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

ABSTRACT 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.