Copper-Based Polynary Chalcogenide Thin Film Photodetectors for Infrared Photodetection and Light Communication

High-quality photodetectors are essential for getting external information, especially those operating in the near-infrared range. These devices play a critical role in remote communication systems by effectively converting light into electronic signals effectively. The emerging copper-based chalcogenides have attracted attention for thin film solar cells and self-powered photodetectors. However, they can detect only certain wavelengths of infrared light because of their wide bandgaps. In this work, we prepared a hexahydroxy chalcogenide copper–cadmium-zinc–tin sulfur–selenium (CCZTS) absorber with a narrow bandgap of 0.87 eV. Then, we developed a self-powered CCZTS/cadmium sulfide (CdS) thin film photodetector. Furthermore, the manganese (Mn2+) dopant is incorporated into the CdS buffer layer to improve the heterojunction interface properties. As a result, the devices based on the CCZTS/CdS:Mn heterojunction exhibit high responsivity, reduced dark current, and a fast response speed in the wavelength range of 300–1550 nm. At 1319 nm, it has a responsivity of 0.96 A W–1, a detectivity of 3.79 × 1012 Jones. In addition, the resulting CCZTS-based photodetector is successfully integrated into an optical communication system as an optical signal receiver. Our results demonstrate that it has a significant potential for low-cost infrared photodetection and optical communications.