Afterglow Luminescence in Wet-Chemically Synthesized Inorganic Materials: Ultra-Long Room Temperature Phosphorescence Instead of Persistent Luminescence

Wet-chemically synthesized amorphous yttrium aluminum-borates (a-YAB) exhibit intense visible photoluminescence (PL). Preliminary investigations revealed a correlation of PL with the presence of carbon-related impurities; however, their exact nature is still under investigation. These powders also exhibit afterglow luminescence that lasts for several seconds at room-temperature (RT). A comparison with persistent phosphors and phosphorescent dye revealed that the afterglow in a-YAB is a phosphorescence phenomenon and not the persistence luminescence, which is more common in inorganic solids. The unusual RT phosphorescence in a-YAB could be achieved due to triplet-state stabilization of trapped luminescent organic moieties in glassy matrix. This is indeed an important step forward in understanding the complex luminescence mechanism in such promising wet-chemically synthesized functional materials. Moreover, phosphorescence is detectable for over 10 s at RT, suggesting rigid glassy inorganic matrix is more efficient in preserving phosphorescence at elevated temperatures, opening the path for several attractive applications including time-resolved bioimaging and thermometry.