A Pyrolysis‐Assisted Strategy for High‐Temperature Resistant Afterglow Materials Through Defect‐Mediated Emission Mechanisms

ABSTRACT Achieving high‐temperature‐resistant afterglow is highly desirable yet challenging, primarily due to exciton deactivation at elevated temperatures. In this work, a co‐pyrolysis strategy was proposed to achieve such afterglow by modulating the emission dynamics of organic molecules through introducing of structural defects. These defects facilitate exciton transfer to guest molecules, extending and balancing the lifetimes of both thermally activated delayed fluorescence and phosphorescence processes. The structural defects also promote thermoluminescence, wherein elevated temperatures trigger the release of trapped electrons to the guest molecules, thereby contributing significantly to the exceptional high‐temperature afterglow stability. Additionally, the pyrolysis process generates ammelide, which protects excitons from deactivation. These synergistic effects yield afterglow materials exhibiting a photoluminescence quantum yield of 59.9% and an emission lifetime of 3.5 s. Remarkably, intense afterglow emission persists from 25 to 150°C with negligible changes in emission color, intensity, and decay kinetics. These findings provide valuable insights for modulating the emission dynamics of afterglow materials, suggesting promising applications in information security, biomedical diagnosis, and chemical sensing.