A Facile Strategy for Achieving Polymeric Afterglow Materials with Wide Color‐Tunability and Persistent Near‐Infrared Luminescence

Abstract Polymer‐based room‐temperature phosphorescence (RTP) materials show promising applications in anti‐counterfeiting. To further realize multiscale and/or multimodal anti‐counterfeiting, it is highly desirable to develop polymeric afterglow materials with multiple security features. Herein, a facile strategy is presented to endow polymeric afterglow materials with ultralong lifetime, wide color‐tunability, persistent near‐infrared (NIR) luminescence, and good water solubility via constructing non‐traditional phosphorescence resonance energy transfer (PRET) and two‐step sequential resonance energy transfer systems. Specifically, the 1‐bromocarbazole derivatives with ultralong blue‐color RTP property act as the energy donor while traditional dyes with red/NIR luminescence act as the energy acceptor. By simply regulating the doping composition and concentration of these non‐traditional energy transfer systems, persistent and multicolor organic afterglow covering from the visible to NIR region is successfully realized. Notably, compared to the single‐step PRET, the two‐step sequential resonance energy transfer has the unique advantages of higher transfer efficiency of triplet excitons from the initial donor, a wider range of color‐tunability mediated by the intermediary acceptor, and enhanced delayed fluorescence efficiency of the final acceptor. Finally, these water‐soluble polymeric afterglow materials with ultralong lifetime, wide color‐tunability, and persistent NIR luminescence show great potential applications in advanced anti‐counterfeiting and information security technologies.