High‐Performance Self‐Driven MAPbI3‐MAPbBr3 Perovskite Single Crystal Heterojunction Photodetectors for Ultra‐Sensitive Weak Light Imaging

Abstract The rapid advancement of optoelectronic devices, particularly photodetectors, demands enhanced sensitivity for detecting weak light. In this study, MAPbI 3 ‐MAPbBr 3 perovskite single crystal heterojunctions (SCHs) are fabricated via atomic force bonding using liquid‐phase epitaxy, with polydimethylsiloxane (PDMS) serving as a substrate protector. The resulting SCHs photodetector exhibits self‐driven operation, an ultra‐low dark current, and a high on‐off ratio of 5.8 × 10 4 at 0 V bias. Under weak illumination and 5 V bias, the device achieves a maximum external quantum efficiency of 414.9%. With a remarkable detection rate of 4.5 × 10 13 Jones, the device demonstrates outstanding potential for weak light imaging. Furthermore, the self‐driven SCHs photodetector enables high‐quality imaging under a 445 nm light source at a remarkably low intensity of 2.7 µW cm −2 , without the need for any external power supply.