A Chemically Programmable Retinomorphic GaN p-n Diode for Multimode Visual Sensing.

Abstract

Real-world visual scenes include wide illumination conditions with rapid fluctuations, demanding vision sensors that integrate multiple visual dynamics through diverse modulation strategies. However, most vision sensors suffer from limited tunability, mainly modulated via external physical stimuli (e.g., electric or light) while lacking chemical programmability critical for biorealistic vision. Here, we report a chemically programmable retinomorphic p-n diode that supports spiking response and light adaptation together with chemical tunability in an ultracompact device platform. Governed by the interplay between photoelectric carrier separation at the internal p-n junction and electrochemical carrier consumption at the semiconductor/electrolyte interface, the retinomorphic diode demonstrates switchable response modes with chemical programmability. Specifically, the device generates spikes upon illumination transitions under closed-circuit operation, while varying ion/molecule species enables bidirectional tuning of steady-state current, transforming dynamic-only sensing into static-dynamic fused sensing. Moreover, it spontaneously shifts from scotopic to photopic adaptation with increasing illumination under open-circuit operation, while both processes can be bidirectionally regulated through chemical programming. Leveraging this adaptive behavior, we further construct a proof-of-concept visual-motor pathway that exhibits chemically programmable, illumination-dependent actuation. Together, this work demonstrates a chemically programmable retinomorphic platform combining physical and chemical modulation for bioinspired multimode visual sensing.