Self‐Powered Photodetector Based on Perovskite/Ge Heterojunction with High Responsivity

Abstract Self‐powered photodetectors (SPDs) are regarded as a new type of photodetectors without external energy sources, exhibiting great potential in the next generation of image sensing, biological detection, and robotics. Here, single crystal CH(NH 2 ) 2 PbBr 3 (FAPbBr 3 ) perovskite with a low trap density of 1.64 × 10 9 cm −3 is directly integrated onto single crystal germanium (Ge). The band structure of the heterojunction belongs to type‐II alignment type, which is beneficial to the achievement of high responsivity. Therefore, the fabricated Au/FAPbBr 3 /Ge/Au detector exhibits a high responsivity of 0.33 A W −1 , detectivity up to 3.83 × 10 11 Jones and relatively fast decay time of 4.94 ms without external bias under 520 nm laser illumination. In addition, a prototype of an imaging system is set up utilizing the photodetector as a sensing pixel, from which the imaging function is verified. This work demonstrates a facile strategy for designing high‐performance SPDs.