Air Induced Formation of Cs3Bi2Br9/Cs3BiBr6 Bulk Heterojunction and Its Dual-band Photodetection Abilities for Light Communication

Metal-halide perovskites have long carrier diffusion lengths, low trap densities, and high carrier mobilities, and are therefore of value in the development of photodetectors (PDs). However, the research on dual-band lead-free perovskite bulk heterojunction has not been well developed. Here, a novel air induced formation of Cs3Bi2Br9/Cs3BiBr6 bulk heterojunction, reaching a high-performance dual-band photodetecting performance with a UV main band (360 nm) peak responsivity of 5.6 mA W-1 and a blue sub-band (450 nm) peak responsivity of 0.6 mA W-1 at 2 V, is reported. The bulk heterojunction exhibits superior photodetecting performance than that of lateral heterojunction. Furthermore, the PD exhibits a fast response speed (rise time 1.4 mu s and decay time 2.0 mu s) and good cyclic stability. Theoretical and experimental characterizations suggest Cs3Bi2Br9 exhibits a more stable structure in air than that of Cs3BiBr6. The dual-band photodetection abilities of Cs3Bi2Br9/Cs3BiBr6 bulk-heterojunction demonstrate great application prospects in light communication. These state-of-the-art findings shed light on the fabrication of novel dual-band high-performance PDs based on lead-free perovskite bulk-heterojunction.