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Hybrid, organic and bio-materials

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Molecular materials - towards quantum properties (MOLMAT-Q)

Molecular Materials attract growing interest in science and technology due to its (i) cutting-edge basic research projects targeting physics within the quantum regime (e.g. molecular spintronics, nuclear spin manipulation) and (ii) applied research leading to new applications and devices close to market introduction (e.g. optoelectronics). This session takes place as part of the series of conferences “Molecular Materials” (MOLMAT).

Scope:

Molecular Systems whose structures and components, due to their inherent nanoscale size, exhibit unusual or enhanced properties partially uniquely expressed in the quantum regime. The processing and manipulation of the quantum properties of molecular materials as well as the fabrication of devices with new sustainable approaches are crucial issues towards a technology based on intelligent materials in Europe. Molecular Materials are foreseen to have a pervasive impact on industry, economy and many aspects of society, including our everyday life.

This symposium is aimed at providing a forum where the quickly growing community of scientists and researchers working on functional molecular nanosystems based on magnetic and photophysical materials, and more in general, how Molecular Materials achieve an impact in nanoscience and nanotechnology.

A particular emphasis is given to the bottom-up approach since the ability to manipulate the local nanoscopic environment is crucial to access fundamentally new classes of physical effects in the nanoregime showing unprecedented properties and performance. In fact, despite the progress of the last ten years in the area of molecular spintronics and photophysics much remains to be done to achieve coherent control at the nanoscale.

This symposium will bring together experts in the fields of fundamental physics, synthetic chemistry, material science, as well as device engineering.

Obtaining such cross-over knowledge is also crucial from an applicative point of view, and therefore for society. This is first of all a consequence of the connection between the development of organic electronics and molecular spintronics, which are about to be applied in first consumer electronics devices. In the longer term, it can be reasonably envisioned that ongoing research may address quantum logics and computation based of the inherent quantum character of molecules.

Hot topics to be covered by the symposium:

  • Surface-confined synthesis of Novel Materials
  • Molecular Magnetic Materials • Spintronic Materials
  • 2D Graphenoids
  • Light Emitting Devices (LEDs, LETs, LECs)
  • Fundamental issues on organic materials properties at the nanoscale
  • Design and synthesis of dynamic supramolecular nanostructured materials
  • p- conjugated (macro)molecules
  • Electroactive and photoactive supramolecular architectures
  • Self-assembly and self-organization
  • Hybrid nanostructured multifunctional architectures
  • Molecular mechanics and dynamic simulation of supramolecular arrangements
  • Molecular Quantum Materials
  • Nanofabrication
  • Bottom-up nanopatterning
  • Nanoscale tools and nanomanipulation
  • Scanning Probe Microscopies
  • Nanooptics and fast spectroscopy of functional materials
  • Optical properties of organic interfaces
  • Local properties of spatially confined nano-objects
  • Charge injection and transport in hybrid metal - supramolecular architectures
  • Organic solar cells
  • Nanoelectronics: Organic Thin Film Transistors and supramolecular nanowires
  • Supramolecular switches and motors
  • Quantum Information Processing and Quantum Computation

List of invited speakers:

  • Albert Fert (Thales-Lab Paris, France, Nobel Laureate in Physics 2007)
  • Karl Leo (IAPP Dresden, Germany)
  • Paul Blom (Max-Planck-Institute for Polymers, Mainz, Germany)
  • Marco Affronte (Modena University, Italy)
  • Herre van der Zant (TU Delft, The Netherlands)
  • Richard Winpenny (Manchester University, UK)
  • Luis Hueso (NanoGUNE, San Sebastian, Spain)
  • Wolfgang Wernsdorfer (Institute Néel, Grenoble, France)
  • Eugenio Coronado (Valencia University, Spain)
  • Franc Meyer (Göttingen University, Germany)
  • Roberta Sessoli (Florence University, Italy)

International Advisory Board:

  • Jean-Pierre Sauvage (Strasbourg)
  • Bernard Barbara (Grenoble)
  • Günther Reiter (Freiburg)
  • Jose-Ramon Galan-Mascaros (Taragona)
  • Marcel Mayor (Basel)
  • André-Jean Attias (Paris)

Publication:

Papers will be published in Beilstein Journal of Nanotechnology.

Symposium organizers:

Mario Ruben
Karlsruhe Institute of Technology
INT-KIT, PF 3640
D-76021 Karlsruhe
Germany
Tel: +49 (0)724 7826781
mario.ruben@kit.edu
www.ruben-group.de
or
IPCMS- CNRS-UMR 7504
Université de Strasbourg
23, Rue du Loess, BP.43
F-67034 Strasbourg cedex 2
France

Azzedine Bousseksou
CNRS, Laboratoire de Chimie de Coordination, UPR8241
205, route de Narbonne
F-31077 Toulouse cedex 04
France
Phone: +33 (0)5 61 33 31 69
Fax: +33 (0)5 61 55 30 03
boussek@lcc-toulouse.fr

Guillem Aromi
Universitat de Barcelona
Departament de Química Inorgànica
Diagonal, 645
08028 Barcelona
Spain
Phone: +34 93 403 9760
guillem.aromi@qi.ub.es

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Quantum properties of integrated Carbon based nanomaterials : Mario Ruben
09:15
Authors : M. Affronte, A. Candini, V. Corradini, V. Bellini.
Affiliations : CNR Institut Nano S3 Modena and University of Modena

Resume : Hybrids made of carbon based nanomaterials and molecular nanomagnets (MNM) represent a viable route for quantum spintronics: magnetic molecules can be used as elementary units with well defined quantum features while graphene and CNT are excellent templates to make electronic devices and interconnects at the nano-scale. Prototypical hybrids mimicking spintronics devices have been recently realized [1]. Yet, in order to fully exploit their novel quantum features we need to control the interplay between MNM and graphene. Here I?ll focus on the interaction between mononuclear (bis-)phtalocianine and graphene. More specifically, I?ll discuss the case of FePc and LnPc_2 (Ln=Tb, Dy, Er) on graphene grown on Ni(111) surface by presenting our recent low temperature XAS and XMCD investigations. When molecules are deposited directly on Ni(111) surface we observe an exchange coupling of the magnetic centre with the Ni substrate. We firstly evaluate the interplay between this exchange and the single atom anisotropy in different cases including the cases of paramagnetic Fe, axial anisotropy (Tb) and in-plane anisotropy (Er). This exchange coupling is weakened by the insertion of graphene between the molecules and the Ni(111) surface. These results are interpreted by DFT calculations that account for different configurations of local bonds. [1]Graphene Spintronic Devices with Molecular Nanomagnets. A. Candini, S. Klyatskaya, M. Ruben, W. Wernsdorfer and M. Affronte Nanoletters 11, 2634?2639 (2011)

