Cation Design and Pressure Aging of 0D Metal Halide toward Enhanced Photoluminescence from Multiple Emission Centers

Abstract 0D hybrid metal halides (HMHs), featuring isolated building blocks, have emerged as competitive multifunctional materials with distinct photoluminescence properties. However, precisely controlling the emission features of different moieties remains a significant challenge within these materials. Herein, leveraging the irreversible pressure‐induced emission enhancement (PIEE) of PMABr (PMA + = C 6 H 5 CH 2 NH 3 + ), PMA + is applied to construct the cationic matrix of 0D HMH, (PMA) 2 SbBr 5 . The pyramidal geometry of [SbBr 5 ] 2− offers sufficient flexibility for structural and property manipulation. With increasing pressure, basically nonluminous (PMA) 2 SbBr 5 exhibits enhanced multiple emissions, originating from both organic and inorganic moieties. The pyramidal contraction and distortion accelerate exciton trapping with an increased binding energy, thereby enhancing the self‐trapped exciton emission upon compression. Simultaneously, external force induces cationic planarization and rigidity, restricting molecular motion and suppressing nonradiative pathways to promote organic emission. Notably, (PMA) 2 SbBr 5 exhibits irreversible emission enhancement after pressure release (pressure aging), which is associated with structural modifications including residual pyramidal distortion, cationic planarization, and disrupted intermolecular interactions. This study not only provides valuable insights into the emission mechanisms of 0D HMHs, but also presents a potential approach for their further functionalization for practical applications, such as pressure sensors and force‐sensitive intelligent materials.