Full‐Color Tunable Time‐Dependent Room‐Temperature Phosphorescence from Self‐Protective Carbonized Polymer Dots

Achieving full-color time-dependent tunable phosphorescence (TDTP) in pure organic materials remains a significant challenge due to the nonradiative transition and modulation puzzle of triplet states. Herein, full-color TDTP has been realized in self-protective carbonized polymer dots (CPDs) under ambient conditions using a self-doping strategy. These CPDs are generated with dual emission centers of the high-energy N-related triplet state and the low-energy surface oxide triplet state, which are responsible for the slow-decaying blue afterglow (453 nm) and the fast-decaying green to red afterglow (513-609 nm), respectively. These luminescent centers can be activated simultaneously upon CPD aggregation due to the generated rigid networks by intra/intermolecular hydrogen-band interactions. The detailed experimental characterization and theoretical calculation confirm that the red-shifted afterglow color is attributed to a gradual reduction of their energy levels with the increasing surface C═O content and aggregation degree of CPDs. Thus, these matrix-free CPDs exhibit dynamic TDTP colors over the entire visible spectrum in the solid state after turning off 365 nm UV light. Based on their unusual phosphorescent properties and excellent photostability, these CPDs have been tested for various applications such as multidimensional dynamic information encryption and anti-counterfeiting, as well as time-delayed light-emitting diodes (LEDs).