M.M.I..1
10:00
Authors : P. Du, D. Kreher, F. Mathevet, F. Charra, T. Pick, B. Helms, A.-J. Attias
Affiliations : Université Pierre et Marie Curie, Paris, France; CEA Saclay, France; LBNL, Berkeley, USA

Resume : One of the critical challenges in the field of two-dimensional (2D) supramolecular self-assemblies at surfaces is: how to exploit the room above the substrate, to provide to the physisorbed adlayer potential functionalities in view in view of solving scientific problems and applications in nanoscience? This is why we developed the Janus tecton concept. This is a versatile molecular platform based on the design of three-dimensional (3D) building blocks consisting of two faces linked by a pillar: one face is designed to steer 2D self-assembly on sp2 carbon flat surfaces, the other one exposes the desired functionality (either a chemical or functional unit) above the substrate. Scanning tunneling microscopy and molecular mechanics calculations show effectively that we offer a generic platform exposing a functionality in the third dimension with a well-controlled lateral order, paving the way for the noncovalent functionalization of sp2-carbon materials, opening interesting perspectives for applications in nanoscience as we will demonstrate in this presentation. Moreover, the successful self-assembly on graphene, together with the possibility to transfer the graphene monolayer onto various substrates, considerably expends the domains of application of our functionalization strategy,

M.M.I..3
 
Opto-electronic molecular materials : Nuria Crivillers
11:00
Authors : R. Brueckner, M. Sudzius, A.A. Zakhidov, A. Mischok, V. Lyssenko, R. Scholz, H. Froeb, and K. Leo*
Affiliations : Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden, Germany *:also: King Abdulllah University of Science and Technology, Saudi Arabia

Resume : Organic microcavities offer fascinating opportunities to study the interactions of light and organic matter. These observations are made possible by the large oscillator strengths and exciton binding energies provided by organic semiconductors. For electrically driven devices, highly conductive electrodes have to be integrated. For this purpose metallic electrodes are under study, but the large absorption properties of metals are generally to prevent optical coherence. In this talk, we will focus on the impact of metallic structures implemented into organic microcavities. Optimizing the structural design and introducing a higher order confinement are beneficial to maintain optical coherence at low thresholds. First, a homogeneous silver layer of 40nm thickness is implemented into a high quality organic microcavity. By exciting this structure non-resonantly the transition from a single photonic cavity mode to two coupled Tamm states is observed Optimizing the design reduces the overall optical losses and increases the Q factor to 650 allowing for the observation of coherent emission from cavity photons and Tamm plasmons at room temperature. Furthermore, lateral confinement of the optical modes can be introduced by generating an optical gain grating or by structuring the metal layer by means of photo-lithography. Structuring the metal layer into periodically placed stripes leads to the observation of surface plasmon polaritons and Bloch-like photonic bands. Above the lasing threshold, macroscopic coherence on different Bloch states is observed.

M.M.II..1
11:30
Authors : Umberto Giovanella(1), Giuseppe Leone(1), Francesco Galeotti(1), Fabio Bertini(1), Sajjad Hoseinkhani(1), William Porzio(1), Giovanni Ricci(1), Wojciech Mróz(1), Francesco Meinardi(2), Chiara Botta(1)
Affiliations : (1) CNR, Istituto per lo Studio delle Macromolecole (ISMAC), via E. Bassini 15, 20133 Milano, Italy (2) Dipartimento di Scienze dei Materiali, Università di Milano-Bicocca, via Cozzi 55, 20125 Milano, Italy

Resume : A facile and robust approach for fabricating structured, blue-emitting polymer hybrids is explored by grafting poly(styrene) incorporating π-conjugated terfluorene side-chains, to fluoromica silicate layers through surface-initiated nitroxide-mediated polymerization [1]. The hybrids exhibit blue photoluminescence quantum yield as high as 0.90 in the solid, and significantly enhanced thermal and chemical stabilities with respect to the organic precursors. The successful assessment of the hybrid material as efficient emitter in a light-emitting device is accomplished, and we shed light onto the not straightforward mechanism responsible for its emission. The layered hybrid approach allows us to achieve, at the same time, planarization and chemical and photo- stability of short oligo(fluorene)s whose emissive properties are enhanced thanks to exciton localization. Lying-flat intercalated terfluorene moieties are sensitized by non planar conformers grafted onto the outer polymer chains, that envelop the silicates, through a resonant energy transfer mechanism. Single layer solution processable device displays deep blue electroluminescence with an external quantum efficiency of 1.2 %, maximum luminance close to 1000 cd/m2, chromaticity coordinates of (0.16;0.11) and low efficiency roll-off thanks to the separation of the emissive region from the charge transport one. [1] Leone et al. J. Mater. Chem. C, 2013, 1, 6585

M.M.II..2
11:45
Authors : Cheong Shin, Won-Kook Choi and Jeon-Kook Lee
Affiliations : Interface Control Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea

