Urea‐Formaldehyde Resin Confined Silicon Nanodots Composites: High‐Performance and Ultralong Persistent Luminescence for Dynamic AI Information Encryption

Persistent luminescence materials typically encounter an intrinsic trade-off between high phosphorescence quantum yield (PhQY) and ultralong phosphorescence lifetime. To overcome this limitation, we propose a strategy that immobilizes silicon nanodots (SiNDs) within a dual-functional composite matrix. The SiNDs efficiently generate abundant triplet excitons through intersystem crossing processes and simultaneously exhibit high PhQYs. Importantly, the urea-paraformaldehyde-derived matrix provides both the spatial confinement of molten urea and the extensive hydrogen-bonding network of the urea-formaldehyde resin. This synergistic configuration effectively immobilizes triplet excitons and suppresses nonradiative decay pathways. As a result, the material exhibits a remarkable PhQY of 81.04% together with an ultralong afterglow lifetime of 3.44 s. Furthermore, the energy transfer strategy further extends the persistent afterglow into the deep-red region (702 nm). Leveraging the tunable afterglow colors and time-resolved luminescent characteristics, an artificial intelligence-assisted information encryption system was successfully developed. This work demonstrates that integrating SiNDs with a dual-characteristic matrix provides a promising approach to concurrently achieving high PhQYs and ultralong lifetimes, thereby broadening the application scope of ultralong-afterglow materials and guiding the rational design of next-generation persistent luminescence materials.