Highly Circularly Polarized Light‐Sensitive Chiral One‐Dimensional Perovskites Enabled by Antisolvent Engineering

Chiral perovskites have emerged as promising next‐generation materials for polarization detection due to their excellent circularly polarized light (CPL) detection capabilities. However, they suffer from a low chiroptical response when fabricated as a polycrystalline thin film, limiting their potential range of applications. Herein, it is demonstrated that antisolvent dripping during the spin‐coating process can effectively improve the chiroptical properties of polycrystalline chiral perovskite thin films. Systematic analysis with different antisolvents reveals that the highly polar antisolvent chloroform interacts with dimethyl sulfoxide molecules via hydrogen bonding. This strong hydrogen bonding suppresses the formation of intermediate and secondary phases and accelerates the crystallization of chiral 1D perovskites, thus reducing the density of the iodine vacancies inside the perovskite thin films. The lower density of iodine vacancies also intensifies the asymmetric tilting inorganic distortion of PbI6 octahedrons, enhancing the chiroptical response of the fabricated chiral perovskite material. Photodetectors based on the chloroform‐treated chiral perovskite films achieve a remarkably high distinguishability of 0.31, outperforming previously reported photodetectors based on the chiral perovskites. The fabricated photodetectors also exhibit outstanding responsivity and detectivity with enhanced operational stability. An antisolvent dripping strategy is employed to fabricate chiral 1D (S‐MBA)PbI3 (MBA = methylbenzylamine) perovskites. The crystallization process of a perovskite and the density of its structural defects can be controlled by the choice of antisolvent. By using chloroform as the antisolvent, iodine vacancies are effectively suppressed and the inorganic framework is distorted, producing a highly circularly polarized light‐active chiral perovskite.