Interface Dipole : Effects on Threshold Voltage and Mobility for both Amorphous and Poly-crystalline Organic Field Effect Transistors

We report a detailed comparison on the role of a self-assembled monolayer (SAM) of dipolar molecules on the threshold voltage and charge carrier mobility of organic field-effect transistor (OFET) made of both amorphous and polycrystalline organic semiconductors. We show that the same relationship between the threshold voltage and the dipole-induced charges in the SAM holds when both types of devices are fabricated on strictly identical base substrates. Charge carrier mobilities, almost constant for amorphous OFET, are not affected by the dipole in the SAMs, while for polycrystalline OFET (pentacene) the large variation of charge carrier mobilities is related to change in the organic film structure (mostly grain size).Comment: Full paper and supporting informatio

Negative Differential Resistance, Memory and Reconfigurable Logic Functions based on Monolayer Devices derived from Gold Nanoparticles Functionalized with Electro-polymerizable Thiophene-EDOT Units

We report on hybrid memristive devices made of a network of gold nanoparticles (10 nm diameter) functionalized by tailored 3,4(ethylenedioxy)thiophene (TEDOT) molecules, deposited between two planar electrodes with nanometer and micrometer gaps (100 nm to 10 um apart), and electropolymerized in situ to form a monolayer film of conjugated polymer with embedded gold nanoparticles (AuNPs). Electrical properties of these films exhibit two interesting behaviors: (i) a NDR (negative differential resistance) behavior with a peak/valley ratio up to 17, and (ii) a memory behavior with an ON/OFF current ratio of about 1E3 to 1E4. A careful study of the switching dynamics and programming voltage window is conducted demonstrating a non-volatile memory. The data retention of the ON and OFF states is stable (tested up to 24h), well controlled by the voltage and preserved when repeating the switching cycles (800 in this study). We demonstrate reconfigurable Boolean functions in multiterminal connected NP molecule devices.Comment: Full manuscript, figures and supporting information, J. Phys. Chem. C, on line, asap (2017

Metal/organic/metal bistable memory devices

We report a bistable organic memory made of a single organic layer embedded between two electrodes, we compare to the organic/metal nanoparticle/organic tri-layers device [L.P. Ma, J. Liu, and Y. Yang, Appl. Phys. Lett. 80, 2997 (2002)]. We demonstrate that the two devices exhibit similar temperature-dependent behaviors, a thermally-activated behavior in their low conductive state (off-state) and a slightly "metallic" behavior in their high conductive state (on-state). This feature emphasizes a similar origin for the memory effect. Owing to their similar behavior, the one layer memory is advantageous in terms of fabrication cost and simplicity

Functionalized Gold Nanoparticles with Electropolymerizable π-Conjugated Systems for a Neuro-inspired Memristive Nanoparticle Organic Synapse-Transistor

Nanoparticle Organic Memory Field-Effect Transistors (NOMFET) are molecule-based devices that exhibit the main behavior of a biological spiking synapse. This behavior is obtained by virtue of the combination of two properties of the NOMFET: the transconductance gain of the transistor and the memory effect due to the presence of nanoparticles (NPs) which are used as nanoscale capacitors to store the electrical charges, and which are embedded into an organic semiconducting layer [1]. Thus, the transconductance of the transistor can be dynamically tuned by the amount of charge in the NPs. In this context, we present here a novel method for the elaboration of NOMFET active materials based on the electrochemical deposition of gold NPs grafted with alkanethiol-terminated π-conjugated precursors combining low oxidation potential and high reactivity. The straightforward electropolymerization of these new precursors leads to the formation of a semiconducting network in which the electronic and transport properties and the charging/discharging speed of the gold NPs can be modulated. Such hybrid material could advantageously replace the pentacene layer generally used in NOMFETs. This novel approach is based on previously demonstrated enhancement of charge-tunneling across monolayers of SAMs of alkanethiol-bithiophenic systems on a planar gold surface after electrochemical conversion into more extended conjugated systems [2]. The synthesis of the precursors and nanoparticles will be described and the morphology and electronic properties of the hybrid electropolymerized films will be discussed with regard to the behavior of the resulting NOMFET-devices. [1] F. Alibart, S. Pleutin, D. Guerin, C. Novembre, S. Lenfant, K. Lmimouni, C. Gamrat, D. Vuillaume, Adv. Funct. Mater. 2010, 20, 330-337. [2] M. Oçafrain, T. K. Tran, P. Blanchard, S. Lenfant, S. Godey, D. Vuillaume, J. Roncali, Adv. Funct. Mater. 2008, 18, 2163-2171

Oligothiophene-derivatized azobenzene as immobilized photoswitchable conjugated systems

Immobilization of an azobenzene-bithiophene compound on a gold surface leads to self-assembled monolayers with photoswitchable electrical properties

Structural Control of the Horizontal Double Fixation of Oligothiophenes on Gold

Quaterthiophenes bearing one (1) or two (2) alkanethiol chains attached at the internal β-position of the outermost thiophene ring through a sulfide linkage have been synthesized. Cyclic voltammetric analysis of their electrochemical behavior in solution suggests that electrooxidation of the doubly substituted oligomer 2 leads to electrodeposition of a poly(disulfide) on the anode surface. Monolayers of 1 or 2 on gold surfaces have been investigated and characterized by cyclic voltammetry, ellipsometry, contact angle measurement, and X-ray photoelectron spectroscopy. The results of these investigations indicate that introduction of two thiol groups in the structure leads to double fixation of the oligothiophene chain with the main axis of the conjugated system oriented parallel to the surface. The effects of single versus double fixation of the quaterthiophene chain on the electrochemical properties and stability of the corresponding monolayers are discussed

High on-off conductance switching ratio in light-driven self-assembled molecular devices

Date du colloque : 5-9/01/2010International audienc

OPTOSAM: Surfaces aux propriétés électroniques réversiblement modifiables par stimulation optique

Date du colloque&nbsp;: 10/2008</p