Colorful, time-dependent carbon dot-based afterglow with ultralong lifetime

Metal-free afterglow materials have brought about widespread attention due to application advantages. Nevertheless, it is an attractive but formidable challenge to achieve long-persistent afterglow materials with high quantum yield (QY) at ambient conditions. Particularly, those with tunable afterglow are very rare. Herein, an economical strategy is proposed to construct a series of multi-color (cyan, green and orange) afterglow materials via one-step melting (within 5-10 min) of boric acid (BA) with unconventional precursors. The highly rigid framework, B C bond and hydrogen bond interactions can efficiently inhibit non-radiative deactivation by locking the triplet excitons in carbon dots (CDs) clusters. 66.13% high QY and 1.74 s long lifetime have been achieved simultaneously, as well as the afterglow can be observed by naked eyes for ~ 26 s. According to the adjustment of the precursor structure, dynamic afterglow color-changing (from orange, yellow, white to cyan) material was successfully realized. These excellent features allow them to be more applicable in time-resolved information security. In brief, this work provides a simple, flexible and effective strategy to construct highly efficient afterglow materials, and further facilitates their optical regulation and various potential applications.