Resume : Quantum dots (QDs) are uniquely suited for use as lumophores in light emitting devices for large-area planar lighting. We use the inorganic semiconductors as a charge transport layers and demonstrate devices with light emission. The low luminescence was attributed to luminescence quenching of the QDs in conductive electrodes, QD charging, and the imbalance in the polarity of charges injected into the device. Mechanically smooth films were chosen to prevent electrical shorts between the semiconductor and the QDs. We grow semiconducting oxide films with low free-carrier concentrations to minimize the quenching of the QD EL. The hole transport layer (HTL) and the electron transport layer (ETL) having similar carrier concentrations and energy-band offsets to the QDs were used because the electron and the hole injection into the QD layer should be balanced. Metal oxides offer a deposition-dependent morphologies and conductivities. For the ETL and the HTL, we selected a 40-nm-thck ZnO:SnO2(ZTO) and InGaZnOx(IGZO) with a resistivity of 10 cm. To improve the emission intensities, we observed the effects of the spin coating parameters and the concentrations of QD colloidal solutions. As the spin coating speeds were decreased from 2,000 to 500 rounds per minute (rpm), QD layer uniformities were improved. To reduce the morphologically induced electrical shorts in the device, we control the deposition parameters of ZTO or IGZO sputtering. We deposit transport layer onto the ZnSe:ZnS QDs layers formed on the transport layers. We use the Indium Tin Oxide (ITO) electrode on the glass substrate. Adhesion between the QDs layers and the ZTO layer was improved by using the molecular linker, 2-carboylehtylphosphonic acid (CAPO).We demonstrate the role of the QDs concentration on the luminescence properties. Our devices were measured without environmental packaging and in atmospheric conditions. We obtain the bright and uniform pixel at 10V applied bias. Light emitting uniformity was improved by reducing the rpm of QD spin coating. In the case of QD concentration of 15 mg/mL, we observe the bright electroluminescence at 12V applied bias. Much of the decrease in QD luminescence can be attributed to additional quenching by the free carriers in the ETL.

M.M.II..3
 
Molecular Functions : Jose Sanchez Costa
14:00
Authors : R. Sessoli,a M.-E. Boulona, M. Manninia, L. Pogginia, A. Caneschia, A. Rogalev b, F. Wilhelm b, A. Vindigni,a M. Scarrozza,d P. Barone,d S. Picozzi,d
Affiliations : a Dip.to di Chimica ‘Ugo Schiff’, Università degli Studi di Firenze & INSTM RU, 50019 Sesto Fiorentino, Italy. b European Synchrotron Radiation Facility, 38000 Grenoble, France c Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich, Switzerland d Consiglio Nazionale delle Ricerche CNR-SPIN, 67100 L’Aquila, Italy

Resume : Chiral magnetic structures have been recently the focus of intense research because they offer the possibility to store information in topological protected structures like skyrmions. Chirality and magnetism are also directly connected in the interaction between matter and electromagnetic radiation through the magneto-chiral dichroism and birefringence. Magneto-chiral dischroism (MCD), a non-reciprocal effect with different absorption of unpolarized light by systems with opposite chirality in the presence of a magnetic field, is a fascinating phenomenon that has been suggested to be at the origin of homochirality of life on the earth and observed only recently. It is in general very weak, being assumed in first approximation to be related to the product of natural (NCD) and magnetic circular (MCD) dichroism, and only few examples are available in literature with limited information on the factors that originate the phenomenon. We report here a detailed synchrotron investigation of the magneto-chiral effect detected at the 3d-metal K edge in two isostructural molecular helices comprising either isotropic Manganese(II) or anisotropic Cobalt(II) bridged by stable organic radicals. The experiments have revealed a strong magneto-chiral dichroism associated with the non-collinear spin structure of the CoII derivative, which is also the archetype of Single-Chain Magnets, i.e. one-dimensional structures showing magnetic bistability due to short-range magnetic correlation. Interestingly, the chiral nature of these molecular helices allows the presence of novel magneto-electric effects. Density Functional Theory calculations have in fact revealed that the electric polarization of the molecular helix is affected by the relative alignment of neighbouring metal and radical spins, opening the perspective of controlling the magnetization dynamics of these one-dimensional structures through the application of an electric field. The authors acknowledge the financial support of the European Research Council through the AdG MolNanoMaS and of Italian MIUR through FIRB project n° RBAP117RWN.

M.M.III..1
15:00
Authors : Oleg V. Kolosov, Peter D. Tovee, Manuel Pumarol, Nicholas D. Kay, Benjamin J. Robinson
Affiliations : Physics Department, Lancaster University, Lancaster, LA1 4YB, UK www.nano-science.com

Resume : Two-dimensional (2D) materials such as graphene, MoS2, Bi2Se3 possess outstanding electrical, thermal, and mechanical properties. While electronic or optical properties are the main focus of research, their nanoscale mechanical and thermal properties of these materials are extremely important for the fundamental understanding and applications of these 2D nanostructures. We use a combination of scanning probe microscopies that combines low frequency and ultrasonic vibrations to map a wide dynamic range of stiffnesses from 0.02 to 2000 N/m with the lateral resolution of few nanometres. That allowed us to investigate results of residual stresses in supported graphene layers that revealed themselves as broken mechanical contact at the interface between graphene layer and the substrate, as well as to explore nanomechanical behaviour of few layer suspended graphene, MoS2 and Bi2Se3 films. We directly observed the transition of graphene layer deformation from plate to stretched membrane behaviour, and created nanoscale maps of shell instability for few layer graphene sheets, providing insight to the stresses in the free standing graphene films. We also addressed the challenge of exploration of thermal phenomena in graphene nanostructures by scanning thermal microscopy in high vacuum environment that allowed us to directly map thermal transport in suspended and suppored graphene layers with nanoscale resolution, and to explore both ballistic and diffusive regimes of heat transfer.

M.M.III..4
16:30
Authors : Mateusz Janeta, Łukasz John*, Sławomir Szafert
Affiliations : University of Wrocław, Faculty of Chemistry, Joliot-Curie 14, Wrocław 50-383, Poland mateusz.janeta@chem.uni.wroc.pl

Resume : Polyhedral oligomeric silsesquioxanes (POSS) are organosilicon compounds with the empirical chemical formula RSiO3/2. Their three dimensionality, high symmetry, and nanometer size make them promising building blocks for nanomaterials. Combining the robust core with the functionalities of the attached organic groups can also change the physical properties of the POSS. A route to a large variety of functionalized POSS compounds by a two-step procedure has been developed. In the first step, an aminofunctionalized alkoxo silane such as 3-aminopropyltriethoxy silane is converted to amino-functionalized POSS (amine-POSS) by a sol–gel process. In the second step, the amine groups of amine-POSS are converted by state-of-the-art amine chemistry. A large number of reactants, including acids halides, esters, anhydrides or acrylates as well as reactants suitable for nucleophilic substitution can be applied. Conversion of an amine-POSS with acids halides leads to an amide-POSS. Amine chemistry can usually be performed under mild conditions, which suppresses degradation and/or cross-linking reactions of the amine-POSS during the conversion. Here we report syntheses and characterization of a new amido-POSS with alkyl and aryl groups. ESI-TOF mass spectrometry and nuclear magnetic resonance spectroscopy (1H, 13C, 29Si, and correlation spectroscopy) have been applied to prove the conversion of an amine-POSS to an amide-POSS.

