Optical Monitoring of the Resistive States of a Polyaniline‐Based Memristive Device

Abstract

materials makes the elements cheap and easy to manufacture. Moreover, organic materials allow simple chemical modification of the electrophysical properties and fabrication of flexible and stochastic 3D elements. [15-18] One of the first and most studied types of the organic memristive devices are polyaniline (PANI) based devices. [19-26] The structure and electrophysical properties of the PANI-based memristive devices are described elsewhere. [20] The main active component of the device is a thin PANI film connecting two metal electrodes. The third electrode is a silver wire separated from the film by a layer of solid electrolyte. The silver wire ("gate") is always connected to one of the substrate electrodes ("drain"), while the voltage is applied to the second one ("source"), as shown in Figure 1a. The RS is driven by a voltage-controlled electrochemical reaction at the PANI-electrolyte interface. The device switches to the low resistive state (LRS) under applied voltage exceeding the value of +0.4 V and to the high resistive state (HRS) under applied voltage less than +0.1 V. Its conductivity remains quite stable in the window between these values. Nonzero current at zero bias voltage is an essential and inevitable feature of all redox-based memristive devices. [27] The devices were shown to be stable for at least 10 4 switching cycles and able to hold each programmed resistive state for at least 10 3 s. [28,29] A detailed description of the switching mechanism is previously published. [21,22] During the RS, the insulating leucoemeraldine form of PANI transforms into the conductive emeraldine salt form and vice versa according to the following equation

Organic Bioelectronics Development in Italy: A Review

“…Beside these technological and materials aspects, Italian scientific production was addressed also in the development of new characterization protocols to investigate [ 140 , 141 , 142 ] and/or to trigger neuromorphic functions [ 10 , 130 , 143 ] in organic-based devices.…”

“…The working mechanism of these devices was inevitably associated with the evident color change of PANI due to its electrochromic propriety. The observation of these two independent variables (the color and the redox state obtained by electrical measurements) remained separated until Battistoni et al [ 140 ] and Lapkin et al [ 141 ] developed a spectroscopic and an optical method for correlating the actual conductivity of the PANI thin film with its color ( Figure 12 ). The application of a constant voltage bias to OMDs induces a variation in the conductance which depends on the polarity, amplitude and duration of the pulse.…”

“…( b ): Heatmap of absorbance evolution in time within the active zone under applied voltages of −0.2 and +0.7 V. The grey horizontal line is the silver wire. The “source” electrode is on the top, the “drain” on the bottom of the panel [ 141 ]. Reproduced from D.A.…”

Transparent and Flexible Copper Iodide Resistive Memories Processed with a Dissolution-Recrystallization Solution Technique

“…The crucial aspect of these memories is the use of a type of active material that allows tunability of the resistance states. These materials are classified based on their chemical nature, namely, inorganic: binary/ternary metal oxides and organic: poly­( N -vinylcarbazole), poly­(methylmethacrylate), fluoropolymer, and polyaniline. − Metal oxides are considered more promising than the organic ones because of their environmental stability, ease of processability, and, most importantly, switching stability. The most promising and industrially viable methods of fabricating thin films of metal oxides are vacuum-based techniques, such as pulsed laser deposition, atomic layer deposition, and radio-frequency magnetron sputtering .…”

Towards Sustainable Crossbar Artificial Synapses with Zinc-Tin Oxide

“…Table 1 sumarizes the current state of the art and relates it to the current work. It is also worth noting that materials with other possible resistive switching mechanisms have been reported such as photo-induced [24], electrolyte gated [25] and second-and third-order effects [26]. For real-world applications, device cross bar implementations are necessary.…”