Interlayer Polymerization of 2D Chiral Perovskite Single‐Crystal Films toward High‐Performance Flexible Circularly Polarized Light Detection.

2D chiral perovskite has greatly boosted the development of optoelectronic devices, ranging from nonlinear optics, spintronics, and ferroelectrics to energy harvesting devices. Despite circularly polarized light (CPL) detection based on chiral perovskite has been achieved, the environmental humidity‐, ultraviolet (UV), and temperature‐induced structural degradation and its large electro‐phonon coupling restrict its commercial application. Here, this study first realizes polymerized chiral perovskite single‐crystal films by combining in situ cross‐linking polymerization with the space‐confined crystallization method. Compared with uncross‐linked chiral perovskites, cross‐linked chiral perovskites exhibit enhanced crystallinity and lattice rigidity, yielding high‐performance circularly polarized photodetectors with a maximum anisotropy factor of 0.22, the responsivity of 1.6 A W−1, and detectivity of 2.17 × 1013 Jones. In addition, flexible circularly polarized photodetectors with extremely high mechanical stability are also realized originating from the polymer‐like behavior of cross‐linked chiral perovskite single‐crystal films. This study opens up new avenues to further enhance the performance and stability of portable and wearable devices based on chiral perovskites. [ABSTRACT FROM AUTHOR]