M.M.PI..5
16:30
Authors : Vigile Trannoy,a Giulia Fornasieri,a Marco Faustini,b David Grosso,b Anne Bleuzen.a
Affiliations : a Institut de Chimie Moleculaire et des Materiaux d'Orsay-UMR 8182, Equipe de Chimie Inorganique, Universite Paris-Sud 11, 91405 Orsay Cedex (France) b Laboratoire de Chimie de la Matiere Condensee de Paris, Universite Pierre et Marie Curie-Paris 6 and CNRS, College de France, 11 place Berthelot 75231 Paris (France)

Resume : Research on smaller and more powerful devices for data storage involves the design of new materials at the nanoscale. Our aim is to develop magnetic nanoparticles with high magnetic anisotropy (oxides or alloys) localized in well-organized nanocraters of a non-magnetic thin film.[1-2] Prussian blue analogues (PBA) were chosen as precursors of the magnetic particles owing to their particularly well-defined structure and chemical composition combined to their versatile chemistry. By tuning PBA chemistry, it should be possible to tune the chemical composition, the structure and therefore the magnetic properties of the derived oxides and alloys. The nanoperforated oxyde thin films were performed using sol-gel chemistry in addition with surfactant micelle templating. PBA growth into the nanocraters has been made layer by layer after a functionalization of the surfaces. The thermal treatment under controlled atmospheres allows the transformation of PBA into oxides or alloys. [3-4] Here we present our first results on the thermal treatment under oxidizing and reductive atmospheres of Co4[Fe(CN)]2.7 PBA confined into the nanocraters of nanoperforated TiO2 thin film. [1] S. Lepoutre, D. Grosso, C. Sanchez, G. Fornasieri, E. Riviere, A. Bleuzen, Advanced Materials 22 (2010) 3992. [2] J. Allouche, D. Lantiat, M. Kuemmel, M. Faustini, C. Laberty, C. Chaneac, E. Tronc, C. Boissiere, L. Nicole, C. Sanchez, D. Grosso, J. Sol-Gel Sci. Technol. 53 (2010) 551. [3] M. Yamada, M. Maesaka, M. Kurihara, M. Sakamoto, M. Miyake, Chem. Commun. 2005) 4851. [4] R. Zboril, L. Machala, M. Mashlan, V. Sharma, Crystal Growth & Design 4 (2004) 1317.

M.M.PI..6
16:30
Authors : C. Kaulen (1), M. Homberger (1), N. Babajani (2), S. Karthäuser (2), U. Simon (1)
Affiliations : (1) Institute of Inorganic Chemistry (IAC) and JARA-FIT, RWTH Aachen University, Germany; (2) Peter Grünberg Institut (PGI-7) and JARA-FIT, Forschungszentrum Jülich GmbH, Germany

Resume : Integration of molecule-capped gold nanoparticles (AuNP) into nanoelectronic devices requires (i) adjustable electrical resistance of the capping molecules, (ii) a reliable contact of the capping molecules to the electrode material[1] and (iii) immobilization of a defined number AuNP into electrode structures. In order to accomplish the latter we investigated the adsorption characteristics of 1,8-mercaptooctanoic acid and 8-amino-1-octanethiol stabilized AuNP (12.3±1.1 nm) on gold/palladium and platinum surfaces. Here, we present how AuNP differentially adsorb to the respective metals, directed by pH, ionic strength, and the composition of the electrolyte chosen[2]. In summary, AuNP with acidic end groups adsorb exclusively on platinum at pH 9 but on gold/palladium at pH 5. AuNP with amine end groups adsorb preferentially on platinum at pH 3. With these findings the integration of single, molecule capped AuNP and even the directed immobilization in nanoelectronic devices gets feasible. [1] S. Karthäuser, J. Phys. Cond. Mat. 23, 013001 (2011) [2] C. Kaulen et al., Langmuir (2014) dx.doi.org/10.1021/la404110y

M.M.PI..12
16:30
Authors : Hyo Jung Kim1, Ji Whan Kim2, Junhyuk Jang3, and Jang-Joo Kim3, Hyun Hwi Lee4,*
Affiliations : 1Pusan National University, Korea;2Samsung Advanced Institute of Technology, Korea;3Seoul National University, Korea;4Pohang Accelerator Lab., Korea;

Resume : The Effect of surface energy on the nano-grain structures of ultra thin copper(II) phthalocyanine (CuPc) films was investigated and their thermal evolution was also analysed by real time grazing incidence small angle X-ray scattering (GI-SAXS) and X-ray reflectivity measurements On hydrophilic Si surface, CuPc film consisted of disk shaped nano-grains of two different sizes. The larger grains showed lateral crystal growth and planarization by thermal annealing, while the smaller grains did not increase in size. The grains formed clusters at high temperature. On hydrophobic Si surface, CuPc nano-grains are more randomly distributed. The crystal size did not increase in size upon thermal annealing. Thermal annealing induced a more random distribution of nano-grains with an increase in roughness, and large islands formed by the coalescence of small grains. The different thermal evolution models of CuPc films based on GI-SAXS analysis are consistent with the different temperature behavior of the hole mobilities of organic field-effect transistor (OFET) devices fabricated on both surfaces. References [1] H. J. Kim, J. W. Kim, H. H. Lee, T.-M. Kim, J.-J. Kim, The Journal of Physical Chemistry Letters 2, 1710 (2011). [2] H. J. Kim, H. H. Lee, J. W. Kim, J. Jang, and J.-J. Kim, Journal of Materials Chemistry 22, 8881 (2012).

M.M.PI..13
16:30
Authors : Bitam Said 1, Abdelbaki Djebaili 2
Affiliations : 1 Laboratory of Physical chemistry L.P.C - University of Média- Algeria 2 Laboratory of chemistry and environmental chemistry L.C.C.E - University of Batna- Algeria

Resume : Investigation of the geometric and electronic structure of the polyacetylene with substituent’s of different strengths of donor and acceptor functional groups was carried out with 3-21G basis sets, by incorporating The rates of this geometrical isomerization and Arrhenius parameters. In the case of unsubstituted polyacetylene as the reference.. The values of the equilibrium constant for the reaction have also been determined at various temperatures between 300 and 500 K and the value of the energies change calculated. The results demonstrate that the isomerization energies are positive and the barrier heights ∆Ebarrier are expected to be sensitive for the magnitude of substituents effects.

