Negative Differential Resistance, Memory, and Reconfigurable Logic Functions Based on Monolayer Devices Derived from Gold Nanoparticles Functionalized with Electropolymerizable TEDOT Units

Abstract

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 μm apart), and electro-polymerized in situ to form a monolayer film of conjugated polymer with embedded gold nanoparticles (AuNPs). Electrical properties of these films exhibit two interesting naphthalenethiol 8 or with 1-dodecanethiol 9 , a perylene derivative with Au nanoparticles 10 , pentacene films with embedded Au nanoparticles 11;12 . Some of these previous reports claimed, in addition to resistive switching, the observation of a Negative Differential Resistance (NDR) in the device. 3;5;6 However in these previous works, devices have a vertical sandwich structure consisting in a metal/switching layer/metal stack where the hybrid material is localized between top and bottom electrodes. In these devices two approaches were used to form the hybrid material: (i) by mixing the organic material with the nanoparticles in solution and depositing the blend by spincoating on the surface; or (ii) by evaporation of an ultra-thin metallic layer (usually 5 nm) onto the organic layer in order to form metal clusters or nanoparticles 13 . Furthermore, resistive memories and their extension to memristive systems have opened new routes toward innovative computing solutions such as logic-in-memory (implication logic with memristor) 14 , analog computing (threshold logic with memristor 15 ) or neuromorphic computing 16 .Nevertheless, to become attractive, these different approaches require a massive integration of memory elements. If crossbar integration consisting in vertical devices interconnected between metallic lines and columns has been considered as an interesting solutions, its practical realization with standard lithographic technics (i.e. top-down approaches) is facing severe limitations such as wire resistance contribution, crosstalk of memory elements during programming and sneak path during reading. One relatively unexplored solution is to rely on bottom-up approaches based on randomly assembly elements, in which memory functionalities are configured post-fabrication.This idea was initially proposed with the concept of nanocell 17;18;19 but remains in its early steps of development from a practical viewpoint and would benefit from functional and reliable hardware for its implementation.Here, we report on a hybrid organic/gold nanoparticle memory with several advances compared to the devices demonstrated until now: (i) a nanoscale -monolayer thick-planar structure: the hybrid organic/gold nanoparticle material is placed between two coplanar electrodes with characteristic distance smaller than 100 nm; (ii) a bottom-up approach for material synthesis, device fabrication and operation: redox ligands were electro-polymerized in situ (i.e. into the device) to form a monolayer of a conjugated polymer with embedded Au nanoparticles and the memory functionality is def...

Negative Differential Resistance and Hysteresis in Self‐Assembled Nanoscale Networks with Tunable Molecule‐to‐Nanoparticle Ratios

“…A possible model that explains the nonlinear current–voltage characteristics at larger biases for networks containing a higher percentage of molecules can be based on tunneling transport and charge trapping . A modified Simmon's model provides a description of the relationship between tunneling current and the magnitude of applied bias in molecular systems.…”

“…Recently, negative differential resistance (NDR) and hysteresis have aroused significant interest in the field of molecular electronics for applications including oscillators and amplifiers, analog‐to‐digital conversion, switching, memory, and neuromorphic circuitry . NDR and/or hysteresis have been observed using metallic contacts to a molecular monolayer containing nitroamine redox centers, molecular nanowires, and arrays of nanoparticles . Programmability in certain of these array systems can be achieved via applied gate voltage, modifying nanoparticle functionalization, or exposure to light .…”

Organic Memory and Memristors: From Mechanisms, Materials to Devices

“…Later, through further research, by redesigning the polymer structure, nonvolatile behavior can be induced. [61] Charge trapping is an inherent metastable mechanism, and the first neuromorphic device based on charge trapping showed retention of more than 10 3 s. [62] By adding a single layer of functionalized crystalline nanoparticles, the retention time can be extended to 10 5 s. [63]…”

Electrical detection of plasmon-induced isomerization in molecule–nanoparticle network devices

“…Networks of metal nanoparticles linked by molecules (or for short NPSAN: nanoparticles self-assembled network) are very valuable and useful in molecular electronics to study fundamental electron transport mechanisms, as well as to assess their potential applications in nanoelectronics. [1][2] For instance, NPSANs with simple molecules (alkyl chains, short π-conjugated oligomers) have been used to gain new insights in metal-insulator transitions, [3][4] plasmon enhanced photoconductance, [5][6][7] and co-tunneling, [8][9][10][11] while NPSANs with relative complex molecules give access to functional devices such as optically [12][13][14][15] and redox 16 driven molecular switches, molecular memory and negative differential resistance, [17][18] and unconventional computing approaches. Bose et al demonstrated the training of molecule/ nanoparticle networks via genetic algorithms in an alkylthiol capped Au NPs network dominated by Coulomb blockade below 5K.…”