Hour-Level and Air-Stable Organic Long-Persistent Luminescence from Organic-Inorganic Hybrid Materials

Organic long-persistent luminescence (OLPL) materials show important application prospects in bioimaging due to their low biotoxicity and the ability to eliminate the interference of background fluorescence. However, OLPL materials suffer from poor environmental stability and short afterglow times. Herein, by introducing the phosphorescent guest 2, 3-naphthalimide (NAI) into the B₂O₃ (BO) matrix using a solvent-free method in an air atmosphere, an organic-inorganic hybrid material NAI/BO is obtained, exhibiting OLPL lasting for more than 20 h, visible to the naked eye for up to 180 min. Photoluminescence and thermoluminescence spectra reveal that the OLPL originates from pure phosphorescence of NAI, and is induced by inorganic defects generated by oxygen vacancies in BO. The NAI electrons in the excited state can be captured by the defect, then detrapped through the thermal activation process, and eventually returned to the triplet state of NAI, thereby achieving OLPL emission. NAI/BO is successfully applied in vivo imaging stimulated in vitro. In addition, the universality of this strategy is verified by changing the phosphorescent guest molecules, enabling the regulation of OLPL from green to orange-red light. These results provide an important foundation for the design and development of stable OLPL materials and the practical applications in biological imaging.