Alternating chiral and achiral spacers for constructing two-dimensional chiral hybrid perovskites toward circular-polarization-sensitive photodetection

The intrinsic integration of structural flexibility, chiroptical activity, and photoelectric properties endows the two-dimensional (2D) chiral hybrid perovskites (CHPs) with significant application potential in chiroptoelectronics and spintronics. However, the scarcity of suitable chiral organic ligands severely hinders their extensive construction, necessitating the development of new strategies for designing 2D CHPs. Herein, by exploiting a half substitution method, we created a pair of 2D CHPs with alternating cations in the interlayer space (ACI), (R/S-PPA)(PA)PbBr₄ (2R/2S, PPA = 1-phenylpropylamine, PA = n-pentylamine), from the achiral Ruddlesden-Popper (RP) (PA)₂PbBr₄ (1). The successful chirality transfer induces 2R/2S to crystallize in the chiral P2₁2₁2₁ space group and thus acquire appealing chiroptical activity. Consequently, the single-crystal devices of 2R exhibit good distinguishability to the left- and right-handed circularly polarized 405 nm lights with a photocurrent dissymmetric factor of 0.10 at 10 V bias. This work demonstrates an intriguing achiral RP to chiral ACI motif reconstruction in 2D halide hybrid perovskites, opening a door for expanding the family of 2D CHPs.