Photoelectric synaptic device based on Cu₂ZnSnS₄/ZnO heterojunction for non-volatile vision memory

The advent of artificial photoelectric synapse devices has attracted considerable attention due to their potential to reshape the landscape of neuromorphic computing. A critical challenge impeding their wider application is the typically short image retention time these devices exhibit. In this study, a strategy is developed to address this obstacle by combining the formation of heterojunction and defect-trapping effects. A Cu₂ZnSnS₄ (CZTS) film is prepared via low-temperature annealing to form a type II heterojunction with ZnO. The two-terminal device based on this heterojunction shows excellent synaptic functionality. The wide absorption of CZTS film in the visible light spectrum enables the device to achieve a broadband response, which is crucial for realizing the simulation of Pavlov's associative memory. Its utility in encoding encrypted information is demonstrated through the capability to simulate Morse code. Most importantly, the device exhibits image memory for periods exceeding 1100 s, highlighting its exceptional performance in visual memory retention. These results contribute to the development of CZTS-based photoelectric synaptic devices with broad response characteristics and non-volatile memory capabilities.