Chirality-Mediated\n1D-to-2D Phase Transition in Hybrid\nLead Halide Perovskites

Dimensionality engineering plays a pivotal role in optimizing\nthe\nperformance, ensuring long-term stability, and expanding the versatile\napplications of lead halide perovskites (LHPs). Currently, the manipulation\nof LHP dimensions primarily occurs during the synthesis stage, a procedure\nhampered by constraints, including synthetic complexity and irreversibility.\nThis investigation successfully achieved a transition from one-dimensional\n(1D) to two-dimensional (2D) structures in chiral LHPs by applying\nhydrostatic pressure. Remarkably, this pressure-induced transition\nin dimensionality is absent in the racemic analogue due to the staggered\narrangement of inorganic chains and the elevated steric hindrance\nposed by the organic cations. Notably, the hydrogen bonding between\norganic cations and the inorganic framework adopts a symmetrical arrangement\nin the racemic system but a helical configuration along the 1D chain\ndirection in the chiral counterparts. This distinct helical arrangement\ninduces a consequential distortion in the inorganic moiety, resulting\nin the emergence of a spin-polarized Rashba–Dresselhaus texture\nthat explains the chirality’s electronic spin origin. Furthermore,\nboth experimental and density functional theory calculation results\ndemonstrate that the 1D-to-2D phase transition in chiral halide perovskites\ncan induce significant modifications in the electronic structures\nand associated optical emissions. In summary, the findings unveil\nnovel avenues for manipulating optoelectronic properties in chiral\nperovskites through dimensionality engineering.