New function of the Yb ion as an efficient emitter of persistent luminescence in the short-wave infrared.

The trivalent ytterbium (Yb) ion has been extensively used as an emitter in short-wave infrared (SWIR) lasers, a sensitizer to activate other lanthanide ions for up-conversion luminescence, and a spectral converter in Ln-Yb doubly doped quantum cutting phosphors. Here we report a new function of the Yb ion-as an efficient emitting center for SWIR persistent luminescence. We have developed the first real SWIR persistent phosphor, MgGeO:Yb, which exhibits very-long persistent luminescence at around 1000 nm for longer than 100 h.