M.M.PI..17
16:30
Authors : Srikanth Chakaravarthy 1,2, Alain Bulou 2, Mauricio Ortega Lopez 3, Jaime Santoyo Salazar 4
Affiliations : 1 Programa de Doctorado en Nanociencias y Nanotecnología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), No. 2508 Av. IPN, Col. San Pedro Zacatenco, C.P. 07360 Distrito Federal, México 2 l'Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, Université du Maine, 72085 Le Mans Cedex 9 France 3 Sección de Electronica y Estado Solido, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), No. 2508 Av. IPN, Col. San Pedro Zacatenco, C.P. 07360 Distrito Federal, México 4 Departmento de Fisica, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), No. 2508 Av. IPN, Col. San Pedro Zacatenco, C.P. 07360 Distrito Federal, México

Resume : This work reports the colloidal synthesis of silver telluride (Ag2Te) nanoparticles by adapting a predefined procedure. As synthesized materials were rinsed several times with deionized water and anhydrous ethanol, and preserved in toluene. All the characterizations were performed on the drop-casts inks on suitable substrate. The crystallinity and phase group were assessed by x-ray diffraction (XRD) technique. Field emission scanning electron microscope (FESEM-EDX) analyses reveal nearly stoichiometric composition and self-assembled nature of the nanocrystals. Size, shape, crystallinity and dispersity were studied by high resolution transmission electron microscopy (HRTEM), which reveals that the nanoparticles are of nearly spherical and cubicle in morphology and in the size range of 5-10 nm resulted in different batches. Results will be discussed in detail.

M.M.PI..21
16:30
Authors : Srikanth Chakaravarthy 1,2, Alain Bulou 2, Mauricio Ortega Lopez 3, Jaime Santoyo Salazar 4, Marie-Pierre Crosnier Lopez 2
Affiliations : 1 Programa de Doctorado en Nanociencias y Nanotecnología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), No. 2508 Av. IPN, Col. San Pedro Zacatenco, C.P. 07360 Distrito Federal, México 2 l'Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, Université du Maine, 72085 Le Mans Cedex 9 France 3 Sección de Electronica y Estado Solido, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), No. 2508 Av. IPN, Col. San Pedro Zacatenco, C.P. 07360 Distrito Federal, México 4 Departmento de Fisica, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), No. 2508 Av. IPN, Col. San Pedro Zacatenco, C.P. 07360 Distrito Federal, México

Resume : Colloidal synthesis of lead telluride nanocrystals have been carried out by adapting a predefined procedure. The crystallinity and phase group were assessed by x- ray diffraction (XRD) technique. Qualitative analyses of the sample were performed using Raman spectroscopy. The interaction between oleic acid and PbTe nanocrystals are analyzed by subjecting the samples to Fourier transform infrared spectrometry. Field emission scanning electron microscopic analyses reveal lead rich stoichiometric composition and self-assembled nature of the nanocrystals both on silicon substrate as well as on carbon tape. High resolution transmission electron microscopy analyses reveal the high crystallinity and monodispersity of synthesized nanoparticles. Size ranging from 6.5 to 16 nm were obtained in different synthesis conditions. The long term environmental stability of a selected batch of nanocrystals in the ambient condition was also studied by subjecting the samples to XRD, Raman and HRTEM at different intervals from the date of synthesis. It is inferred that the nanocrystals retained its crystallinity, morphology and composition even after 20 months from the date of synthesis. Results will be discussed in detail.

M.M.PI..22
16:30
Authors : Srikanth Chakaravarthy 1,2, Alain Bulou 2, Mauricio Ortega Lopez 3, Jaime Santoyo Salazar 4
Affiliations : 1 Programa de Doctorado en Nanociencias y Nanotecnología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), No. 2508 Av. IPN, Col. San Pedro Zacatenco, C.P. 07360 Distrito Federal, México 2 l'Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, Université du Maine, 72085 Le Mans Cedex 9 France 3 Sección de Electronica y Estado Solido, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), No. 2508 Av. IPN, Col. San Pedro Zacatenco, C.P. 07360 Distrito Federal, México 4 Departmento de Fisica, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), No. 2508 Av. IPN, Col. San Pedro Zacatenco, C.P. 07360 Distrito Federal, México

Resume : Green synthesis and characterization of silver telluride (Ag2Te) nanoparticles have been carried out for the first time to best of our knowledge. We present the synthesis process, structural, morphological and compositional characterizations of the nanoparticles. A predefined process was adapted by replacing 1-dodecanethiol with powders of curcuma longa, a natural reducing agent. The as-synthesized materials were washed several times with deionized water and anhydrous ethanol, and re-dispersed in toluene. Further investigations have been carried out on drop-cast films deposited onto a chosen substrate. Field emission scanning electron microscope (FESEM-EDX) analyses reveal nearly stoichiometric Ag2Te nanomaterials. Transmission electron microscopy (TEM) reveals that most of the prepared Ag2Te nanoparticles are within a size range of 6-10 nm, along with some large nanoparticles of about 15-20 nm range. Optical properties and interaction of natural agent with the nanoparticle were also studied by subjecting the Ag2Te to Absorption, FTIR and Raman spectroscopy techniques. Results will be discussed in detail.

M.M.PI..23
16:30
Authors : Peter Robaschik 1, Michael Fronk1, Svetlana Klyatskay 2, Mario Ruben 2,3, Dietrich R.T. Zahn1, Georgeta Salvan 1
Affiliations : 1 TU Chemnitz, 09126 Chemnitz, Germany 2 KIT, 76344 Eggenstein-Leopoldshafen, Germany 3 ICPMS, 67034 Strasbourg, France

Resume : The single molecule magnet (SMM) terbium(III) bis(phthalocyanine) is considered as a promising candidate for spintronic applications. In this work, films with thicknesses below 100 nm were deposited by organic molecular beam deposition on ferromagnetic, in-plane magnetized Co films. The (magneto-)optical properties were investigated by means of variable angle spectroscopic ellipsometry (VASE) and magneto-optical Kerr effect (MOKE) spectroscopy at room temperature. The molecular orientation was determined from the degree of uniaxial anisotropy of the optical constants and from the amplitude of the magneto-optical Voigt constant. The magnetic coupling of the molecules with the substrate is investigated by MOKE magnetometry in the temperature range from 4 K to 300 K.

