Advances in optoelectronic artificial synapses

The biological neuromorphic system exhibits a high degree of connectivity to process information. Inspired by function, optoelectronic synapses are expected to pave a way to overcome the von Neumann bottleneck for nonconventional computing, which integrates synaptic and optical-sensing functions for visual information processing and complex learning and memory in an energy-efficient way. Herein, this review summarizes the working mechanisms of light-stimulated artificial synapses, including ionization and dissociation of oxygen vacancies, capture and release of carriers through barriers formed by heterojunctions, capture and release of carriers at the semiconductor and dielectric interface, and phase transition. Then, we present a comprehensive overview of the advanced progress in different material systems, including two-dimensional materials, organic material, metal halide, and metal oxide. The existing application scenarios of various synaptic devices are outlined. Finally, the current challenges and perspective toward the development of optoelectronic artificial synapses are briefly discussed for future applications.