Matrix-Mediated Color-Tunable Ultralong Organic Room Temperature Phosphorescence of 7H-Benzo[c]carbazole Derivatives

Building on the recent systematic research on 1H- benzo[f]indole (Bd), an important advancement in constructing ultralong organic room temperature (UORTP) materials with a universal strategy via a readily obtained unit (7H-Benzo[c]carbazole, BCz) is proposed in this work. Pure powders of BCz and its derivatives merely exhibit blue fluorescence at ambient condition. However, when BCz and its derivatives are dispersed into polymer or powder matrixes, strong photo-activated green UORTP can be observed from their doped systems at room temperature. Moreover, the UORTP color can be tuned between green and yellow depending on the matrix. The ultralong phosphorescence originates from the generation of charge-separated states via radicals. The matrixes play a key role in both stabilizing charge-separated states and controlling UORTP color. More interestingly, when using polymethyl methacrylate as matrix, the doped films achieve stronger photo-activated ultralong phosphorescence underwater than in air at room temperature. Compared with Bd, BCz achieves better performance not only in ultralong phosphorescence properties but also in practical applications. This work gains a deeper insight into the mechanism of UORTP and paves a new approach to applying organic phosphorescent materials to underwater coating and imaging.