Switchable photovoltaic and synaptic dual-mode behaviors in asymmetric MoS 2 Schottky phototransistors

Synaptic phototransistors based on two-dimensional materials play central roles in neuromorphic vision systems. The optoelectronic synergistic mechanisms in such devices remain poorly understood. Here, we report a geometrically asymmetric MoS 2 synaptic Schottky phototransistor and systematically investigate the switchable photovoltaic and synaptic responses mediated by photo-carrier trapping/de-trapping near the dielectric–channel interface. Based on the Shockley–Ramo theorem, the origin of the photovoltaic response at the Au - MoS 2 interface under positive gate voltage was revealed. Under negative gate voltage, the device exhibits significant optoelectronic synaptic characteristics. The gate-controlled trapping/de-trapping of photo-generated holes near the channel–dielectric interface is responsible for the synaptic behaviors. A convolutional neural network architecture was constructed, and the recognition of handwritten letters was demonstrated based on the experimental long-term potentiation and depression data. Our research advances the understanding of the switchable photovoltaic and synaptic properties and offers a feasible strategy for developing self-powered reconfigurable synaptic phototransistors.