Co‐Evaporated Ratio‐Tunable Te _x Se _1‐x Film for High‐Performance Multiband Photodetection Toward Subretinal Color Visual Functions

ABSTRACT The human visual system perceives fundamental visual information, including light intensity, color, and spatial patterns, providing a foundation for the development of biomimetic optoelectronic devices. Among these devices, photodetectors play a central role in constructing biomimetic visual perception systems. A single photodetector typically outputs a photocurrent proportional to the incident light intensity but does not extract information from the incident light. Herein, we design a biomimetic color vision system based on three distinct devices, each featuring the architecture ITO/ZnO/Te _x Se _{1‐ x} /Te _0.7 Se _0.3 /Au, where x varies as 0.3, 0.48, and 0.55. The Te _x Se _{1‐ x} films are prepared via co‐evaporation. By fabricating Te _x Se _1‐x /Te _0.7 Se _0.3 ( x = 0.3, 0.48, and 0.55) stacks in situ with gradient band structures, a minimum dark current density of 1.86 × 10 ⁻⁶ mA cm ⁻² and an external quantum efficiency exceeding 90% at a wavelength of 450 nm are achieved at x = 0.3. Notably, the distinct photoresponse of the three device types enables the mimic of cone cell functionality, allowing the precise recognition of incident light wavelength. The calculated wavelength error is less than 0.4%. Our study successfully mimics the color recognition behavior of the human visual system, providing useful guidance for the design of future biomimetic visual devices.