Luminescence characterization of a new long afterglow phosphor of single Ti-doped Y2O2S

A new rare-earth free phosphor Y2O2S:Ti with long afterglow was synthesized by solid-state reaction. A strong and broad emission band, which is suggested to come from the recombination of trapped electrons in the donating level and holes in the accepting level, was observed under 382 nm irradiation with a peak at 565 nm. The luminescence intensity and afterglow of the phosphors are enhanced with increase of doped Ti concentration. Furthermore, the best yellow long afterglow for present materials was found in the sample with 9 mol% doping Ti content, and its afterglow can last over 5 h with recognizable intensity level (0.32 mcd/m2) after the removal of the excitation light.