Multi-wavelength optoelectronic synapse based on MoS2/WS2 van der waals heterostructures

Abstract

The utilization of two-dimensional van der waals heterostructures in optoelectronic synapses allows for the integration of information processing and memory, thereby providing novel operating platforms for simulating the perceptual visual systems and developing the neuromorphic computing systems due to its contactless, highly efficient and parallel computing. Herein, we have constructed a straightforward MoS2/WS2 heterostructure optoelectronic synapse and examined its capacity to imitate synaptic behaviors under optical stimulus. The MoS2/WS2 device demonstrated several synaptic functions, such as the excitatory postsynaptic current, short-term plasticity, long-term plasticity, pairs-pulse facilitation and ‘learning-experience’ behavior. Moreover, the MoS2/WS2 synaptic device can achieve a wide range of photo response wavelengths, spanning from UV to visible light, as well as the conversion from short-term plasticity to long-term plasticity. Furthermore, light-induced charge transfer due to adsorption and desorption of oxygen molecules in MoS2/WS2 heterostructure can be used to explain its working mechanism. Additionally, the synaptic plasticity of MoS2/WS2 device can be controlled by adjusting the duration, power and number of the optical pulses, which renders the MoS2/WS2-based optoelectronic synaptic device extremely favorable for implementation in the perceptual visual system.