Self-Powered and Broadband Optical Synapse Device Based on Se-Vacancy Bi₂O₂Se for Artificial Vision System Application

The optical synaptic devices, inspired by the human visual system and capable of emulating biological synaptic behaviors, have demonstrated significant potential for artificial vision applications. However, contemporary optical synaptic devices are hindered by several limitations, including a narrow response range, intricate structures, compromised stability, and substantial energy demands. Herein, large single-crystal Bi2O2Se nanosheets with selenium vacancies (Bi2O2Se–VSe) were synthesized via physical vapor deposition. Based on the Bi2O2Se–VSe nanosheet, a self-powered, broadband optical synaptic device was developed simply by a straightforward asymmetric contact approach. The device proficiently replicates synaptic functionalities without any electrical power requirement. Furthermore, an artificial vision system comprising a 5 × 5 array of self-powered optical synaptic devices was constructed. Under illumination at wavelengths of 350, 532, and 1050 nm for 100 s, the intensity of the image pattern can be kept at a high memory level of 94.91%, 44.92%, and 12.83% after attenuation of 100 s, which demonstrates the excellent image sensing, learning, and memory storage properties. This research paves the way for further exploration of optical synaptic devices and contributes novel insights into the development of artificial vision systems.