Pressure‐Induced Distinct Conformational Evolution of Organic Spacer Cations in 2D Perovskites

The conformation and arrangement of organic spacer cations in 2D Ruddlesden‐Popper (RP) perovskites have a significant effect on the structure of inorganic framework and photoluminescence (PL) properties. However, how conformational changes of organic cations affect the PL properties in 2D RP perovskites remains unclear. Herein, we investigate the conformational evolution of organic cations by regulating hydrogen bonding effect on the inorganic [PbBr x I 4‐x ] 4− framework with different proportions of halogens under pressure. The results reveal that the PEA organic cation within inorganic framework buffers the pressure through conformational transformation under compression. Notably, the pressure threshold for PEA molecular conformational transformation and deformation resistance of inorganic framework gradually decreases when the proportion of iodide component increases in (PEA) 2 PbBr x I 4‐x perovskites. This work provides a new understanding of the intrinsic structure‐property relationships between conformational evolution of organic cations and their regulation PL properties in 2D perovskites.