Hybrid electronic device based on polyaniline-polyethyleneoxide junction

Abstract

A three-electrode hybrid molecular electronic element based on polyaniline ͑PANI͒ emeraldine base-polyethylene oxide/LiCl was fabricated and tested. Source and drain electrodes were connected to the conducting polymer layer. Solid electrolyte was deposited as a narrow stripe over the PANI film, and the third electrode ͑gate͒, maintained at ground potential, was attached to it. Drain and gate currents were measured during a drain voltage sweep. Drain voltage-current characteristics revealed a rectifying behavior, while gate characteristics were similar to those for cyclic voltammograms. Such behavior was attributed to the electrochemical control of the redox state ͑and hence of conductivity͒ of PANI area under the solid electrolyte. The device was stable and reproducible with robust electrical characteristics. In particular, an asymmetry in time relaxation due to ion diffusion was found; a possible application of this to the use of this device in adaptive conducting networks is proposed.

Adaptive polymeric system for Hebbian-type learning

“…In order to induce such reaction, the part of the PANI film must be in a contact with an ions reservoir provided by a poly(ethylene oxide) gel doped with lithium salt kept at ground potential. As previously reported [10], in this system the electrically induced exchange of Li + ions between PEO and PANI is involved in processes responsible for the modulation of the element conductivity; when both ions reservoir and conductive layer are at the same potential the ions migrate spontaneously inside the film reducing the polymer to the insulating form, while on other hand when a positive voltage is applied, the opposite effect takes place resulting in an oxidation of PANI and recovery of its conductive state. The element exhibits therefore a rectifying behavior: when a positive voltage higher than the oxidation potential is applied the conductivity increases while for zero or negative voltage the material is insulating.…”

“…Possible candidates for the task are the so called "memristive" systems which have attracted great interest in the last years [5]. A memristive device is a two terminal element with "memory", to be more precise, using definition [6]: it displays a resistance R(w) function of an internal state variable w whose derivative is a function of the passing current i, as summarized by the two equations: 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 [7], VO 2 [8], or silicon [9] while in our lab an organic system has been developed [10]. The organic device is based on the heterojunction of a thin doped polyaniline (PANI) layer acting as conducting element with an electrical resistance variable through redox reactions, and a thick film of the solid electrolyte PEO: Li + .…”

First steps towards the realization of a double layer perceptron based on organic memristive devices

“…Memristive properties were found in inorganic (such as TiO x , HfO x , SiO x , etc. ), [7][8][9][10] organic (polyaniline, polyimide) 11,12 and hybrid organic/inorganic 13 materials. Organic or polymeric materials have unique advantages over traditional inorganic memristive devices, including high flexibility for biocompatible neuromorphic circuits and implants, low cost, solution processability, large-area implementation.…”

Skeleton-supported stochastic networks of organic memristive devices: Adaptations and learning

“…19,20 Organic memristive devices (our basic element for the adaptive networks) is formed by a heterojunction of conducting polymer and solid electrolyte, in particular, polyaniline (PANI) and polyethylene oxide (PEO) doped with lithium salts. 9 Thus, the formed supported network must contain these materials distributed in a stochastic manner with a statistical probability of forming the desirable contacts of two mentioned materials.…”

“…4 It has been reported several examples when memristive devices were used as electronic analogs of neurons 5,6 and synapses. 7,8 In particular, using the organic memristive device 9 it was reconstructed an electronic circuit, mimicking the architecture and properties of a part of the nervous system of the pond snail Lymnea stagnalis, responsible for the learning of this animal during feeding. 10 In this case Hebbian (synaptic) type of learning 11 was demonstrated in artificially fabricated electronic circuits.…”