Optogenetics-Inspired Tunable Synaptic Functions in Memristors.

Two-terminal memristors with internal Ca2+-like dynamics can be used to faithfully emulate biological synaptic functions and have been intensively studied for neural network implementations. Inspired by the optogenetic technique that utilizes light to tune the Ca2+ dynamics and subsequently the synaptic plasticity, we develop a CH3NH3PbI3 (MAPbI3)-based memristor that exhibits light-tunable synaptic behaviors. Specifically, we show that by increasing the formation energy of iodine vacancy (VI·/VI×), light illumination can be used to control the VI·/VI× generation and annihilation dynamics, resembling light-controlled Ca2+ influx in biological synapses. We demonstrate that the memory formation and memory loss behaviors in the memristors can be modified by controlling the intensity and the wavelength of the illuminated light. Coincidence detection of electrical and light stimulations is also implemented in the memristive device with real-time (≤20 ms) response to light illumination. These results open options to modify the synaptic plasticity effects in memristor-based neuromorphic systems and can lead to the development of electronic systems that can faithfully emulate diverse biological processes.