growth annealing treatment with temperature lower than the precedent growth temperature under stagnant Ar and H2 gas. The application of biased current proceeds separately at two steps ; 1) during the growth of graphene and 2) during post-growth annealing treatment. Raman spectroscopy is done to provide the primary graphene quality characterization. The sheet resistance of the deposited graphene is also done using a 4-point sheet resistance measurement. Lastly, a transmission electron microscopy (TEM) measurement is done to analyze the atomic structure of the graphene.

Authors : Andrea Cantelli, Matteo Di Giosia, Matteo Calvaresi
Affiliations : Alma Mater Studiorum, University of Bologna, department of Chemistry "G. Ciamician".

Resume : Versatile technological applications of fullerenes have been proposed and are in continuous development in different fields that cover lubricants, superconductors, solar cells, photocatalysis, contrast agents, and, in general, new applications for nanotechnology and nanomedicine. The insolubility of fullerene and the formation of fullerene aggregates, also in organic solvents, hampers its exploitation. The photophysical and photochemical properties of C60 depend strictly on the nature of the fullerene dispersion and a strict control of the dispersion is truly necessary for technological applications. Proteins recognize and disperse monomolecularly fullerenes. The adducts are stable in physiological and technologically-relevant environments, and easily storable. Hybridization with proteins preserves the electrochemical properties of fullerenes. Near infrared fluorimetry and EPR spin-trapping experiments show that the C60-proteins hybrids produce reactive oxygen species (ROS) following both the type I and type II mechanisms. C60 shows a significant visible light-induced generation of ROS, that can be exploited in photocatalysis or photodynamic therapy. C60-protein hybrids significantly reduced the HeLa cell viability in response to visible light irradiation. The different chemical groups offered by the protein platform allow an easy route for the functionalization of the hybrids, without altering the structure and properties of fullerene.

Authors : Xiao-lu Yan, Yu-long Wu, Bao-shun Wang, Quan Zhang, Rui-ting Zheng, Xiao-ling Wu, Guo-an Cheng*
Affiliations : Laboratory of Nanomaterial and Technology, College of Nuclear Science and Technology, Beijing Normal University, Beijing100875, China

Resume : The application of field emission (FE) devices requires emitters having a low threshold field (Eth, applied field at 10 mA/cm2) and an excellent FE stability at a high emission current density. Herein, we report on the fabrication and field emission characteristics of a carbon nanotube (CNT) emitter formed as a CNT film grown directly onnickel–chromium(Ni80Cr20)alloy wire using microwave plasma enhanced chemical vapour deposition (PECVD). The FE performance of the emitter has a low threshold field of 0.72 V/µm, a large field enhancement factor (8311.3±53.1) and an extremely large emission current density (Jmax) of 37.55 A/cm2 at a relatively low electric field of 2.13V/µm. The great increase in Jmax is ascribed to the reinforced adhesion of CNTs to the Ni80Cr20 alloy wire substrates. We believe that the direct synthesis of CNTs on the nickel–chromium wire substrate without any catalyst layers and the wrapping of the CNTrootswith a carbon nanoflake layer deposited on the surface of the wire substrate are responsible for the enhanced adhesion. Due to the strong adhesion between the CNTs and the substrate, the CNT emitter presents an excellent field emission stability at high emission current densities (14.98A/cm2), and could potentially be applied to field emission devices.

Authors : Luca Anzi, Aida Mansouri, Paolo Pedrinazzi, Erica Guerriero, Amaia Pasquera, Alba Centeno, Amaia Zurutuza, Ashkan Behnam, Enrique A Carrion, Eric Pop, Roman Sordan
Affiliations : L-NESS, Department of Physics, Politecnico di Milano; L-NESS, Department of Physics, Politecnico di Milano; L-NESS, Department of Physics, Politecnico di Milano; L-NESS, Department of Physics, Politecnico di Milano; Graphenea (Spain); Graphenea (Spain); Graphenea (Spain); Electrical & Computer Engineering, University Illinois Urbana-Champaign; Electrical Engineering, Stanford University; L-NESS, Department of Physics, Politecnico di Milano;

Resume : One of the main factors which limits performances of short-channel graphene field-effect transistors (GFETs), is contact resistance. It inhibits the use of GFETs in low-voltage applications, which is required for reducing the overall power consumption of graphene integrated circuits. We performed an extensive study on the contact resistance between graphene grown by chemical vapour deposition (CVD) and different metals. We found that etching holes in graphene below the metal contacts, strongly reduced the contact resistance reaching an exceptionally low value of 23 Ω μm in case of Au contacts. Previous studies showed that the contact resistance depends on the carrier density of graphene, i.e., it is maximum at the Dirac point and decreases by increasing the carrier density. However, we obtained the lowest contact resistance where the carrier density of graphene reaches its minimum, i.e., at the Dirac point. The application of this technology in common CVD graphene FETs, allowed us to reach an average transconductance of 940 S/m for a 500 nm channel length transistor at a drain bias of only 0.8 V, which out-perform conventional GFETs.

Authors : Oral Cenk Aktas, Muhammad Zubair Ghori, Salih Veziroglu, Bodo Henkel, Alexander Vahl, Oleksandr Polonskyi, Thomas Strunskus, Franz Faupel
Affiliations : Institute for Materials Science – Multicomponent Materials, Faculty of Engineering, Christian-Albrechts-University of Kiel, Kaiserstraße 2, 24143 Kiel, Germany

Resume : Heterogeneous photocatalysis finds more application in environmental clean-up as the water re- sources diminish enormously and the air pollution threatens the human health seriously. TiO2 is one of the most widely used photocatalytic materials for environmental remediation applications due to its low cost, chemically inertness, non-toxicity, high photocatalytic activity and recyclability. This talk will present recent activities on understanding and improvement of photocatalytic performance of TiO2 thin films. Basically main focus will be given on three main aspects: 1-Analytic approaches for determining catalytic performance, 2-Influence of UV plasmonics on the performance of TiO2 photocatalysis and 3-Functional applications of TiO2 photocatalysis: A novel method for nanostructuring.

Authors : P. Gaffuri,1,2 E. Appert,1 C. Verrier,1,3 O. Chaix-Pluchery,1 L. Rapenne,1 Q. Rafhay,3 A. Kaminski-Cachopo,3 A. Ibanez,2 M. Salaün,2 and V. Consonni.1
Affiliations : 1 Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France. 2 Univ. Grenoble Alpes, CNRS, Institut Néel, F-38042 Grenoble, France. 3 Univ. Grenoble Alpes, CNRS, Grenoble INP, IMEP-LAHC, F-38000 Grenoble, France.

