Anisotropy in a 2D Perovskite Ferroelectric Drives Self‐Powered Polarization‐Sensitive Photoresponse for Ultraviolet Solar‐Blind Polarized‐Light Detection

Abstract Polarized‐light detection in the deep ultraviolet solar‐blind region is indispensable for optoelectronic applications. 2D hybrid perovskite ferroelectrics with inherent anisotropy and bulk photovoltaic effect (BPVE) have become a robust candidate in this portfolio. We here report a wide band‐gap 2D perovskite ferroelectric, (isobutylammonium) 2 (methylamium)Pb 2 Cl 7 ( 1 ), in which the BPVE behaves as self‐driving source for solar‐blind ultraviolet polarized‐light detection. It exhibits a large dichroism ratio (≈15.7) and superior BPVE‐directed photocurrent (≈3.6 μA cm −2 , under 266 nm). These attributes facilitate excellent self‐powered polarized‐light detection of high on/off contrast (≈10 3 ) and polarization ratio (≈2.5), beyond those of inorganic oxides (e.g., ZnO, 1.47; GaN, 1.38). This study highlights potential of 2D perovskite ferroelectrics for new optoelectronic application.