Tailoring the Distinctive Chiral‐Polar Perovskites with Alternating Cations in the Interlayer Space for Self‐Driven Circularly Polarized Light Detection

Chiral hybrid perovskites are recently considered for circularly polarized light (CPL) detection owing to the integration of chiral activity and prominent photoelectric characteristics. However, chiral hybrid perovskites are limited because of the restricted chiral cations; efficient self‐driven CPL detection without external power sources required for halide perovskite photodetectors is desirable but remains scarce. Herein, two alternating cations in the interlayer space of chiral‐polar hybrid perovskites, (R‐β‐MPA)EAPbBr4 and (S‐β‐MPA)EAPbBr4 (MPA = methylphenethylammonium and EA = ethylammonium), are developed via a mixed‐cation approach. These perovskites exhibit chiral characteristics featuring CPL detection with high detectivity. Notably, the chiral‐polar structure gives rise to a built‐in electric field to realize self‐driven CPL detection without an applied voltage, and the photocurrent difference reaches 19% under the right and left CPL irradiation. Moreover, a prominent response time of 300 µs is obtained, which is among the fastest for CPL detection. This work highlights the significance of chemical design in the exploration of new chiral perovskites, which will broaden the scope of chiral materials for high‐performance applications. Chiral polar hybrid perovskites with alternating cations in the interlayer space are designed by a mixed‐cation approach. Benefitting from the photoconductive property and distinctive bulk photovoltaic effect induced by chirality‐driven inversion symmetry breaking, self‐driven circularly polarized light response with the photocurrent difference of 19% and very fast response rate of 300 µs is achieved for these chiral polar hybrid perovskites.