Metal Coordination‐Mediated Organic Room‐Temperature Phosphorescence: Toward High‐Efficiency Ultralong Emission via Nonradiative Channel Constriction

Abstract Metal–organic room‐temperature phosphorescence (RTP) materials have garnered significant attention due to their unique optical properties and broad applicability. However, achieving dynamic manipulation of phosphorescence within a single material, alongside the simultaneous enhancement of both phosphorescence quantum yield and ultralong lifetime, remains a substantial challenge. Herein, two metal–organic complexes, LMHU‐1 and LMHU‐2 , are successfully constructed, exhibiting pronounced temperature‐dependent dynamic phosphorescence. Remarkably, thermal modulation facilitates a reversible emission transition from blue long‐persistent luminescence at cryogenic conditions to green phosphorescence at ambient temperatures, with visible phosphorescence persistence exceeding 104°C. Furthermore, metal coordination drastically suppresses non‐radiative decay pathways within the ligands, thereby substantially elevating phosphorescence efficiency. Specifically, the non‐radiative decay rate constant ( k nr P ) is suppressed by up to 514.0‐fold, while the phosphorescence lifetime ( τ P ) and quantum yield ( Φ P ) are enhanced by up to 508.12‐fold and 1.93‐fold, respectively. Theoretical calculations elucidate that the phosphorescence originates from robust ligand‐centered triplet excited states. Leveraging these tunable phosphorescence characteristics, the materials demonstrate significant potential for information encryption/decryption and optical anti‐counterfeiting applications. This work not only provides a novel strategy to address the concurrent enhancement of Φ P and τ P , but also offers a viable blueprint for the application of metal–organic materials featuring dynamic ultralong RTP in information security.