Phosphorescent materials with time-dependent phosphorescent color (TDPC) output have significant potential for applications in advanced optical information encryption. However, the effective construction of TDPC composites compatible with multiple phosphorescent emission centers to achieve wider phosphorescent colors evolving over time in a single material system remains a huge challenge. Here, ultra-wide TDPC composites evolving with time were firstly realized in a single system by exploiting the synergistic effect of the doubly confined structure. Utilizing organosilanes to pretreat the reactive precursor, combined with a boric acid (BA) matrix, the composite (Si-CDs@B2O3) was prepared by direct calcination. Our results reveal that the Si-CDs@B2O3 composite has significant ultra-wide TDPC properties, with the phosphorescent emission shifting from red to orange, yellow, green, and cyan blue. Characterization analysis reveals the important role of organosilanes in achieving the ultra-wide TDPC property, and also elaborates that the red phosphorescence and blue phosphorescence originate from the interaction of C=O on the surface of CDs with BA matrix and the intrinsic blue phosphorescence emitted from B-O in the BA matrix, respectively. The distinctive dynamic room-temperature phosphorescence properties of the Si-CDs@B2O3 composite were leveraged to develop a strategy for its use in information encryption on a precise time scale.
