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.