M.M.PI..26
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Spin-effect materials : Frank Schramm
08:30
Authors : Herre van der Zant
Affiliations : Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands

Resume : By merging the fields of molecular magnetism, molecular electronics and nanotechnology, we fabricate planar three-terminal nanodevices containing individual magnetic molecules. Source and drain electrodes are made of Au or of (multi-layered) graphene. A third gate electrode allows the modification of charge transport independently from the source/drain electrodes. In this way, a spin transistor is built in which the electric current through the individual magnetic molecule. The molecular complexes of interest are single-molecule magnets (SMMs) and spin-crossover compounds [1]. At cryogenic temperatures Coulomb blockade is generally observed including finer details such as Kondo correlations and excited states [2]. In a Fe-4 SMM based transistor, we observe features that confirm the high-spin state and find Kondo behavior and a zero-field splitting that depends on the redox state; in the charged state the molecule turns out to be a better magnet [3]. Using an in-situ sample rotator, direct observation of magnetic anisotropy has been demonstrated [4]. Work supported by FOM and through the FET EU FP7 program (ELFOS) and an ERC advanced grant (Mols@Mols); email: h.s.j.vanderzant@tudelft.nl. [1] V. Meded et al., Phys. Rev. B 83 (2011) 245115; F. Prins et al. Adv. Mat. 23 (2011) 1545. [2] H.B. Heersche et al., Rev. Lett. 96 (2006) 206801; E.A. Osorio et al., Nano Letters 10 (2010) 105; J.M. Thijssen and H.S.J. van der Zant, Phys. stat. sol. (b) 245 (2008) 1455-1470. [3] A. Zyazin et al. Nano Letters 10 (2010) 3307. [4] E. Burzurí, A.S. Zyazin, A. Cornia and H.S.J. van der Zant, Phys. Rev. Lett. 109 (2012) 147203.

M.M.IV..1
09:30
Authors : E. Saitoh (1)-(3)
Affiliations : (1) WPI-AIMR, Tohoku University, Sendai 980-8577, Japan; (2) Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan; (3)ASRC, Japan Atomic Energy Agency, Tokai 319-1195, Japan

Resume : Spin current, a flow of electrons? spins in a solid, is the key concept in spintronics that will allow the achievement of efficient magnetic memories, computing devices, and energy converters. I here review phenomena which allow us to use spin currents in insulators [1]: inverse spin-Hall effect [2,4], spin pumping, and spin Seebeck effect [4-6]. We found that spin pumping and spin torque effects appear at an interface between an insulator YIG and Pt. Using this effect, we can connect a spin current carried by conduction electrons and a spin-wave spin current flowing in insulators. We demonstrate electric signal transmission by using these effects and interconversion of the spin currents [1]. Seebeck effect (SSE) is the thermal spin pumping [5]. The SSE allows us to generate spin voltage, potential for driving nonequilibrium spin currents, by placing a ferromagnet in a temperature gradient. Using the inverse spin-Hall effect in Pt films, we measured the spin voltage ge nerated from a temperature gradient in various ferromagnetic insulators. This research is collaboration with K. Ando, K. Uchida, Y. Kajiwara, S. Maekawa, G. E. W. Bauer, S. Takahashi, and J. Ieda. REFERENCES [1]. Y. Kajiwara & E. Saitoh et al. Nature 464 (2010) 262. [2] E. Saitoh et al., Appl. Phys. Lett. 88 (2006) 182509. [3] A. Ando & E. Saitoh et al., Nature materials 10 (2011) 655 -659. [4] K. Uchida & E. Saitoh et al., Nature 455 (2008)778. [5] K. Uchida & E. Saitoh et al., Nature materials 9 (2010) 894 - 897. [6] K. Uchida & E. Saitoh et al., Nature materials 10 (2011) 737-741.

M.M.IV.4
 
Charge transport in devices : Bernhard Schäfer
10:30
Authors : Luis E. Hueso, Marco Gobbi, Xiangnan Sun, Amilcar Bedoya-Pinto, Felix Casanova
Affiliations : CIC nanoGUNE; IKERBASQUE Basque Foundation for Science

Resume : Materials based on carbon have recently caught the attention of spintronics, and significant efforts are being made towards their integration in this field. One of their most attractive aspects for spintronic applications is the weakness of their spin scattering mechanisms, implying that the spin polarization of the carriers can be maintained for a very long time in these materials. Noticeably, spin relaxation times of miliseconds have been reported by different techniques, these values exceeding by orders of magnitude the characteristic times detected in inorganic materials. In this talk, I will present results with a prototypical spintronic device (the spin valve), in which a molecular active layer was sandwiched between two ferromagnetic materials. I will show how two very different molecules, namely C60 fullerene and bathocuproine or BCP, are capable or maintaining the coherence of the spin of the injected carriers for more than 60 nm at room temperature. In the case of the fullerene, the room temperature magnetoresistance data is consistent with a multistep tunneling regime. In the case of the BCP, we highlight the differences between spin tunneling and transport in molecular levels. The chemical stability of this molecule, even under ambient conditions, could make it very attractive for potential molecular spintronic We expect our results to be reproduced by other molecular semiconductors, opening novel pathways for the further development of molecular spintronics.

M.M.V..1
11:00
Authors : Yutaka Wakayama, Ryoma Hayakawa, Toyohiro Chikyow
Affiliations : International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS)

Resume : A main purpose is to develop electron-tunneling devices by taking advantages of molecular functions. A key point is to integrate organic molecules into Si-based device architecture for practical device development. Here, we discuss a fundamental mechanism, multi-level control and optical switching of electron tunneling through molecules. In general, quantum dots for the tunneling devices should be well controlled. In fact, size uniformity is important for controlling threshold voltage (Vth) for electron tunneling. To meet these requirements, we adopted organic molecules as quantum dots. First, C60 molecules were embedded in a Au/Al2O3/C60/SiO2 multilayer to form a double-tunneling junction on a Si substrate, in which C60 molecules work as intermediate electrodes. Staircases in a current-voltage curve were observed, and we elucidated that the observed staircases can be attributed to resonant tunneling through the empty and occupied energy levels of the molecules. These results indicate that the Vth can be tuned precisely by designing molecular structure. Furthermore, these results have been expanded to multi-level tunneling and optically controlled-tunneling by using multiple heterogeneous phthalocyanine molecules and photochromic molecules, respectively.

