Bioinspired Flexible\nand Low-Voltage Organic Synaptic\nTransistors for UV Light-Driven Vision Systems

Neuromorphic vision systems, particularly those stimulated\nby ultraviolet\n(UV) light, hold great potential applications in portable electronics,\nwearable technology, biological analysis, military surveillance, etc.\nOrganic artificial synaptic devices hold immense potential in this\nfield due to their ease of processing, flexibility, and biocompatibility.\nIn this work, we have fabricated a flexible organic field-effect transistor\n(OFET) that utilizes chitosan-silver nanoparticles (AgNPs) composite\nmaterial as the active dielectric material. During UV light illumination,\nboth silver nanoparticles and the pentacene layer generate a large\nnumber of charge carriers. The photogenerated carriers lead to a more\nsignificant hole accumulation at the pentacene interface, resulting\nin a current rise. In the absence of light, the trapped electron in\nthe silver nanoparticles persists for a longer duration, preventing\nthe instant recombination with holes. This extended retention of electrons\nleads to the observed synaptic performance of the transistor. The\nuse of aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) as one of the\ndielectric layers enables the device to operate effectively at low\nvoltage (<1 V). The device mimics various crucial synaptic properties\nof the brain, including short-term potentiation and long-term potentiation\n(STP and LTP), paired-pulse facilitation (PPF), spike-duration dependent\nplasticity (SDDP), spike-number dependent plasticity (SNDP), and spike-rate\ndependent plasticity (SRDP), etc. This work introduces an approach\nto develop flexible organic synaptic transistors that operate efficiently\nat low voltages, paving the way toward high-performance, UV light-driven\nneuromorphic vision systems.