Organic Electrochemical Transistors for Emulating Short-Term Synaptic Plasticity and Direction Selectivity

Organic electrochemical transistors (OECTs) are now widely investigated for their potential use in brain-inspired neuromorphic computation. In this letter, chitosan-gated OECTs are proposed as the neuromorphic devices. The proton conductive chitosan employed as the dielectric can provide low-voltage operation and synapse-like functions for such device via its electric-double-layer (EDL) capacitive effect. Two wiring schemes are utilized for such devices to emulate two different types of short-term synaptic plasticity: potentiation (STP) and depression (STD). These schemes are further integrated into a novel neuromorphic circuit to implement direction selectivity. The achieved direction selectivity is subsequently employed as a temporal-coding method for the recognition of dynamic handwriting. This study demonstrates the tremendous potential of chitosan-gated OECT in neuromorphic application, and it is expected to accelerate the development of next-generation artificial intelligence systems.