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

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. This work provided a facile strategy for achieving water-soluble polymeric afterglow materials with ultralong lifetime, wide color-tunability and persistent near-infrared luminescence via constructing three/four-component energy transfer systems that are capable of occurring non-traditional phosphorescence resonance energy transfer and two-step energy transfer cascade.image