Environmental‐Friendly Self‐Powered Polarization Photodetector Based on Lead‐Free Halide Double Perovskite Single Crystals with Asymmetric Contacts

Abstract 2D lead‐free halide double perovskites (HDPs) are distinguished by their low toxicity and superior stability, offering a promising avenue for environmentally friendly polarization photodetection due to their intrinsic crystal anisotropy and exceptional optoelectronic properties. However, the realization of self‐powered polarization detection using these materials remains in its infancy and requires further development. In this study, impressive self‐powered polarization detection is successfully achieved by constructing 2D lead‐free HDP‐based asymmetric contact photodetectors (PDs), Ag/(BA) ₂ CsAgBiBr ₇ /C (BA = n‐butylamine). By leveraging the potential difference from electrodes with varying work functions, the asymmetric contact PDs exhibit a V _oc of 0.9 V under illumination, facilitating photodetection at self‐powered mode with an impressive detectivity of 3.84 × 10¹⁰ Jones. Furthermore, by combining the intrinsic anisotropy of 2D perovskite (BA) ₂ CsAgBiBr ₇ , the detectors successfully realized self‐powered polarization photodetection, demonstrating a polarization ratio of 1.35. This study insights construction of a self‐powered polarization detector employing asymmetric contact in the domain of lead‐free perovskites, highlighting its reliability and potential for future applications.