Ultra-stable, sensitive and broadband photodetector based on large-area 2D bismuth oxyselenide film for multiband image sensing

Two-dimensional (2D) materials have proven to be a highly promising candidate for applications in electronic and optoelectronic devices due to their attractive structure and properties. However, the micron-scale dimensions, random distribution on the substrate, and complex transfer processes of 2D materials inevitably cause difficulties in device integration, which limits practical applications in photodetection. Herein, high-quality 2D Bi₂O₂Se film (2×2 cm) composed of numerous single crystal nanosheets on SrTiO₃ substrate was prepared employing the chemical vapor deposition method. The layered Bi₂O₂Se film features a perfect atomic alignment free of lattice mismatch and a sharp interface with the SrTiO₃ substrate. Afterward, a broadband photodetector based on 2D Bi₂O₂Se film was directly constructed, which covered the ultraviolet, visible and infrared range from 365 to 940 nm and demonstrated a fast response speed of 32 ms and 44 ms, maximum responsivity and detectivity of 136 mA/W and 2×10⁹ Jones. Importantly, fast on/off behavior for 100 cycles and reliable photoresponse after storage in air for 1 year confirmed the excellent cycling stability and air stability of the Bi₂O₂Se photodetector. Furthermore, the Bi₂O₂Se photodetector as a single point sensing pixel was capable to perform high-resolution imaging of “H, I, T” patterns. This research affirms the huge potential of Bi₂O₂Se photodetectors to perform as reliable multi-band detection units in complex systems.