Dual-Band Perovskite Bulk Heterojunction Self-Powered Photodetector for Encrypted Communication and Imaging

Self-powered, dual-band photodetection of electromagnetic signals promises wide photoelectric applications in imaging, communication, environmental monitoring, and rescue. However, most reported dual-band photodetectors (PDs) based on various heterojunctions are realized by complex fabrication processes, which may introduce defects in the depletion layer. Here, first, a self-powered dual-band PD based on lead-free perovskite bulk heterojunction (Cs3Bi2Br9/Cs3BiBr6) fabricated by a one-step spatial confinement method is demonstrated. Its two peaks of self-powered responsivities are 59.4 mA W-1 at 360 nm and 3.09 mA W-1 at 450 nm. A high on/off ratio (18881), fast response speed (rise time 200 ns; decay time 1.09 mu s), high detectivity (1.2 x 10(12) Jones), and cycle stability are realized under UV band, which exceeds most reported state-of-the-art lead-free halide perovskite PDs. The dual-band PD is suitable for encrypted communication and image sensing. This research represents a new frontier in the search for novel dual-band high-performance PDs based on lead-free perovskite bulk heterojunction fabricated by low-cost and simple fabrication methods.