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 (covalent 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.