Improved Photoelectric Performance of Cs₂AgSbBr₆ Photodetectors via Bismuth and Cobalt Co-doping for Rapid Light Detection

Recent advancements in photodetector technology have significantly improved device performance and stability. In this study, we developed a high-performance double perovskite photodetector based on Cs₂AgSbBr₆ through systematic bismuth and cobalt co-doping. Initially, bismuth doping was optimized, with Cs₂AgSb_1-xBi_xBr₆ (x=0.35) demonstrating superior optoelectronic properties, including an On/Off ratio of 94.36 and fast response times (decay time = 5.98 ms, rise time = 8.88 ms). The enhanced crystallinity of the perovskite film, attributed to Bi³⁺ incorporation, facilitated improved carrier generation and transport. Building upon this optimized structure, bismuth-cobalt co-doping was introduced to further refine energy level alignment within the device. The co-doped Cs₂AgSb_1-x-yBi_xCo_yBr₆ (x=0.35, y=0.03) photodetector exhibited a significantly On/Off ratio of 117.98 and even faster response times (decay time = 1.96 ms, rise time = 4.51 ms). Characterization and electrochemical analysis revealed that co-doping improved film morphology, crystal quality, and carrier transport efficiency. Moreover, the stable crystal structure of the optimized films contributed to the device’s excellent overall performance. These findings highlight the effectiveness of elemental doping strategies in enhancing perovskite photodetectors, offering a promising approach for next-generation optoelectronic devices.