Color-tunable and high-quantum-yield afterglow of carbon dots by covalent fixation

Because of the difficulties in populating and stabilizing the high energy triplet excited states, achieving violet organic afterglow at ambient conditions is still a formidable challenge. In this work, we propose an efficient strategy to activate violet and deep-blue afterglow of high energy triplet excited state by in situ embedding of carbon dots (CDs) into cyanuric acid crystals (CA) (named CDs@CA). The formation of covalent bonds in CDs@CA were found crucial in activating the afterglow with lifetime and phosphorescence quantum yields up to 1.80 s and 39%, respectively. Furthermore, the relationship between luminescence and copolymerization (co-valent bonding) of CDs@CA were explored, which provides evidence for the regularity of multiple luminescent centers. A light-stimulated response of CDs@CA was found useful for applications in advanced anti -counterfeiting. These results provide a foundation for designing highly efficient violet and deep-blue organic afterglow materials with potential applications in the fields of bioimaging, anticounterfeiting, and optoelectronic devices.