High performance dual-band Bi₂O₂Se/CdS heterojunction photodetector for encrypted optical communication

Layered Bi₂O₂Se nanosheets, characterized by a low bandgap, high electron mobility, and good air stability, have garnered significant attention for their potential applications in electronics and photonics. However, the relatively low photocurrent generated by single Bi₂O₂Se nanosheet photodetectors results in diminished switching ratios and responsiveness, thereby limiting the overall performance of Bi₂O₂Se-based photodetectors. In this study, we report a dual-band heterostructure photodetector constructed from high-quality Bi₂O₂Se nanosheets and CdS nanobelts. This device demonstrates exceptional photodetection performance in both the visible (450 nm) and near-infrared (1150 nm) regions, featuring a high switching ratio, increased responsivity, elevated specific detectivity, large external quantum efficiency, and rapid response speed. Notably, these key parameters exceed those reported in most Bi₂O₂Se-based photodetectors. Importantly, the Bi₂O₂Se/CdS heterostructure photodetector showcases impressive high-resolution imaging capabilities. These findings highlight the promising potential of this device for applications in image sensing and encrypted optical communication.