Dimensional engineering in chiral layered hybrid perovskites for high-anisotropy self-powered circularly polarized...

Chiral perovskites have emerged as a highly promising family of materials for circularly polarized light (CPL) detection, owing to their unique combination of structural chirality and remarkable optoelectronic performance. However, breaking the linear scaling law between chiroptical activity and intrinsic conductivity with dimensionality remains a substantial challenge toward high-performance CPL detection. Herein, through dimensional engineering involving the incorporation of a large cage cation and a chiral bifunctional bulky cation, a series of chiral layered hybrid perovskites (R/S-BrBA)₂EA _n-1Pb _n Br_3n+1 (n = 1 to 3; R/S-BrBA⁺: 3-amino-1-bromobutanium; EA⁺: ethylammonium) has been successfully constructed. By incorporating oversized EA⁺ within the layered perovskite lattices, two new pairs of multilayered hybrid perovskites (R/S-BrBA)₂EAPb₂Br₇ (2R/S) and (R/S-BrBA)₂EA₂Pb₃Br₁₀ (3R/S) have been synthesized, which exhibit remarkable semiconducting properties, including small optical absorption edges (2.79 and 2.69 eV) and high photoconductive on/off ratio (>10² and 10³). Strikingly, cooperatively driven by the large cation-induced lattice expansion and bifunctional cation-introduced halogen⋯halogen interaction, the chirality transfer from the organic to inorganic sublattices increases, and the chiroptical activity with an asymmetric factor was enhanced by 5.7 times as the n value increased, breaking the linear scaling law. Benefiting from the dimensional engineering, exceptional self-powered CPL detection with an anisotropy factor (g _Iph) of up to 0.278 has been achieved in a photoelectric device fabricated with 3R single crystals. This study provides a pathway for the development of chiral perovskites that integrate high chiroptical activity and remarkable intrinsic conductivity, thereby enabling high-anisotropy self-powered CPL detection.