Time-Dependent Room-Temperature Afterglow of Carbon Dots Constructed by Trap-Induced Multiemission Centers

Traps, due to the ability to capture, store, and release charge carriers, have attracted significant attention in the construction of long afterglow materials. In this study, a one-step in situ calcination strategy was employed to fabricate carbon dot (CD)-based composites, and the traps were designed as one of the emission centers within the composite system. Upon removal of ultraviolet light, the materials showed a time-dependent afterglow color (TDAC), with the luminescent color gradually changing from orange to green. The study indicates that the dynamic afterglow results from the energy transfer from traps to the surface triplet state of the CDs. In addition, CDs generated during the in situ calcination process serve as dopants, increasing the number of original traps and facilitating the formation of new ones. Based on the TDAC characteristics, we demonstrate the applications in anti-counterfeiting and information encryption. This strategy offers new insights into the development of multicolor afterglow materials.