Resume : ZnO nanowires (NWs) are considered as building blocks for a number of sensing, optoelectronic, and electronic devices, where the control of their electrical properties is required through intrinsic and extrinsic doping. While the doping of ZnO NWs has been performed by vapour phase deposition techniques, it is still a major issue by solution deposition techniques. In the present work, ZnO NWs are doped with different metal(III) dopants by using the low-cost, low-temperature, and easily implemented chemical bath deposition technique. Metal nitrate is basically added in various concentrations to the standard precursors [1] in deionized water. This addition completely modifies the structural morphology of ZnO NWs, as shown by electron microscopy [2]. The formation mechanisms are investigated and supported by thermodynamic simulations yielding theoretical solubility plots and speciation diagrams. Their dependence on the pH of the solution through the addition of ammonia is further studied [3]. The incorporation of metal dopants is eventually investigated by energy dispersive x-ray spectroscopy using scanning transmission electron microscopy and by temperature-dependent Raman spectroscopy, showing the occurrence of characteristic additional modes. [1] R. Parize et al., The Journal of Physical Chemistry C 120, 5242 (2016). [2] C. Verrier et al., The Journal of Physical Chemistry C 121, 3573 (2017). [3] C. Verrier et al., Inorganic Chemistry 56, 3573 (2017).

Authors : Alp KILIÇ, Onur ALEV, Serkan BÜYÜKKÖSE, Zafer Ziya ÖZTÜRK
Affiliations : Gebze Technical University Department of Physics, Kocaeli/TURKEY 41400

Resume : INTRODUCTION Nowadays, diabetes is regarded as one of the most important health problems on a global scale. Diabetes is a life-long disease that growing with insulin deficiency or ineffectiveness. In case of necessary precautions are not taken against diabetes, it causes some different eye, heart and kidney diseases and it might be fatal. The most effective method for diabetes diagnosis is blood test that has been used for many years. However, an effortless, painless and fast diagnostic method is desirable to assure patient comfort. Many breath markers or tracer compounds are accumulated and related to different diseases, either for diagnostics or monitoring. It is known that acetone presents on a certain concentration as sub-ppm (particle per million) levels in human breath is the indicator of diabetes disease [1]. For this reason, monitoring acetone level in exhaled breath for diagnosis of diabetes disease is very important issue. Semiconductor metal-oxide (MOXs) materials such as TiO2, ZnO, SnO2 and WO3 have been emphasised for use as exhaled breath analysis sensors due to their superior properties such as easy production process and reactivity against volatile organic compounds (VOCs). Several promising research efforts have been conducted for fabrication of highly sensitive exhaled breath sensors, by combining noble metals as catalyser and unique MOXs nanostructures that possess a high surface to volume ratio [2,3]. In this study, TiO2 nanorods (NRs) were synthesized via hydrothermal process. Then, noble metals such as Ag (silver), Pd (palladium), Pt (platinum) were loaded on the TiO2 NRs via magnetron sputtering or thermal evaporation techniques for exhaled breath analysis. Finally, sensor tests were performed at low concentrations of different breath markers such as acetone, ethanol, HCN (hydrogen cyanide). MATERIALS and METHODS TiO2 NRs were synthesized via hydrothermal method on Al2O3 (alumina) substrate. A solution that is consist of titanium (IV) n-butoxide, hydrochloric acid and deionized water mixture was used for hydrothermal process [4]. Then, catalytic metals (Ag, Pd, Pt, etc.) were deposited with magnetron sputtering or thermal evaporation methods. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction spectroscopy (XRD) methods were used to characterize the morphology and crystal phase of fabricated samples. For gas sensor measurements, Au interdigital electrodes (IDEs) were thermally evaporated on top of the sample surface. The fabricated sensor devices were exposed to acetone, ethanol and HCN for the concentrations ranging between 128 and 4 ppm at different operating temperature between 50 and 300oC. RESULTS and DISCUSSIONS SEM images show that TiO2 NRs homogenously cover entire alumina surface. NRs are tetragonal in shape and they have an average diameter of 250 nm. XRD spectra demonstrated that TiO2 NRs arrays have crystallized in a rutile phase. Sensor measurements were performed at varying temperatures and concentrations to understand loading effect on sensor properties. According to sensor measurements, functionalised TiO2 NRs with Ag catalyst shows clear response toward 4 ppm acetone. Metal catalysts on TiO2 NRs show different catalytic characteristics, thus specify sensor properties such as sensor response, sensitivity, selectivity and optimal operation temperature. ACKNOWLEDGEMENTS This study is financially supported by Scientific and Technological Council of Turkey (TUBITAK) project number 116M201. REFERENCES [1] Marco Righettoni et al., Materials Today 18 3 (2015) 163-171. [2] Erdem Şennik et al., Sensors and Actuators B, 199 (2014), 424–432. [3] Seon-Jin Choi et al., Analytical Chemistry, 85 (2013), 1792-1796. [4] Onur ALEV et al., Procedia Engineering 120 (2015) 1162-1165.

Authors : Y. Bourlier 1,2, M. Frégnaux 1, B. Bérini 2, M. Bouttemy 1, A. Fouchet 3, D. Aureau 1, Y. Dumont 2
Affiliations : 1 Institut Lavoisier de Versailles (UMR 8180), Université de Versailles Saint-Quentin-en-Yvelines - CNRS - Université Paris-Saclay, 45 Avenue des Etats-Unis 78035 Versailles, France ; 2 Groupe d’Etude de la Matière Condensée (UMR 8635), Université de Versailles Saint-Quentin-en-Yvelines - CNRS - Université Paris-Saclay, 45 Avenue des Etats-Unis 78035 Versailles, France ; 3 CRISMAT, CNRS UMR6508, ENSICAEN, Normandie Université, 14050 Caen Cedex 4, France.

Resume : The use of perovskite oxide materials assembled into thin film heterostructures appears promising for future prospects in the field of oxitronics. However, due to technological constraints, these materials cannot compete yet with other technologies for integration and device processing. Indeed, effective heterostructures require high quality materials, stable over time, whose morphology and roughness are well-controlled. SrVO3 (SVO) is a remarkable material because it presents a metal–insulator transition (MIT). It is also a great candidate for transparent conductive oxide. In this context, Pulsed Laser Deposition (PLD) technique is a good technique to grow complex ternary oxide with an efficient cationic transfer of target. Nevertheless, some parameters as laser fluency, repetition rate, temperature and O2 partial pressure in the deposition chamber are able to strongly modify the obtained materials. Influence of the oxygen pressure has been studied previously. Layers with differences in terms of morphology and physico-chemical properties have been obtained. We were able to form Sr3V2O8 nanostructures on SVO thin films or to obtain flat surfaces. A fine physico-chemical study and an accurate chemical environment determination by XPS, Auger nano-probe of conductive oxide SVO ultra-thin layers is presented, in relation with this morphology and structure by AFM and STEM, and discussed. This will allow a better integration of SVO in a “all oxide” integrated electronics.

Authors : Yeliz Unutulmazsoy, Claudia Cancellieri, Lars P.H. Jeurgens
Affiliations : Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf CH-8600, Switzerland

Resume : A comprehensive understanding of the oxidation behavior of thin Cu films is an issue of a fundamental interest and particularly relevant for applications in the fields of microelectron-ics, sensors, catalysis and solar cells. The current study reports on the oxidation kinetics and phase formation evolution (Cu2O to CuO) upon heating of magnetron sputtered Cu (111) films in a temperature range of 100 to 450 °C as a function of oxygen partial pressure. In-situ resistance measurements were performed to follow oxide growth rate of Cu films (20 to 150 nm) to Cu2O films in a temperature range of 100 - 300 °C in air. It is found that the oxidation kinetics of Cu films follows the linear rate law, which indicates that oxygen dissociation at the surface is rate-limiting process in this temperature range. As shown by XRD investiga-tions (both in the laboratory and the synchrotron), the oxide phase formation critically de-pends on the oxidation conditions. Cu2O is the major oxide phase at 300 °C at 1 bar in air, whereas CuO becomes dominant at 400 °C for oxidation of 150 nm thick Cu films. The in-situ real-time synchrotron XRD measurements, as conducted at 400 °C (for 50 nm) and 450 °C (for 150 nm) at 1-10 mbar, reveal that the formation of CuO only starts after complete ox-idation of the Cu thin films to Cu2O.

