All-Optically Controlled Positive and Negative Photoresponses for Artificial Visual Adaptation and Protection

• • The ZnO/MAPbBr3 heterojunction achieves reversible switching between positive and negative photoconductivity under visible light, controlled solely by ultraviolet light modulation of oxygen vacancy states, enabling all-optical adaptation without external gate bias. • • The device emulates scotopic adaptation (photopigment regeneration) and photopic adaptation (photopigment bleaching) within a single two-terminal structure, demonstrating multi-level visual function integration. • • Leveraging negative photoconductivity, the device exhibits an eyelid-like self-protection mechanism under intense light exposure, providing inherent optical safety without complex circuitry. • • The tunable photoconductive behavior arises from the competition between intrinsic photoconduction and trap-mediated carrier capture, with oxygen vacancies acting as the key trapping centers, as confirmed by experimental results.