Pressure Regulate Inversion Symmetry Breaking in 1D Chiral Organic–Inorganic Lead Halide Perovskites toward High Photoluminescence and Large Spin‐Splitting

Abstract Chiral organic–inorganic lead halide perovskites (chiral OILHPs) have potential application value in spintronics due to their inherent inversion symmetry breaking (ISB) and strong spin‐orbit coupling (SOC) effects. However, the dependence on structural dimensionality has led to some photophysical properties of 1D chiral OILHPs being barely satisfactory, such as low photoluminescence quantum yield (PLQY) and weak spin‐splitting. This paper utilizes high‐pressure as a regulatory tool in 1D R‐AMP(DMA)PbBr 5 , acquiring the following findings: i) The PLQY exceeds 85.6% (5 GPa) by optimizing the degree of ISB, which is currently the highest PLQY value in 1D chiral OILHPs. ii) The spin‐splitting energy increases from 2.0 meV (1 atm) to 29.8 meV (10 GPa), surpassing the room temperature thermal energy benchmark of 25.9 meV. High‐pressure structural characterization and second‐harmonic generation (SHG) reveal a sharp increase in ISB caused by the phase transition. Further TBSOC calculations indicate that the increased degeneracy of Pb‐6p orbitals breaks the weak SOC effect in 1D chiral OILHPs. This work not only overcomes the limitations of low PLQY and weak spin‐splitting in 1D chiral OILHPs through high‐pressure but also reveals the ISB origin of high PLQY and giant spin‐splitting, providing insights for the tunable design of high‐performance spintronic materials.