Reconfigurable photovoltaic effect for optoelectronic artificial synapse based on ferroelectric p–n junction

Neuromorphic machine vision has attracted extensive attention on wide fields. However, both current and emerging strategies still suffer from power/time inefficiency, and/or low compatibility, complex device structure. Here we demonstrate a driving-voltage-free optoelectronic synaptic device using non-volatile reconfigurable photovoltaic effect based on MoTe₂/α-In₂Se₃ ferroelectric p–n junctions. This function comes from the non-volatile reconfigurable built-in potential in the p–n junction that is related to the ferroelectric polarization in α-In₂Se₃. Reconfigurable rectification behavior and photovoltaic effect are demonstrated firstly. Notably, the figure-of-merits for photovoltaic effect like photoelectrical conversion efficiency non-volatilely increases more than one order. Based on this, retina synapse-like vision functions are mimicked. Optoelectronic short-term and long-term plasticity, as well as basic neuromorphic learning and memory rule are achieved without applying driving voltage. Our work highlights the potential of ferroelectric p–n junctions for enhanced solar cell and low-power optoelectronic synaptic device for neuromorphic machine vision.