Optoelectronic synaptic characteristics of a van der Waals WS2/PdSe2 heterostructure

Two-dimensional van der Waals heterostructures provide a versatile platform for multifunctional optoelectronic devices. WS2/PdSe2 heterostructures, characterized by n-type conductive behavior, exhibit persistent photoconductivity in high vacuum under negative gate voltages. This phenomenon has been leveraged to simulate synaptic functions of the human brain, including short- and long-term plasticity. Short-term plasticity was simulated, resulting in paired-pulse facilitation and post-tetanic potentiation indices of approximately 140% and 300%, respectively. By stimulating the WS2/PdSe2 heterostructure with consecutive 1 s light pulses, the learning, forgetting, and re-learning phases associated with knowledge acquisition in the human brain were replicated. Furthermore, the device was demonstrated as an optoelectronic memory, programmable with light pulses and erasable via electrical pulses on the gate electrode.