2D BiSeI Nanosheets for Broadband Self‐Powered Photoelectrochemical Photodetector

Broadband photodetectors are essential for the integrated design of next‐generation optical detector devices. Ternary 2D bismuth sulfide semiconductor (BiXI, X = S, Se, Te) is an ideal candidate for broadband photoelectric detection due to its narrow bandgap and excellent electrical transport performance. Here, BiSeI is grown by chemical vapor transport (CVT) method and used in photoelectrochemical (PEC) photodetection. The PEC‐type photodetector based on BiSeI nanosheets has a broadband detection ranging from 350 to 900 nm, displaying a high responsivity of 2.88 mA W −1 , a high detectivity of 1.10 × 10 10 Jones and a fast response time of 7/16 ms at a bias voltage of 0.5 V. Furthermore, the device also exhibits a negligible current density loss after three months, which indicates that it has good stability against air and moisture. In addition, the photodetector can work without bias potential, indicating that it is a good self‐powered device. The results demonstrate that BiSeI is a potential material in self‐powered PEC photodetector.