Hydrogel-Enabled Electrochemical Modulation of 2D Single-Crystalline VO2 Films for Flexible Neuromorphic Electronics

초록

Electrolyte-gated transistors (EGTs) based on strongly correlated oxides show great promise as artificial synaptic devices due to their ionic-electronic coupling, which allows for significant conductance modulation, low-bias operation, and long-lasting memory states. However, there has been limited exploration of platelet-based two-dimensional (2D) crystalline VO2 channels that can simultaneously achieve nonvolatile conductance programming, array-level addressability, and flexible neuromorphic functionality. In this study, we present hydrogel-gated EGTs utilizing chemical-vapor-deposition-grown 2D-crystalline VO2 platelet channels. These devices exhibit sub-1 V conductance programming, nonvolatile state retention, and reversible write-retain-erase capabilities at both the single-device and 4 & times; 6 array levels. Spectroscopic analyses provide strong evidence for proton-coupled electrochemical modulation within the VO2 channel. Building on this programmable correlated-oxide platform, we demonstrate a variety of synaptic functions, including paired-pulse facilitation, spike-number-dependent plasticity, spike-rate-dependent plasticity, long-term potentiation/depression, and spike-timing-dependent plasticity. Furthermore, after being transferred to flexible substrates, the devices continue to exhibit robust analog potentiation/depression under tensile and compressive strain, as well as repeated bending. The experimentally determined synaptic weights also support stable handwritten-digit recognition in a simulated neural network. These findings establish hydrogel-gated 2D-crystalline VO2 EGTs as a mechanically compliant and array-addressable correlated-oxide platform for flexible neuromorphic electronics.

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