M.M.V..2
11:30
Authors : Pierre Seneor, Marta Galbiati, Marie-Blandine Martin, Sophie Delprat, Bruno Dlubak, Sergio Tatay, Clément Barraud, Eric Jacquet, Cyrile Deranlot, K. Bouzehouane, A. Anane, Albert Fert, Richard Mattana and Frédéric Petroff
Affiliations : Unité Mixte de Physique CNRS/Thales & Université de Paris Sud 91767 Palaiseau, France

Resume : Spintronics is a paradigm focusing on spin as the information vector in fast and ultra-low-power non volatile devices such as the new STT-MRAM. Beyond its widely distributed application in data storage it aims at providing more complex architectures and a powerful beyond CMOS solution. Very recently, molecular spintronics, a rising research field at the frontier between organic chemistry and spintronics, has opened novel and exciting opportunities in terms of functionalities and performances for spintronics devices. Beyond, plasticity and low cost, carbon based materials such as graphene and nanotubes were first seen as very promising for spintronics devices due to their expected long spin lifetime and potential for becoming the ultimate spintronics media. It was only very recently that new spintronics tailoring opportunities that could be brought by molecules and molecular engineering were unveiled. We will present experimental results unveiling promising uses of carbon based molecules for spintronics. We will show that while graphene has potential for unprecedented highly efficient spin information transport [1], the molecular structure, the local geometry at the molecule-electrode interface and more importantly the ferromagnetic metal/molecule hybridization can strongly influence interfacial spin properties going from spin polarization enhancement to its sign control in spintronics devices [2]. Spin dependent transport measurements on ferromagnet/molecules/ferromagnet magnetic tunnel junctions where molecules are organic semiconductors (Alq3) or self-assembled monolayers [3] highlighting the crucial role of the interface will be presented. In addition we will show that a thin graphene passivation layer can prevent the oxidation of a ferromagnet, enabling its use in novel humide/ambient low-cost processes for spintronics devices for molecular spintronics. We will show that graphene coating doesn’t spoil the highly surface sensitive spin current polarizer/analyzer behavior, but more importantly adds a new enhanced spin filtering property [4]. This work was funded through the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement 263104 and 285275. REFERENCES [1] B. Dlubak et al., Nature Physics 8, 557 (2012); P. Seneor, et al., MRS Bulletin 37, 1245 (2012) [2] C. Barraud et al., Nature Physics 6, 615 (2010) [3] M. Galbiati, Adv. Mater. 24, 6429 (2012), S. Tatay et al., ACS Nano 6, 8753 (2012) [4] B. Dlubak et al., ACS Nano 6, 10930 (2012); R. Weatherup, et al., ACS Nano 6, 9996 (2012)

M.M.V..4
 
Single Molecule Magnets : Svetlana Klyatskaya
15:30
Authors : Wolfgang Wernsdorfer
Affiliations : Institut Neel, CNRS, BP 166, 38042 Grenoble, France

Resume : We will address the field called molecular quantum spintronics, which combines the concepts of spintronics, molecular electronics and quantum computing. Various research groups are currently developing low-temperature scanning tunnelling microscopes to manipulate spins in single molecules, while others are working on molecular devices to read and manipulate the spin state and perform basic quantum operations. The talk will discuss this - still largely unexplored - field and present our first results. For ex., we have built a novel spin-valve device in which a non-magnetic molecular quantum dot, consisting of a single-wall carbon nanotube contacted with non-magnetic electrodes, is laterally coupled to a TbPc2 molecular magnet. The localized magnetic moment of the SMM led to a magnetic field-dependent modulation of the conductance in the nanotube with magnetoresistance ratios of up to 300% below 1 K. Using a molecular spin-transistor, we achieved the electronic read-out of the nuclear spin of an individual metal atom embedded in a single-molecule magnet (SMM). We could show very long spin lifetimes (> 10 seconds). Using the hyperfine Stark effect, which transforms electric fields into local effective magnetic fields, we could not only tune the resonant frequency by several MHz, but we also performed coherent quantum manipulations on a single nuclear qubit faster than a μs by means of electrical fields only, establish the individual addressability of identical nuclear qubits.

M.M.VII..1
16:15
Authors : M. Golecki,a J. Lach,a A. Jeremies,a F. Lungwitz,b M. Fronk,b P.Robaschikb G. Salvan,b D. R. T. Zahn,b J. Park,c,d Y. Krupskaya,d V. Kataev,d R. Klingeler,c B. Büchner,d B. Mahns,d M. Knupfer,d P. Siles,d O. G. Schmidt,d A. Reis,e W. R. Thiel,e D. Breite,f B. Abel,f and B. Kersting,a,*
Affiliations : a) Universität Leipzig, D-04103 Leipzig, Germany, b) Technische Universität Chemnitz, D-09107 Chemnitz, Germany c) University of Heidelberg, D-69120 Heidelberg, Germany d) IFW Dresden, D-01171 Dresden, Germany e) TU Kaiserslautern, D-67663 Kaiserslautern, Germany f) Leibniz-Institut für Oberflächenmodifizierung e. V., D-04318 Leipzig, Germany

Resume : A new strategy for the fixation of redox-active dinickel(II) complexes with high-spin ground states to gold surfaces was developed. The complexes were fully characterized by ESI mass spectrometry, IR, and UV/vis spectroscopy, X-ray crystallography (2BPh4 and 4BPh4), cyclic voltammetry, SQUID magnetometry, and HF-ESR spectroscopy. Temperature-dependent magnetic susceptibility measurements reveal a ferromagnetic coupling J=+15.9 and +17.9 cm−1 between the two NiII ions in 2ClO4 and 4BPh4 (H=−2JS1S2). HF-ESR measurements yield a negative axial magnetic anisotropy (D<0), which implies a bistable (easy axis) magnetic ground state. The binding of the [Ni2L(dppba)]ClO4 complex to gold was ascertained by four complementary surface analytical methods: contact angle measurements, atomic-force microscopy, X-ray photoelectron spectroscopy, and spectroscopic ellipsometry. The results indicate that the complexes are attached to the Au surface through coordinative AuP bonds in a monolayer.

