Dynamic Phosphorescence Behavior of Carbene‐Metal‐Amide Complexes from the Perspective of Excited State Modulation

Carbene‐metal‐amide (CMA) complexes have diverse applications in luminescence, imaging and sensing. In this study, we designed and synthesized a series of CMA complexes, which were subsequently doped into a PMMA host. These materials demonstrate light‐induced dynamic phosphorescence, attributed to their long intrinsic triplet state lifetime (τP,int, in the μs‐ms scale), high intersystem crossing (ISC) rate constant (kISC, up to 107 s‐1), and bright phosphorescence. The extended τP,int, and elevated kISC facilitate efficient sensitization of singlet oxygen (1O2) under light irradiation, which is rapidly consumed by the host material, creating a localized anaerobic environment conducive to bright phosphorescence emission. The Sn‐T1 process exhibits a large spin‐orbital coupling matrix element (SOCME) value, while the SOCME value between T1 and S0 is comparatively smaller, resulting in a large kISC and long τP,int, Computational results indicate that the hole‐electron configuration in the lowest triplet state exhibits low contributions from gold. Based on the dynamic phosphorescence properties, an encryption material capable of achieving a "burn after reading" effect was developed. This work illustrates that those phosphorescent emitters with minimal heavy atom contribution can produce dynamic phosphorescent phenomena, providing a novel strategy for designing stimuli‐responsive phosphorescent materials.