Gate-tunable synaptic organic–inorganic hybrid phototransistors enabling optoelectronic memory and neuromorphic functionality

We present an organic–inorganic hybrid phototransistor that emulates tunable synaptic behaviors through optically induced, gate-controlled memory retention. The device integrates a tetracene-based photoactive polymer with an IGZO thin-film transistor to form a heterojunction. Upon illumination, photogenerated electrons transfer into the IGZO channel while holes become trapped in the organic layer, inducing a persistent photogating effect that modulates channel conductance, mimicking synaptic weight adaptation. The applied gate voltage regulates the spatial distribution and release of trapped charges in the organic layer, enabling dynamic synaptic responses under subthreshold biases and stable memory states at negative gate voltages. This mechanism yields high photosensitivity ( 1000s), optical trajectory mapping, and synaptic weight modulation with over 90% accuracy in image recognition tasks. This device demonstrates a promising building block for next-generation neuromorphic optoelectronic systems.