Realization of High‐Performance Self‐Powered Polarized Photodetection with Large Temperature Window in a 2D Polar Perovskite

Abstract Polarization photodetection taking advantage of the anisotropy of 2D materials shines brilliantly in optoelectronic fields owing to differentiating optical information. However, the previously reported polarization detections are mostly dependent on external power sources, which is not conducive to device integration and energy conservation. Herein, a 2D polar perovskite (CBA) 2 CsPb 2 Br 7 ( CCPB , CBA = 4‐chlorobenzyllamine) has been successfully synthesized, which shows anticipated bulk photovoltaic effect (BPVE) with an open‐circuited photovoltage up to ≈0.2 V. Devices based on CCPB monomorph fulfill a fascinating self‐powered polarized photodetection with a large polarization ratio of 2.7 at room temperature. Moreover, CCPB features a high phase‐transition temperature (≈475 K) which prompts such self‐powered polarized photodetection in a large temperature window of device operation, since BPVE generated by spontaneous polarization can only exist in the polar structure prior to the phase transition. Further computational investigation reveals the introduction of CBA + with a large dipole moment contributes to quite large polarization (17.5 µC cm −2 ) and further super high phase transition temperature of CCPB . This study will promote the application of 2D perovskite materials for self‐powered polarized photodetection in high‐temperature conditions.