Optogenetics-Inspired Neuromorphic Optoelectronic Synaptic Transistors with Optically Modulated Plasticity

Plasticity modulation, which enables the biological synapses to express rich functionality in a tunable way, is an important technique to comprehensively emulate the synaptic functions for artificial neuromorphic computing systems. However, the reliable modulation on the synaptic plasticity has not been well realized at the device level due to the uncontrollable movement of ions or electrons in solid state electronic materials. Here, inspired by the optogenetics that modifies the synaptic plasticity by optical modulation, the authors propose an optoelectronic synaptic transistor based on MoS2/quantum dots (QDs) mixed-dimensional heterostructure with optically modulated plasticity. The transmission of neuronal signaling in biological retina has been faithfully emulated under the optical modulation, where the post-synaptic current is inhibited in the dark and enlarged upon illumination. Moreover, a light-induced inversion between synaptic potentiation and depression is also demonstrated. Such optical modulation on synaptic plasticity can be attributed to the photo-gating effect dominating the switching characteristics of the MoS2/QDs heterostructure channel under the stimulation of specific electric signals. The authors' results provide a feasible strategy to realize functional diversity under the optical modulation for synaptic transistors and promote the development of a neuromorphic optoelectronic hardware platform.