Gd³⁺-activated narrowband ultraviolet-B persistent luminescence through persistent energy transfer

This work reports the realization of Gd3+ persistent luminescence in the narrowband ultraviolet-B (NB-UVB; 310-313 nm) through persistent energy transfer from a sensitizer of Pr3+, Pb2+ or Bi3+. We propose a general design concept to develop Gd3+-activated NB-UVB persistent phosphors from Pr3+-, Pb2+- or Bi3+-activated ultraviolet-C (200-280 nm) or ultraviolet-B (280-315 nm) persistent phosphors, leading to the discovery of ten Gd3+ NB-UVB persistent phosphors such as Sr3Gd2Si6O18:Pr3+, Sr3Gd2Si6O18:Pb2+ and Y2GdAl2Ga3O12:Bi3+ as well as five ultraviolet-B persistent phosphors such as Y3Al2Ga3O12:Pr3+, Sr3Y2Si6O18:Pb2+ and Y3Al2Ga3O12:Bi3+. The persistent energy transfer from the sensitizers to Gd3+ is very efficient and the Gd3+ NB-UVB afterglow can last for more than 10 hours. This study expands the persistent luminescence research to the NB-UVB as well as the broader ultraviolet-B spectral regions. The NB-UVB persistent phosphors may act as self-sustained glowing NB-UVB radiation sources for dermatological therapy.