Overcoming Chiral‐Optoelectronic Trade‐Off in Two‐Dimensional Halide Perovskites for Circularly Polarized Photodetectors

Two‐dimensional (2D) perovskites hold great promise for optoelectronic devices due to the flexible tunability of chiral optical activity and optoelectronic properties. However, the trade‐off between strong chiral effect and efficient charge transport restricts their development in high‐performance circularly polarized light (CPL) detection. In this work, a tailored achiral‐chiral cation mixing strategy is proposed to improve the intermolecular forces and out‐of‐plane octahedral tilt in the chiral perovskite, which effectively promotes chirality transfer and van der Waals forces tuned vertical growth. Further, a chiral 2D perovskite‐based CPL photodetector is constructed with balanced high absorption anisotropy ( g abs ) and photocurrent anisotropy ( g Iph ). Compared with materials obtained with pure chiral cations, the maximum g abs of this chiral 2D perovskite increased by 7.33 times. The enhanced chiroptical activity and in‐plane transport in vertically oriented chiral 2D perovskites endowed the self‐powered CPL device with outstanding performance and a record g Iph of 0.72. This work opens a reasonable paradigm of chiral 2D perovskite photodetectors in information encryption.