Symmetry Breaking in High-Speed Synthesized Chiral Two-Dimensional Perovskite Single Crystals Enabling Polarization-Sensitive Advanced Optoelectronics

While their asymmetry dictates function, controlling non-centrosymmetry during scalable growth of chiral two-dimensional perovskites is challenging. Herein, we introduce a high-pressure hydrothermal synthesis method that enables rapid, defect-tolerant growth of chiral perovskite single crystals, i.e., (BA)(<i>R</i>-4)PbBr₄ and (BA)(<i>S</i>-4)PbBr₄ [<i>R</i>-4/<i>S</i>-4 = (<i>R</i>)/(<i>S</i>)-(+)-1-(4-bromophenyl)ethylammonium and BA = butylammonium], with an order-of-magnitude faster kinetics while maintaining high structural homogeneity and non-centrosymmetric ordering. Temperature-dependent single-crystal X-ray diffraction reveals a reversible polar-to-centrosymmetric phase transition (<i>Cc</i> → <i>C</i>2 → <i>C</i>2/<i>c</i>) mediated by thermally activated octahedral tilting and chiral-spacer-induced lattice distortion. First-principles calculations corroborate that these structural features yield asymmetric charge distributions and highly anisotropic carrier transport along the polar axis. The engineered structural asymmetry enables a remarkable linear polarization ratio (LPR ≈ 0.97) in photodetectors, facilitating advanced functionalities like polarization-resolved imaging. We provide a scalable platform for rapid synthesis of chiral perovskite crystals, establishing a robust design paradigm for high-performance, polarization-sensitive optoelectronics via targeted symmetry breaking.