Authors : A.V. Kondakova(1), M.V. Gorbachevsky(2), G.A. Kuralbayeva(3), A.A. Eliseev(1), S. Jana(4), A.N. Vasiliev(1,3,5), V.Yu. Timoshenko(1,6,7)
Affiliations : (1) Lomonosov Moscow State University, Moscow, 119991, Russia; (2) Gubkin Russian State University of Oil and Gas, Moscow, 119991, Russia; (3) National University of Science and Technology ?MISIS?, Moscow, 119991, Russia; (4) S. N. Bose National Centre for Basic Sciences, Kolkata, 700106, India; (5) National Research South Ural State University, Chelyabinsk 454080, Russia; (6) National Research Nuclear University ?MEPhI?, Moscow, 115409, Russia; (7) Lebedev Physical Institute of the Russian Academy of Sciences, 119991 Moscow, Russia

Resume : Halloysite nanotubes (HNTs) with surface-immobilized silver (Ag) nanoparticles (NPs) were explored as nano-templates for surface-enhanced Raman scattering (SERS). The structure and plasmonic properties of NHTs/Ag NPs nanocomposite during storage in water was checked by means of the transmission electron microscopy and optical absorption spectroscopy, respectively. A remarkable SERS response for tested dye molecules of R6G was observed for fresh HNTs/Ag NPs and the SERS activity decreased by several times for the samples stored in water for one week. The observed SERS-activity is explained by desired morphology of Ag NP distribution on the surface of HNTs, which was only slightly modified during storage in aqueous medium. The revealed stability of the SERS activity of NHTs/Ag NPs nanocomposites seems to be promising for their application in biosensorics. The work was supported by the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST "MISIS" (No. K2-2017-084) implemented by a governmental decree dated 16 March 2013, No. 211.

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Energy and Photocatalysis : (Session Chairs:Y. K. MISHRA, L. POLAVARAPU, J. ADAM, M. ELBAHARI)
Authors : Xuanhua Li
Affiliations : School of Materials Science and Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi’an, China, 710072

Resume : The design of advanced transition-metal chalcogenides (TMCs) photocatalysts for water splitting is highly important, in which both light absorption and interfacial engineering play vital roles in exciton generation, separation, electron transport, and ultimately speeding up water splitting. To this end, plasmonic metal nanomaterials with surface plasmon resonances are promising candidates. However, it is very difficult to enhance the light absorption and manage the interfacial engineering simultaneously, thus, resulting in suboptimal photocatalytic performance. Here, a nonmetal plasmon is proposed to optically and electrically enhance TMCs hydrogen evolution. With the tunability of plasmon resonance in a MoO3 semiconductor via hydrogen reduction, the broadband absorption and good interfacial engineering have simultaneously been demonstrated in flexible MoS2@MoO3 core-shell nanowire photocatalysts. Better energy-band alignment with MoS2 can also be realized, thereby achieving improved photoinduced exciton separation in the hybrid structure. More importantly, the defects at the interface between MoO3 and MoS2 are effectively reduced because of precise tunability of nonmetal plasmon resonance, which enhances electron transport. As a proof of concept, this optimized hybrid nanostructure exhibits outstanding H2 evolution characteristics (841.4 μmol h-1 g-1) that is 6.73 times of the pure MoS2, excellent stability, and good flexibility. The value is also one of the highest hydrogen evolution activity rate to date among the 2D layered visible light photocatalysts. This work opens a new direction to simultaneously improve the light-absorption characteristics and achieve efficient electron transport in the photocatalytic water-splitting reaction.

Authors : Aadesh P. Singh, Björn Wickman, Anders Hellman
Affiliations : Division of Chemical Physics, Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden

Resume : Conversion of solar energy to chemical fuel in a photoelectrochemical (PEC) devices requires an inexpensive and stable semiconductor photoelectrode materials with explicit control over the three main requirements in a single material system: 1) chemical stability 2) visible light absorption and 3) band edges matching to redox levels of water. This talk will summarize the results obtained for photoelectrochemical water splitting using metal oxide semiconductor such as BiVO4, TiO2 and α-Fe2O3. Our attention has been devoted to further modify these oxide semiconductors by using various strategies like band edge engineering, material disordering, nano/micro engineering, surface/interface engineering to improve the performances of metal oxide-based materials, especially favoring the photoelectrochemical activity under simulated sunlight. Recently, a new engineering strategy, i.e., band re-alignment at the heterostructure was achieved by gas–phase modification technique which strongly promotes interfacial interaction at the junction and leads to an effective interfacial charge separation and transport. The modified α-Fe2O3/TiO2 heterostructures exhibit significant enhancement of visible light absorption and improve the photoelectrochemical response.

Authors : Sandeep Kumar and Ashok K Ganguli
Affiliations : Indian Institute of Technology Delhi India

Resume : Abstract An outstanding challenge in the realm of photocatalysis is the development of functional nanomaterials in the visible region of the electromagnetic spectrum. We have investigated the tunability of electronic and optical properties of semiconductor nanostructures by control of their shape, size and also the mechanism of growth of anisotropic nanostructures1 which have applications in water splitting, photocatalysis and photovoltaics. Coupling of wide band gap semiconductor such as ZnO, NaNbO3, SnO2 with narrow band gap semiconductors like Ag2S, In2S3, CuInS2 etc. (which acts as sensitizer) forms efficient heterostructures (core/shell) for the separation of photogenerated charge carriers and makes it a good candidate for visible-light photocatalysis. The enhancement in photocatalytic activity also elaborate is due to the efficient photoinduced interfacial charge transfer (IFCT) mechanism.2,3 The spatial electron-hole separation between the core and shell, is greatly enhanced by the type-II band alignment between core/shell heterostructures, results in the extremely long exciton lifetime.4 In the aim of society to move towards a clean environment5 and availability of sufficient energy, hydrogen is the key to both these challenges. Tremendous interest exists on hydrogen generation from electrochemical or photoelectrochemical water splitting. Hydrogen having highest energy density per unit mass is eco-friendly as it produces only water after combustion as a direct fuel or after transformation to electricity in fuel cells. Among earth abundant non-noble metals, molybdenum-based materials are important for hydrogen evolution reaction because of low cost, good conductivity and catalytic efficiency. The interfacial charge transfer at various heterojunctions such as core/shell, composite and doped nanomaterials is important for energy conversions. Current research of our group is focused on 2D materials, metal oxides, metal chalcogenides and alloy nanostructures for photoelectrochemical water splitting, photocatalytic organic pollutant (dye) degradation, photocatalytic fuel generation and water purification. References 1. Kumar, S.; Parthasarathy, R.; Singh, A. P.; Wickman, B.; Thirumal, M.; Ganguli A. K. Dominant {100} Facet Selectivity for Enhanced Photocatalytic Activity of NaNbO3 in NaNbO3/CdS core/shell heterostructures, Catal. Sci. Tech., 2017, 7, 481-495. 2. Kumar, S.; Ojha, K.; Ganguli, A. K. Interfacial Charge Transfer in Photoelectrochemical Processes, Advanced Materials Interfaces, 2017, DOI: 10.1002/admi.201600981. 3. Kumar, S.; Singh, A. P.; Bera, C.; Thirumal, M.; Mehta, B. R.; Ganguli, A. K. Visible Light Driven Photoelectrochemical and Photocatalytic Performance of NaNbO3/Ag2S Core/Shell Heterostructure, ChemSusChem, 2016, 9, 1850–1858. 4. Kumar, S.; Singh, A. P; Yadav, N.; Thirumal, M.; Mehta, B. R. Ganguli, A. K. Fabrication of TiO2/CdS/Ag2S Nano-Heterostructured Photoanode for Enhancing Photoelectrochemical and Photocatalytic Activity under Visible Light, Chemistry Select, 2016, 1, 4891–4900. 5. Sunita Khanchandani, Sandeep Kumar, and Ashok K. Ganguli: Comparative Study of TiO2/CuS Core/Shell and Composite Nanostructures for Efficient Visible Light Photocatalysis ACS Sustainable Chem. Eng.2016, 4, 1487−1499.

