Excitation- & concentration-dependent color-tunable ultra-long phosphorescence of isophthalonitriles doped polymers

Room-temperature phosphorescence (RTP) from organic materials have been widely studied especially in the recent decades, however, the majority can only release a single-color phosphorescence after removal of the excitation. Achieving color-tunable RTP from pure organic materials is attractive but still challenging. Herein, we report a family of color-tunable RTP materials by doping isophthalonitriles into polymers. The doped polymers not only possess adjustable phosphorescence from blue to green by controlling the excitation wavelength and the doping concentration, but also exhibit ultralong lifetimes (1048 ms for green-phosphorescence and 872 ms for blue-phosphorescence) and afterglow times (>10 s). Multi-level encryption was demonstrated by utilizing the multicolored phosphorescence realized through alternation of the excitation wavelength and adoption of different concentration doped polymers. Considering all the involved components are commercially available with low-cost, such a color-tunable and long afterglow system should be potential toward a broad field of advanced anti-counterfeiting applications.