TiO2 Nanocrystal/Perovskite Bilayer for High-Performance Photodetectors

Owing to their attractive performance in photovoltaic devices, organolead halide perovskite materials have attracted enormous interest for photodetector applications. However, current perovskite-based photodetectors mainly rely on high-conductive 2D materials such as graphene or transition metal sulfides to transport photocarriers, which indeed significantly improve the photoresponsivity but seriously weaken other parameters such as on/off ratio or response speed. Achieving a high overall performance remains a challenge. Here, a solution-processed TiO2 nanocrystal (NC) film is employed to transport photocarriers. The designed TiO2 NC/perovskite (CH3NH3PbI3) bilayer device exhibits satisfactory overall performance with on/off ratio of 4000, photodetectivity of 1.85 x 10(12) Jones, and rise/decay time of 0.49/0.56 s. The device can also be integrated on flexible polyimide substrate. This work provides a strategy to realize high-performance perovskite-based photodetectors and clearly demonstrates their potential applications in future flexible optoelectronics.