A retina-inspired carbon dot-based and light-suppressed photochemical memristor

Abstract

For biological retina, the light‐induced suppressive response of photoreceptors constitutes a fundamental mechanism for visual adaptation and inhibitory information encoding. However, it remains difficult to reproduce in artificial neuromorphic photoreceptor systems. Here, we report a retina‐inspired photochemical memristor with intrinsic light‐induced suppression, based on a carbon dot‐polyaniline composite structure (Au/CDot‐PANI/ITO). In dark, the redox transition of PANI, synergistically coupled with CDot‐mediated oxygen reduction reactions, establishes a stable internal proton concentration gradient and generates a spontaneous built‐in electromotive force. Upon light exposure, a photovoltage generated within the composite emerges with an opposite polarity to the dark‐state built‐in potential, effectively suppressing the original current and resulting in pronounced negative photoconductance. These devices exhibit memristive characteristics and synaptic plasticity, where short‐term memory originates from photovoltage‐dominated transient responses, while repeated optical stimulation activates slower photochemical processes that induce persistent proton trapping and interfacial reconstruction, driving the device into a long‐term memory regime characterized by long‐term depression.