Authors : Tomáš Halenkovič, Jan Gutwirth, Virginie Nazabal, Petr Němec
Affiliations : Department of Graphic Arts and Photophysics, Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice, Czech Republic; Department of Graphic Arts and Photophysics, Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice, Czech Republic; Laboratoire Verres et Céramiques , Institut des sciences chimiques de Rennes, UMR CNRS 6226, Université de Rennes 1, 35042 Rennes, France; Department of Graphic Arts and Photophysics, Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice, Czech Republic

Resume : Recently, amorphous chalcogenides from ternary Ge-Sb-Se system have grabbed the attention in the field of nonlinear optics due to its high refractive index and wide transmission window in the mid-IR region. Fabrication and studies of amorphous thin films are of great importance for both general research of various properties and applications in the form of slab waveguides. GeSe2, GeSe4, Sb2Se3 and Ge28Sb12Se60 sputtering targets were used for extensive research of optical properties of Ge-Sb-Se thin films fabricated by co-sputtering technique. Variable angle spectroscopic ellipsometry was used for the determination of optical bandgap (Eg) and linear refractive index (n). Third-order nonlinear optical susceptibility (χ(3)) and non-linear refractive index (n2) were extracted from dispersion characteristics. Furthermore, morphological and topographical properties of fabricated films were studied by scanning electron microscopy and atomic force microscopy, respectively. Suitability of amorphous chalcogenides as a novel nonlinear materials for photonics is discussed.

Authors : Salih Veziroglu, Muhammad Zubair Ghori, Katharina Roder, Thomas Strunskus, Franz Faupel, Oral Cenk Aktas,
Affiliations : Institute for Materials Science, Christian Albrechts University, 24143 Kiel, Germany

Resume : Titanium (IV) oxide (TiO2) is a commonly used as a photocatalyst because of its availability, chemical/physical stability, non-toxicity and low-cost. However, the low quantum efficiency and the wide bandgap (3.0-3.2 eV) of TiO2 limit its use in photocatalytic applications. Moreover, the high rate of charge recombination of photo-generated electron/hole pairs dramatically decreases the photocatalytic efficiency of TiO2. Several studies have reported that plasmonic metal nanoparticles (NPs), such as gold (Au) and silver (Ag), and improve the photocatalytic performance of TiO2 and extend the electron/hole pairs lifetime by trapping electrons 1. In such studies mostly Ag NPs are preferred to modify TiO2 because of silver’s low-cost, excellent conductivity, chemical stability and near-field enhancement. Although various methods are available for the deposition of Ag NPs on TiO2 surfaces, controlling the size of the Ag NPs at the nano-scale and depositing a uniform distribution without any NP agglomeration are challenging 2. In this study, we deposited uniform Ag NPs on TiO2 thin films by photocatalytic deposition over different time intervals (from 1 min to 5 min). Detailed structural and compositional analyses of prepared samples were performed by SEM, TEM and XPS. Additionally, UV-Vis spectroscopy was used to measure the photocatalytic activity of prepared samples. Under UV irradiation, Ag NP-decorated TiO2 thin films exhibited enhanced photocatalytic performance compared to bare TiO2 thin films. The results indicate that photo-generated electrons are trapped due to the strong electron accepting ability of Ag NPs (deposited in <1 min), resulting in an effective separation of electron/hole pairs. However, excessive Ag NPs (deposited in >1 min) on TiO2 not only act as electron/hole recombination centers but also partially shade TiO2 surface from UV irradiation. 1. Clavero, C. Plasmon-induced hot-electron generation at nanoparticle/metal-oxide interfaces for photovoltaic and photocatalytic devices. Nat. Photonics 8, 95–103 (2014). 2. Barhoum, A., Rehan, M., Rahier, H., Bechelany, M. & Van Assche, G. Seed-Mediated Hot-Injection Synthesis of Tiny Ag Nanocrystals on Nanoscale Solid Supports and Reaction Mechanism. ACS Appl. Mater. Interfaces 8, 10551–10561 (2016).

Authors : Emmanuel Nyankson*#, Vasant R. Kumar*
Affiliations : *Department of Materials Science and Metallurgy, University of Cambridge, UK # Department of Materials Science and Engineering, University of Ghana, Ghana

Resume : Semiconductor based photocatalysts have been examined for their potential in solving many environmental and energy problems. Developing highly efficient visible light active photocatalyst has therefore become the focus of most researchers. A highly efficient Ag-Ag3PO4 photocatalyst was synthesized by including formaldehyde in the precipitation synthesis of Ag3PO4. The as-synthesized Ag-Ag3PO4 was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS). The Ag-Ag3PO4 photocatalyst shows an increase of over 300 % in rate of photocatalytic rhodamine blue dye degradation compared to Ag3PO4 under visible light illumination. Heat treatment of the as synthesized Ag-Ag3PO4 almost doubled its pseudo first order rate constant for the degradation of rhodamine blue dye. The synthesized photocatalyst was stable after cycles of photocatalytic degradation of rhodamine blue dye. The photocatalytic activity enhancement can be attributed to the good electron trapping role of Ag nanoparticles deposited on the surface of the Ag3PO4.The potential application of the Ag-Ag3PO4 in oil spill remediation will be examined through photocatalytic degradation of aromatic and aliphatic components in crude oil. The rate of degradation of the aromatic components will be compared with that of the aliphatic components. The intermediate components generated will also be reported.

