Multispectral photodetectors based on 2D material/Cs₃Bi₂I₉heterostructures with high detectivity

Group VA metal halide-based perovskites have emerged as intensively explored Pb-free perovskites, owing to their excellent environmental stability and low-toxicity. However, the relatively low carrier mobility and high photocarrier recombination rates restrict their applications in photodetectors. One promising approach to achieve higher performance is to integrate these Pb-free perovskites with 2D materials to form heterostructures. Here, we report on the high sensitivity photodetectors based on MoS₂/Cs₃Bi₂I₉and graphene/Cs₃Bi₂I₉heterostructures for multispectral regions. The heterostructures combine the high carrier mobility of 2D materials with superior light-harvesting properties of perovskites, as well as the effective built-in electric filed at the junction area, leading to efficient photocarrier separation and extraction. The specific detectivity of MoS₂/Cs₃Bi₂I₉device reaches 1.15 × 10¹³Jones for the detection of ultraviolet (UV) light of 325 nm, which is four orders of magnitude higher than UV detectors built on GaN. As a result of the efficient dark current suppression, the specific detectivity of graphene/Cs₃Bi₂I₉photodetector can be promoted to 5.24 × 10¹¹Jones, 1.33 × 10¹¹Jones, and 1.12 × 10¹¹Jones for the detection of 325 nm, 447 nm, and 532 nm light, respectively.