Self-powered transparent photodetector for subretinal visual functions of wide-field-of-view and broadband perception

Natural photoreceptors enable color vision in humans, wherein the eyes detect colors and their corresponding intensities via cone and rod photoreceptors, respectively. Herein, we developed an artificial broadband photoreceptor with light-color intensity detection similar to that of natural photoreceptors. The developed photoreceptor operates in the self-powered mode and is capable of broadband perception (365-940 nm). The designed metal-oxide heterojunction (n-ZnO/p-NiO) photoreceptor with a thin tin sulfide layer embedded in between is capable of perceiving various colors. It exhibits good transparency in the visible range and displays excellent integration with flexible substrates, highlighting its potential for use in flexible electronics. The fabricated structure has an exceptional response time (asymptotic to 1 ms) and a wide-field-of-view (150 degrees) compared to the human eye's sensing range (50-100 ms and 108 degrees). The transparent photoreceptor mimics cones and rods to detect a various wavelength-dependent signals and explicitly differentiate between the intensities of the detected signals, respectively. This is further illustrated by employing the developed photoreceptor to detect colors in real time by generating unique signals corresponding to each color. The demonstration provides the proof of concept for self-biased flexible bioelectronics emulating high-performing visual functions of artificial eyes.