Authors : Stefan Gärtner(1,2), Felix Manger(1,2), Philipp Meier(1,2), Manuel Koppitz(1,2), Konstantin Glaser(1,2) and Alexander Colsmann(1,2)
Affiliations : (1) Light Technology Institute, Karlsruhe Institute of Technology (KIT), Engesserstrasse 13, 76131 Karlsruhe, Germany (2) Material Research Center for Energy Systems (MZE), Karlsruhe Institute of Technology (KIT), Strasse am Forum 7, 76131 Karlsruhe, Germany

Resume : The industrial fabrication of organic solar cells is often hampered by toxic solvents that require strong safety precautions. Whereas the use of chlorinated solvents or toxic hydrocarbons is feasible in the lab, their use in large scale printing processes would lead to enormous operational costs, which conflicts with the goal of cost effective production. In this work, we present efficient organic solar cells that were fabricated from non-toxic and eco-friendly organic nanoparticle dispersions. In an inverted solar cell architecture with a nanoparticulate P3HT:ICBA layer, the power conversion efficiency of 5% nearly matches the performance of reference devices that were fabricated from dichlorobenzene. We further demonstrate that this device fabrication concept is well suited for upscaling. To understand the origin of the high performance of these surfactant-free nanoparticulate organic solar cells, we performed small angle neutron scattering (SANS) and transient absorption spectroscopy (TAS) on precipitated P3HT:ICBA nanoparticles. In contrast to the well-known core-shell morphology of miniemulsion-nanoparticles, we found the nanoparticles formed by surfactant free precipitation were homogenous, that is, the donor and acceptor were evenly distributed in the nanoparticle. We find that the bulk-heterojunction is already prearranged within the nanoparticles, allowing for assembly of nanoparticulate layers with optimal morphologies, with thermal annealing leading to merging of nanoparticle interfaces to facilitate charge extraction.

Sensing and Biomedical : (Session Chairs:Y. K. MISHRA, L. POLAVARAPU, J. ADAM, M. ELBAHARI)
Authors : Utkarsh Jain*, Nidhi Chauhan, Sukirti Tiwari, Asmita Gupta
Affiliations : Amity Institute of Nanotechnology, Amity University, Sector 125, Noida, Uttar Pradesh

Resume : Acetylcholine (ACh) is a neurotransmitter found in the autonomic ganglia and the neuromuscular junction. Synthesis of ACh takes place in nerve terminals from acetyl coenzyme A and choline. This reaction is catalysed by choline acetyltransferase (CAT). Altered levels of Ach are associated with dementia, hallucinations, memory loss and Alzheimer’s disease. In the present work, Multi-walled Carbon Nanotubes- Manganese oxide nanoparticles (MWCNT-MnO2 NPs) are utilized for the amperometric detection of ACh. Nanoparticles and their composites impart various advantageous characteristics than their bulk counterparts. MnO2 NPs are important functional metal oxide, as it is attributed with unique chemical and physical properties along with low cost and less toxicity, environmental compatibility. Due to these properties they can be utilized in applications, such as, ion exchange, catalysis, biosensor, and energy storage particularly, molecular adsorption. MWCNT is widely utilized as a supporting material due to their excellent properties such as high surface area, electrical and thermal conductivity and chemical stability. Due to larger surface area, they can be used as effective templates to deposit the MnO2-NPs on the surface with high stability. In order to further enhance the electrochemical efficiency of the system, the MWCNT-MnO2 is deposited on the surface of reduced graphene oxide (rGO).

Authors : T. Haffner [a], F. Bassani [a], P. Gentile [b], A. Gassenq [b], N. Pauc [b], E. Martinez [c], S. David [a], T. Baron [a], E. Robin [d], B. Salem [a]
Affiliations : [a] Univ. Grenoble Alpes, CNRS, LTM, 38000 Grenoble, France ; [b] Univ. Grenoble Alpes, CEA, INAC-Pheliqs, 38000 Grenoble, France ; [c] Univ. Grenoble Alpes, CEA, LETI-DTSI, 38000 Grenoble, France ; [d] Univ. Grenoble Alpes, CEA, INAC-MEM, 38000 Grenoble, France

Resume : Germanium-Tin (GeSn) alloy, a low-bandgap group-IV material, has attracted growing attention in recent years for its potential integration in microelectronic and optoelectronic devices. It is expected a high carrier mobility and an indirect to direct bandgap transition for Sn concentration as low as 8% [1]. However, the low solubility (<1%) of Sn in Ge and their large lattice mismatch (≈15%) are real challenges to be overcome for the epitaxy of high-crystalline quality GeSn alloy. Several research groups have shown the possibility to elaborate 2D GeSn thin films on Si using chemical vapor deposition (CVD) [2] or molecular beam epitaxy (MBE). These approaches offer a good control for the tin incorporation and the possibility to create heterostructures with sharp interfaces. However, the large lattice mismatch between GeSn and Si (>4.2%) [3] leads to a high density of misfit dislocations during the growth of 2D thin film, hindering the alloy crystalline quality. Direct growth of NWs via the vapor liquid solid (VLS) mechanism offers a full strain relaxation, and thus, a high crystalline quality. In this work, we have investigated the CVD-VLS direct growth of GeSn nanowires and Ge/GeSn core-shell structures. GeH4 and SnCl4 are used as germanium and tin precursors, respectively. A flow of HCl was maintained in the chamber during the process in order to limit the 2D uncatalyzed growth along the nanowires. Au colloids of calibrated diameter of 50 nm and 100 nm were used as catalysts. The nanowires morphology and growth rate were investigated as a function of the growth temperature and the partial pressure ratio of precursors by SEM. Nano-auger and STEM-EDX analysis reveal the existence of a thin Sn rich shell (> 10%) [4]. Core-shell NWs exhibit a variety of {112} and {110} facets with different tin composition. The non-homogenous distribution of Sn in these NWs will be discussed. [1] D. Stange et al, ACS Photonics, vol. 2, no. 11, pp. 1539–1545, 2015. [2] J. Aubin et al, ECS J. Solid State Sci. Technol., vol. 6, no. 1, pp. P21–P26, 2017. [3] H. S. Mączko et al, Sci. Rep., vol. 6, no. 1, p. 34082, 2016. [4] T. Haffner et al, Phys. status solidi, vol. 215, no. 1, p. 1700743, 2018.

Authors : V. Yu. Timoshenko(1,2,3), Yu.V. Kargina(1,2), T. Yu. Bazylenko (1,2), A. F. Alykova(2), M. V. Gulyaev(1), S.V. Savilov(1), A.M. Perepukhov(4), S.M. Zinoviev(2,5), E. A. Zvereva(1), A. A. Maximychev(4), Yu. A. Pirogov(1), J. Beckman(6), N.V. Sharonova(7), V.P. Zubov(7), A.A. Ischenko(7)
Affiliations : (1) Lomonosov Moscow State University, 119991 Moscow, Russia; (2) National Research Nuclear University “MEPhI”, Phys-Bio Institute, 115409 Moscow, Russia; (3) Lebedev Physical Institute of the Russian Academy of Sciences, 119991 Moscow, Russia; (4) Moscow Institute of Physics and Technology, Dolgoprudny, 141700 Moscow Region, Russia; (5) Blokhin National Medical Research Center of Oncology, 115478 Moscow, Russia; (6) Therapon, Inc., Springdale, Arkansas, U.S.A.; (7) Russian Technological University - MIREA, Institute of Fine Chemical Technologies named after M.V. Lomonosov, 119454 Moscow, Russia

Resume : Silicon nanoparticles (Si NPs) with sizes 10-100 nm were prepared from Si microcrystalline powder by arc-discharge plasma-assisted ablative synthesis. The structure and physical properties of Si NPs were investigated by means of the transmission electron microscopy, spectroscopy of Raman scattering and photoluminescence, as well as by electron paramagnetic resonance technique. Aqueous suspensions of Si NPs were examined as contrast agents (CA) for magnetic resonance imaging (MRI). Both the transverse relaxation time and longitudinal one for protons in water were found to decrease strongly in aqueous suspensions of Si NPs due to a high concentration of the paramagnetic centers in the latter. The corresponding transverse proton relaxivity was comparable with commercially available CAs. Aqueous suspensions of Si NPs at concentration above 0.1 g/L exhibit noticeable contrast enhancement for T2-weighted MRI. In-vivo MRI visualization of mice with grafted malignant tumor and introtumorally administrated Si-NPs indicate a significant potential of the latter NPs as potential CAs for MRI diagnosis and therapy of cancer.

