Studies on Sb 2 Se 3 /Perovskite Heterojunction for Broadband and Self‐Powered Photodetector With Optical Logic and Spectral Imaging Capability

ABSTRACT Self‐powered photodetectors are highly attractive for applications in optical communication, imaging, environmental monitoring, and military surveillance due to their negligible power consumption. Herein, a high‐performance self‐powered photodetector based on Sb 2 Se 3 /FA 0.88 Cs 0.12 PbI 3 heterojunction is demonstrated. The optimized heterostructure promotes strong light absorption and facilitates efficient photogenerated carrier separation due to the built‐in electric field at the interface. Consequently, the device exhibits significantly reduced dark current and enhanced photocurrent compared to bare Sb 2 Se 3 and perovskite (PE) devices with broadband response in the visible to the near‐infrared region. The device achieves a high responsivity of 2.42 A/W, a specific detectivity of 2.53 × 10 13 Jones, and an on/off ratio of 10 5 , together with fast response characteristics. Under self‐bias condition, the device maintains a remarkable responsivity of 201 mA/W, a detectivity of 7.13 × 10 12 Jones, and an external quantum efficiency of 61%. The device further demonstrates self‐powered spectral imaging and optical “AND” logic gate operation using 405 and 808 nm light as two independent inputs. Density functional theory and ultraviolet photoelectron spectroscopy confirm favorable band alignment and interfacial charge transfer across the heterojunction. This work demonstrates an effective strategy to develop low dark current, broadband, and self‐powered photodetectors through an optimized heterostructure of chalcogenide with halide perovskites.