Abstract: Recently, owing to the superior optical and electrical properties, bioinspired artificial synapses based on two-dimensional (2D) materials have emerged as a vital solution to overcome the inherent inefficiency of conventional von Neumann architecture via photonic neuromorphic computing. Compared with most optoelectronic synapses which rely on metal-semiconductor-metal (MSM) or homo/heterojunction structures, metal-insulator-semiconductor (MIS) structural synapses are equipped with higher sensitivity, stability, and mature configuration. Herein, we have demonstrated a FLG/h-BN/MoSe₂ tunneling diode for optoelectronic synapse device, which is quite different from the three-terminal electric-controlled MIS structural synapse, with space saving, light-controlling, and low consumption features. The MIS device can be harnessed to emulate the optical inspired synaptic behavior because of the photoconductive effect induced by the hole traps in MoSe₂. Four ways including the controls of the drain-source voltage, the width and interval of light pulse, and the optical power density can effectively realize the transition between short-term memory (STM) and long-term memory (LTM). Additionally, the MIS device has realized a maximum paired-pulse facilitation (PPF) index of 184 % and effectively imitated the learning-forgetting-relearning behavior of human beings. Furthermore, a new type of encryption method is introduced, which improves the security of the visible light communication and provides a potential application for synaptic device. The proposed two-terminal MIS structural optoelectronic synaptic device holds profound potential in future artificial neuromorphic computation and encrypted communication.

Key words: Molybdenum selenide, Optoelectronic synaptic device, Metal-insulator-semiconductor tunneling diode, Encryption method