Authors : Ashish Mathur
Affiliations : Amity Institute of Nanotechnology, Amity University, Noida, 201301, (UP), India

Resume : Hectic lifestyle in the modern world demands a rapid, accurate and reliable early diagnosis of “Heart Attack” (acute myocardial infarction). Our primary objective is to develop a cost-effective, rapid and label-free point of care diagnostic test kit for detection of cardiac marker (troponin-I) based on paper-based multi-frequency impedimetric transducers. Paper based sensing platforms were developed by integrating carboxyl group functionalized multi-walled carbon nanotubes (MWCNT’s) with anti-cTnI biomarker. The MWCNT’s/anti-cTnI modified micro-paper based analytical device (µPAD) was characterized using Electrochemical Impedance Spectroscopy (EIS). Various concentrations of cardiac troponin I (cTnI) with anti-cTnI were studied as a function of impedance change. The suitability of the proposed µPAD immunosensor is demonstrated with spiking of cTnI in blood serum samples. The limit of detection of the proposed sensor was found out to be 0.05 ng/mL, with response time of < 1 min. The rapid response, very low detection limit, and cost effectiveness makes the proposed immunosensor a potential platform to screen the presence of cTnI in blood serum samples. The proposed immunosensor can, therefore, offers an affordable healthcare system in resource limited areas.

Authors : Souradeep Roy (1), Shalini. N (1), Shikha Wadhwa (1), Nidhi Chauhan (1), Utkarsh Jain (1), Ashish Mathur (1) and James Davis (2).
Affiliations : (1) Amity Institute of Nanotechnology, Amity University, Noida, 201313, India. (2)NIBEC, Ulster University, Jordanstown Campus, Northern Ireland, BT370QB, UK

Resume : The lifetime risk of people with diabetes to develop a foot ulcer is 34%. More than 50% of diabetic foot ulcers (DFUs) become infected, in which case, the patient may need to undergo amputation. L-tyrosine is an amino acid, the concentration of which is found to be highly elevated in patients suffering from DFUs. Therefore out of 20 standard amino acids present in wound fluid, we have chosen L-tyrosine as the potential bio-marker (analyte to be detected). The highly expensive and time consuming conventional diagnostic protocols demand the development of micro/nano-fluidic point-of-care (POC) sensors for early and real time monitoring of DFUs. Various transducer-surfaces, based on numerous nanomaterials, have been reported for bio-sensing out of which molecular imprinted polymer (MIP) is well known for specific target-binding which yields high sensitivity and detection limit. In this work, an electrochemical sensor based on molecular imprinted poly-pyrrole (MIPPy) has been synthesized on ITO electrodes (2 cm x 1 cm) using L-Tyrosine as the template. The thin film of poly-pyrrole was electro-deposited on an electrode area of 1 cm2. The electrochemical response of imprinted polymers has been extensively studied, using cyclic voltammetry and impedance spectroscopy, by varying the concentration of tyrosine from 1 µM ? 1 fM. The MIPPy based sensor displayed detection limits in the order of femto-molar along with response time of about 5 seconds.

Authors : Rizwan Wahab1, Farheen Khan2, Yogendra Kumar Mishra3, Abdulaziz A.Al-Khedhairy1
Affiliations : 1Zoology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; 2Department of Chemistry, Taibah University, Yanbu, Madinah, Saudi Arabia; 3Functional Nanomaterials, Institute for Materials Science, University of Kiel, Kaiser Str. 2, 24143, Kiel, Germany

Resume : The metal oxide quantum dots (QDs), which are having a special place in the family of nanoscience and nanotechnology because of their very small dimension ~2-10 nm, having about 10-50 atoms in diameter. These unique material exhibit larger surface area of the crystals, highest valence and lowest conduction band and releases more energy, when the crystal returns to its resting state. Although, QDs are having various applications in electronic such as solar cells, LED, UV illuminator, screen televisions, has property to glow particular color after being illuminated by light. Very limited informations are available to use of QDs as a nanomedicine. Due to their very small size, it provides various advantages and can be possible to enter in any types of biological identities/targets such as cells and microbes etc. The studies demonstrated the use of QDs as nanomedicine and were check their efficacy against myoblast cancer cells. Various studies were performed such as MTT assay was used to know the % viability of cells in presence of different concentration of QDs, incubation period (24, 48, and 72 h), cells morphology, intrinsic effect etc. The Real Time PCR, which is the back bone to know the genetic studies, was used to check the apoptosis in cells with different genes at different incubation time. Including this, the study was also authenticated with different analytical parameters such as limit of quantitation, detection, recovery, relative standard deviation, which is highly affected and significant analysis under the different doses of QDs with cells. On the basis of acquired studies and their observations, the possible mechanism was also presented.

Authors : S. Sajed, F. Arefi, M. Kolahdouz, M. Neshat, M. Sadeghi, S. F. Mirahmadi*
Affiliations : University of Tehran, North Karegar Str., Eng Faculty, ECE department, Tehran, Iran * Presenting author

Resume : Detection of drinking water contaminations such as heavy metal ions and toxic chemicals is costly, time-consuming and requires an accompanying computing device to capture and analyze the data. Therefore, there is an extensive need for rapid, user-friendly, cost-effective, portable and ubiquitous detection technique. Utilizing smartphone is an effective way to measure, analyze and send the results. Here, we quantify mercury and lead in water samples with an excellent level of sensitivity. The designed device is a 3D printed structure which can be attached to any smartphone and is integrated with optical components. Gold nanoparticle and aptamer based colorimetric sensor are utilized to determine concentration of Hg2 and Pb2 . Interaction between aptamer and the analytes leads to a color change in the solution due to aggregation of gold nanoparticles. Optical sources used in the system are light-emitting diodes (LEDs) at 450, 523 and 625 nm and a dedicated App on smartphone to communicate, receive and analyze data. The proposed method offered a detection limit in ppb range for the mentioned ions. This approach provides an instrument for accurate, rapid and in situ control of water safety with no need of technical expertise. This platform on the smartphone has the benefit of improving sensing, cloud storage, sharing information and online data management.

