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)( R -4)PbBr 4 and (BA)( S -4)PbBr 4 [ R -4/ S -4 = ( R )/( S )-(+)-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 ( Cc → C 2 → C 2/ c ) 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.