Toward Efficient Two‐Photon Circularly Polarized Light Detection through Cooperative Strategies in Chiral Quasi‐2D Perovskites

Organic–inorganic hybrid perovskites carry unique semiconducting properties and advanced flexible crystal structures. These characteristics of organic–inorganic hybrid perovskites create a promising candidacy for circularly polarized light (CPL) detection. However, CPL detections based on chiral perovskites are limited to UV and visible wavelengths. The natural quantum well structures of layered hybrid perovskites generate strong light–matter interactions. This makes it possible to achieve near‐infrared (NIR) CPL detection via two‐photon absorption in the sub‐wavelength region. In this study, cooperative strategies of dimension increase and mixed spacer cations are used to obtain a pair of chiral multilayered perovskites (R‐β‐MPA)EA2Pb2Br7 and (S‐β‐MPA)EA2Pb2Br7 (MPA = methylphenethylammonium and EA = ethylammonium). The distinctive bi‐cations interlayer and multilayered inorganic skeletons provide enhanced photoconduction. Moreover, superior photoconduction leads to the prominent NIR CPL response with a responsivity up to 8.1 × 10−5 A W−1. It is anticipated that this work can serve as a benchmark for the fabrication and optimization of efficient NIR CPL detection by simple chemical design. Two chiral multilayered perovskites with alternating cations in the interlayer are unprecedentedly obtained by dimension increase and mixed spacer cations. The distinctive structure gives rise to an enhancement of photoconduction, leading to the high near‐infrared (NIR) circularly polarized light (CPL) responsivity (8.1 × 10−5 A W−1). This work highlights the design flexibility of hybrid perovskites for high‐performance NIR CPL detection.