Luminescence and Optics : (Session Chairs:Y. K. MISHRA, L. POLAVARAPU, J. ADAM, M. ELBAHARI, D. K. AVASTHI)
Authors : S. Núñez-Sánchez, S. Rodal-Cedeira, J. Juste-Pérez, I. Pastoriza-Santos
Affiliations : Departamento de Química Física and CINBIO, Universidade de Vigo, 36310 Vigo, Spain

Resume : Since Jelley and Scheibe discovered J-Aggregates (J-A) in 1937, scientists and engineers are studying how to control and exploit the properties of these supramolecular structures in photonic technologies. Their intriguing properties such as spontaneous and reversible self-assembly, dramatically strong molar absorbance, narrow absorption bands or insensitivity to the environment combined with their coherent exciton transport along molecular chains makes them an extraordinary nanophotonic building block. In this talk I will explain two different approaches to exploit these supramolecular dyes as building blocks for photonic applications. Firstly, I will explain how densely doped J-A polymer films can establish a novel molecular route for nanophotonics. These densely packed J-A thin films exhibit inherent metal-like properties making them able to confine the field at nanoscale similar to plasmonic metals. As metals were the motor of plasmonics, molecular materials can guide us to establish the parameters for a fully plastic excitonic nanophotonics. Secondly I will go further in the application of J-As in photonics combining them with plasmonic nanoparticles (NPs). Hybrid plexcitonic NPs were prepared by the combination of Au NPS with J-A. Their optical properties evidence the achievement of strong coupling regime between plasmonic NPs and molecules. We will analyze the advantages of these plexcitonic NPS and their potential use as robust SERS tags in the strong coupling regime.

Authors : Søren Peder Madsen, Joakim Vester-Petersen, Rasmus E. Christiansen, Ole Sigmund, Adnan Nazir, Peter Balling, Brian Julsgaard
Affiliations : Department Of Engineering, Aarhus University; Department Of Engineering, Aarhus University; Department Of Mechanical Engineering, Danish Technical University; Department Of Mechanical Engineering, Danish Technical University; Interdisciplinary Nanoscience Center, Aarhus University; Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University; Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University;

Resume : The efficiency of Si solar cells can be raised by converting two low energy photons into one photon with energy above the Si band gap, which then adds to the current production in the Si cell. This is not efficient at natural sunlight intensities, and the light therefore needs to be focused to enhance the non-linear upconversion process. Metal nanostrips and nanoparticles on top of an erbium-doped TiO2 upconverting thin film can be used to focus the part of the incoming light that matches the absorption band of erbium into the thin film. The focusing efficiency depend on the geometry of the metal nanoparticles and gradient-based topology optimization is used to efficiently calculate optimized designs. Topology optimization allows for almost unlimited freedom in the design and several techniques are used to make the design production-friendly with respect to electron beam lithography. Physically, the optimization process can exploit scattering, plasmonic, and waveguiding as well as diffraction effects for periodic arrays. Designs utilizing the latter tend to show very good performance but are also extremely sensitive with respect to changes, e.g. in wavelength and angle of incidence. Topology optimization can find non-trivial designs which are efficient and, at the same time, not so sensitive to variations in wavelength, angle of incidence, and particle geometry.

Authors : Sung-gyu Kang, Euijoon Yoon, Heungnam Han, In-Suk Choi
Affiliations : Department of Materials Science and Engineering, Seoul National University

Resume : In the present study, we set out to show that α-alumina hollow nanoshell structure can exhibit an ultrahigh fracture strength even though it contains a significant number of nanopores. By systematically performing insitu mechanical testing and finite element simulations, the high fracture strength of an α-alumina hollow nanoshell structure can be explained in terms of conventional fracture mechanics even at the nanoscales. More importantly, by deriving a fundamental understanding, we would be able to lay down predictions and guidelines for the design of reliable ceramic nanostructures for advanced GaN LEDs. To that end, we demonstrated how our ultra-strong α-alumina hollow nanoshell structures could be successfully incorporated into GaN LEDs, thereby greatly improving the luminous efficiency and output power of the LEDs.

Authors : Alexander S. Urban
Affiliations : Ludwig-Maximilians-Universität München Department for Physics Nanospectroscopy Group

Resume : Halide perovskite nanocrystals are prepared via several synthetic routes to obtain dimension-controlled nanocubes, nanoplatelets or nanowires. We investigate the effect of size and dimensionality on the optical and electronic properties of the nanocrystals, focusing on quantum-confinement and carrier dynamics. With binding energies of up to 300 meV, 2D nanoplatelets exhibit many properties reminiscent of epitaxially grown quantum wells but at room temperature. However, due to their unique geometry and organic ligand surrounding, they exhibit vastly different carrier relaxation dynamics, with a strong dependence on the thickness of the samples. These nanoplatelets are shown to be excellent emitters in the blue spectral region, where perovskite nanocrystals typically perform poorly. Inorganic Cs-based nanocubes, which have previously displayed extremely high quantum yields, are used as precursors to create larger structures. We explore the energetic and electronic coupling between the NCs and explore the resulting optical properties, especially for lasing applications.

New Materials : (Session Chairs:Y. K. MISHRA, L. POLAVARAPU, J. ADAM, M. ELBAHARI, D. K. AVASTHI)
Authors : Xuemei Han
Affiliations : Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University

Resume : Liquid marbles are quasi-spherical or puddle-like structures which efficiently isolate microdroplets in a non-stick shell formed spontaneously via coating of solid particles onto the liquid surface.1 Using functional particles as the encapsulating layers, the application of liquid marble has been further broadened. Here, we demonstrate liquid marble as microreactor, microsensing, and even micromanipulation platform for triggering, radiating, and even monitoring reactions in enclosed environment. We firstly fabricate plasmonic liquid marble to form 3D multilayer SERS-active shell, allowing rapid and molecular-level sensing of enclosed contents of liquids.2 We unravel reaction mechanism and kinetics using the experimental time-dependent SERS spectra and DFT simulation. Such microreactor system can be further utilized as unit to develop microchemical factory for automatically mixing reactants, monitoring reaction, and sensing product.3 We also utilize magnetic nanoparticles to fabricate liquid marble, exhibiting superior spinning behaviour when floating on water surface.4 Such dynamic and highly controlled spinning behaviour is benefit for microcentrifudge and microsensing platform for liquid surface viscosity. Moreover, taking advantage of the centrifugal force created during liquid marble rotation, we investigate the centrifugal force driven chemical reaction kinetics control.5 Overall, the ensemble benefits offered by functional liquid marbles create enormous opportunities in the development of multifunctional microreactor for versatile applications.

