Giant Emission Enhancement from Hybrid Manganese Bromide Via Pressure‐Induced Band‐Edge Carrier Reconfiguration

Abstract Pressure‐induced emission enhancement (PIEE) is a novel phenomenon in contrast to conventional pressure‐induced emission quenching, and has attracted considerable attention owing to the potential application of materials with this effect as optical pressure‐sensing devices. The urgent need and significant significance lie in the design and exploration of systems that possess high‐efficiency PIEE. Here, a large PIEE in a novel zero‐dimensional (0D) hybrid manganese bromide is realized, (BPPH)₂MnBr₄·1.5CH₃CN [BPPH⁺ = bis(triphenylphosphine)iminium]. The experimental and theoretical results demonstrate that such emission enhancement is primarily attributed to the pressure‐induced reconfiguration of electronic band alignment and resultant redistribution of band‐edge excitons. Under compression, the electronic bandgap of (MnBr₄)²⁻ experiences a more rapid reduction compared to that of the organic cations. Consequently, this leads to the gradual closure of the charge transfer pathway from (MnBr₄)²⁻ to BPPH⁺. This progression results in a higher retention of excitons on (MnBr₄)²⁻, amplifying the efficiency of Mn²⁺ d–d transitions, and leading to a substantial enhancement in emission. This study not only offers fresh insights into the behavior of carrier dynamics induced by pressure in hybrid manganese halides but also presents a promising avenue for the advancement of PIEE systems.