M.M.VII..3
17:45
Authors : Karolina Z. Milowska, Jacek K. Stolarczyk,
Affiliations : 1)Photonics and Optoelectronics Group, Ludwig-Maximilians-Universität München, Amalienstr. 54, 80799 Munich, Germany 2)Nanosystems Initiative Munich (NIM), Schellingstr. 4, 80799 Munich, Germany; 1)Photonics and Optoelectronics Group, Ludwig-Maximilians-Universität München, Amalienstr. 54, 80799 Munich, Germany 2)Nanosystems Initiative Munich (NIM), Schellingstr. 4, 80799 Munich, Germany

Resume : Metal nanoparticles possess unique chemical, optical, electrical and magnetic properties unavailable in their bulk limit. Their novel hierarchically-ordered nanoparticles assemblies attract a lot of research activity because of wide range of potential applications. We present results of extensive and systematic studies of periodically assembled (1D, 2D & 3D) ligand-protected Au nanoparticles. Our studies are based on the ab initio calculations in the framework of the density functional theory (DFT) and provide valuable quantitative predictions that are of importance for the design of functional devices. We have performed calculations for 7 different gold clusters (Au13, Au16, Au19, Au38, Au55, Au79 and Au144) protected with different lengths of thiolate ligands (-S(CH2)nCH3, n=0,..,7). We have studied the ligand binding to the surface of Au cluster with respect to surface curvature, crystal orientation and the ligand length. Furthermore, we have calculated adsorption and binding energies as the measure of the stability of those systems. For the assemblies we have also determined the dependence of interparticle interaction potential on particle separation, which is essential for studies of self-assembly process.

M.M.VIII..4
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09:00
Authors : N. Crivillers,1,2 C. Munuera,1 M. Paradinas,1 M. Mas-Torrent,1,2 C. Simão,1,2 S. T. Bromley,3,4 C. Ocal,1 C. Rovira,1,2 J. Veciana1,2
Affiliations : 1 Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra,Spain. 2 Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) ICMAB-CSIC,Bellaterra,Spain. 3 Departament de Quıímica Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona,08028 Barcelona, Spain. 4 Institució Catalana de Recerca i Estudis Avançats (ICREA),08010 Barcelona, Spain

Resume : The work presented here is embedded in the field of Molecular Electronics[1] For the preparation of functional organic materials devoted to be integrated in devices for application in molecular electronics we employ the molecular bottom up approach. The ultimate goal of this approach is to employ functional building blocks to construct nanometer scale devices addressed to specific applications. Furthermore, for practical device implementation the immobilisation of functional molecules on suitable surfaces is also often required. One powerful and versatile strategy for the modification of surfaces at the molecular level is via the preparation of self-assembled monoalyers (SAMs). The use of SAMs as components in electronic devices has attracted great attention from researchers of different fields. In some cases the SAM is used to modulate the performance of the device but, it can also be employed as the electro-active component, i.e., the functionality of the device relies on the properties of the molecules forming the SAM. Our research is focused on the preparation of SAMs based on functional molecules that show bi-stability and hence can act as molecular switches. Magnetic and electroactive molecules have been grafted on a substrate and it has been demonstrated that can perform as robust and non-volatile molecular memory devices.[2] In addition, some of our studies rely on the use of unpaired spin-containing molecules which opens the possibility to explore the spin transport properties of these organic systems for information storage.[3] Our charge transport studies rely on the transport properties comparison between two SAMs based on the closed and open-shell forms of polychlorinated triphenylmethyl (PTM) derivatives that exhibit small differences in their molecular structure but strongly differ in their electronic configuration. [1] James R. Heath. Annu. Rev. Mater. Res. 2009, 39, 1-23. b) Special issue. Nat. Nanotechnol. 2013, 8, 377-467. [2] Claudia Simão, Marta Mas-Torrent, Núria Crivillers, Vega Lloveras, Juan Manuel Artés, Pau Gorostiza, Jaume Veciana and Concepció Rovira. Nat. Chem. 2011, 3, 359-363. [3] a) Núria Crivillers, Carmen Munuera, Marta Mas-Torrent, Claudia Simão, Stefan. T. Bromley, Carmen. Ocal, Concepció Rovira, Jaume Veciana. Adv. Mater. 2009, 21, 1177-1181. b) Núria Crivillers, Markos Paradinas, Marta Mas-Torrent, Stefan T. Bromley, Concepció Rovira, Carmen Ocal, Jaume Veciana. Chem. Commun. 2011, 47, 4664-4666.

M.M.IX..2
09:30
Authors : Yannick VIERO, Stéphane LENFANT, David GUERIN, Dominique VUILLAUME
Affiliations : Molecular Nanostructures & Devices Group, Institute for Electronics Microelectronics and Nanotechnology, CNRS & University of Lille, B.P. 60069, 59652, Villeneuve d’Ascq, France

Resume : Switchable molecules are of particular interest in the perspective of molecular electronics, molecular machines or biosensors. One of the main challenges remains the creation of active devices based on those molecular switches. We have previously shown that a new Azobenzene BiThiophene derivative (AzBT) was a good candidate as it was possible to monitor the conductivity of a Self-Assembled Monolayer (SAM) of those molecules upon UV/blue irradiation (365/470 nm) with high conductance ratios up to 7.10^3. We show that AzBT molecules can cap gold nanoparticles. Cycles of UV/blue irradiation produce variations of the absorbance in the ligand region, demonstrating the switching ability of AzBT-AuNPs in solution. We form Nano-Particle Self-Assembled Networks (NPSANs) and transfer them on silicon substrates with lithographed electrodes (gaps from 30 nm to 200 µm). The nanoparticles here act as a controlled template bridged by interdigitated AzBT molecules. Electrical measurements show conductance variations of NPSANs upon UV/blue irradiations. The current switches from an “on” to an “off” state, associated to a cis/trans-isomerization of the molecules. We repeatedly photoswitched the conductance with typical “on/off” ratios of 6, improving previous literature results (“on/off” ratio < 2).2 Work financially supported by EU FET project SYMONE (n° 318597) and ANR SYNAPTOR (n° 12-BS03-010). 1 Smaali et al., ACS Nano 4, 2411 (2010) 2 Van der Molen et al., Nano Letters 9, 76 (2009)

M.M.IX..4

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No abstract for this day