Authors : S. Goswami, T. Venkatesan
Affiliations : NUS Nanoscience and Nanotechnology Institute

Resume : Handling of big data necessitates the need for disruptive innovations in computing devices. The new generation of devices should be able to process high data density at the cost of low energy. At the moment, devices meeting both these criteria are rare and demand a quantum leap from the state-of-the-art systems. Here we report resistive memory devices based on a spin-coated active layer of a transition metal complex, which shows high reproducibility (~350 devices), fast switching (<30 ns), excellent endurance (~10^12 cycles), stability (>10^6 s) and scalability (down to < 60nm^2). In devices with an active area of ~ 60nm^2, we are able to demonstrate switching energy on the order of 100aJ (4 orders better than the next best report), where the local-field enhancement on the nano-sized electrodes facilitate the switching. In-situ Raman and ultraviolet-visible spectroscopy alongside spectroelectrochemistry and quantum chemical calculations demonstrate that the redox state of the ligands determines the switching states of the device whereas the counterions control the hysteresis [1,2]. Based on this insight, we are able to further engineer our molecules to realize a ternary memory device where two of the conductance plateaus are formed due to different molecular redox states, while the third one arises from charge disproportionation (CD) and formation of supramolecular dipoles, characterized by an enhanced dielectric constant. The realization of a voltage-controlled, disorder driven CD state at room temperature is mechanistically unprecedented and suggests a new route to tailor a wide range of reconfigurable optical as well as electronic multi-state devices. Having realized these functionalities with a metal-organic complex, we resolve the long-standing problems of organic electronics including poor reproducibility, fragility, low speed, and poor scalability making them a potential candidate for wearable and flexible electronics which are becoming integral parts of emerging technologies like the internet of things (IoT) and artificial intelligence (AI). [1] Goswami, Sreetosh, et al. "Robust resistive memory devices using solution-processable metal-coordinated azo aromatics." Nature Materials 16.12 (2017), 1216. [2] Valov, Ilia, and Michael Kozicki. "Non-volatile memories: Organic memristors come of age." Nature Materials 16.12 (2017), 1170.

Authors : Santosh KC , Valentino R. Cooper
Affiliations : Oak Ridge National Lab, USA

Resume : The hallmark of many nanomaterials is that the interlayer or interparticle distances are often close to the size of the particle itself. At these length scales, noncovalent (van der Waals) forces are paramount. They drive several phenomena with far reaching real world implications in electronics, sensors, batteries, fuel cells, carbon capture and many more. Originating from correlated electron fluctuations, they require an electronic structure solution. I will discuss efforts predicting atomic and magnetic structure of layered 2D materials and illuminating the importance of van der Waals interaction. Emphasis will be on accurate first-principles solutions for describing nanoscale materials properties derived from van der Waals interactions. I will show how it helped in understanding the spin-lattice coupling in magnetic layered materials as well. I will demonstrate how the inclusion of these forces is essential to their fundamental understanding; thus, being crucial to the computational design of functional nanomaterials.

Authors : K. Shportko1*, L. Revutska2, J. Baran3, A. Stronski1, and E. Venger1.
Affiliations : 1 V. Lashkaryov Institute of Semiconductor Physics of NAS of Ukraine, Kyiv, Ukraine; 2 National Technical University of Ukraine “Ihor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine. 3 W. Trzebiatowski Institute of Low Temperatures and Structure Research of PAS, Wroclaw, Poland;

Resume : Chalcogenides are very promising materials for using in optoelectronics as high-speed optical elements, for applications such as data processing devices, electronic switches and optical elements. Phase-change chalcogenides being already employed in the optical data storages are among the most promising functional materials for new generations of multilevel data storage and data visualization applications. These applications employ the property contrast between amorphous and the crystalline states. In the present study, we report our results on the Urbach-Martienssen tails in the IR spectra of amorphous AsxSy and (GeTe)x(Sb2Te3)1-x chalcogenides. This study is aimed to reveal the compositional dependences of optical properties of studied alloys. We have also tried to deduce whether the absorption edge fluctuations associated with structural disordering have influence on the absorption process through the compositional dependences of the bandgap energy Eg and the Urbach energy Eu.

Authors : Kannikka behl1, Mahima Sharma2, Monika Joshi2, Devesh Kumar Awasthi2, Amit Bhatnagar3, Subhasha Nigam1*
Affiliations : 1Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, India, 201313. 2Amity Institute of Nanotechnology, Amity University, Noida, Uttar Pradesh, India 201313. 3Department of Environmental and Biological Sciences, University of Eastern Finland, P.O.Box 1627, FI70211, Kuopio, Finland.

Resume : Microbial Fuel Cell (MFC) is a sustainable energy transducer, that directly coverts organic matter into electrical energy. The present work demonstrates the MFC to be promising for wastewater treatment and bio-energy production. A bio film of photosynthetic green alga Chlamydomonas sp. TRC-1 deposited on fluorine doped tin oxide (FTO) electrodes was investigated for its ability to generate power. Cyclic voltammetry (CV) scans recorded, sharp anodic and cathodic peak with a potential difference ∆V= 0.239 V. A peak power output of 10.02 mW/m2 was observed with a current density of 27A/m2. The algal biofilm applied in MFC improved the physicochemical parameters of the wastewater, significantly reducing the chemical oxygen demand (COD: 77.1%), total dissolved solids (TDS: 82.1%) and total suspended solids (TSS: 87.4%). The study not only offers an economically and eco-friendly solution to successful power generation but also contributes towards waste water treatment and biofuel production.

Authors : Z. Fazlali, E. Hosseininejad, A. Fazelian, M. Kolahdouz, M. Neshat, J. Poursafar*
Affiliations : School of Electrical and Computer Engineering, University of Tehran, Tehran, Iran * Presenting author

Resume : Conventional electronics, which is based on rigid substrates, cannot respond to the requirements of new generation of applications such as wearable electronics or bio-implanted systems. In today?s information oriented world, there are many applications such as medicine, aeronautic, entertainment and RFID that the antenna needs to be bended, rolled and potentially folded. Having the merits of light weight, low profile, low manufacturing cost, decreased fabrication complexity in addition to easy access to inexpensive substrates are the main causes for the increasing demand of flexible and wearable electronics. In this paper, a monopole antenna operating over dual band of 900 MHz and 2.4 GHz for conformal wireless application is proposed and simulated. We used silver nanoparticle ink and Epson inkjet printer to print the designed antenna on a 150 µm transparent and flexible polyethyleneterephthalate (PET) substrate. To measure the antenna, we used Agilent vector network analyzer (VNA). We achieved return loss of -14 dB at 900 MHz and -22 dB at 2.4 GHz that were matched with the simulation results. In simulation results, we reached the gain of 1.96 dBi and 2.77 dBi for 900 MHz and 2.4 GHz, respectively and 10.9? and 20.78? bandwidth for 900 MHz and 2.4 GHz, respectively. We also tested antenna in bending situations to characterize its performance in realistic setups. The results showed that the proposed antenna works properly in curved situations.


Symposium organizers
Devesh Kumar AVASTHIUniversity of Petroleum and Energy Studies (UPES)

Department of Physics, School of Engineering - Energy acres, 248007, Dehradun, India
Jost ADAM (Main Organizer)University of Kassel

Computational Materials and Photonics (CMP), FB 16 - Wilhelmshöher Allee 71, D-34121 Kassel, Germany
Lakshminarayana POLAVARAPUCINBIO, Universidade de Vigo

Materials Chemistry and Physics Group, Department of Physical Chemistry, Campus Universitario Lagoas, Marcosende, 36310 Vigo, Spain
Mady ELBAHRIAalto University

School of Chemical Technology, Kemistintie 1, C321, 00076 Aalto, Finland
Yogendra Kumar MISHRA (Main organizer)Mads Clausen Institute, University of Southern Denmark

Alsion 2, 6400, Sønderborg, Denmark