Near-infrared afterglow enhancement of ZnGa 2 O 4 :Cr 3+ via regulating trap distribution guided by the VRBE diagram.

Lanthanide ions are commonly used as co-dopant ions for trap regulation in afterglow phosphors. However, rationally designing trap distribution to improve the afterglow performance remains challenging. Herein, the vacuum referred binding energy (VRBE) diagram was constructed to aid in the search for effective lanthanide ions to improve the near-infrared afterglow properties of ZnGa 2 O 4 :Cr 3+ . The constructed VRBE diagram indicates that Ln 3+ (Ln = Sm, Yb, Tb) ions can create traps in ZnGa 2 O 4 , which is confirmed by the luminescence characterization. Results show that doping with Ln 3+ (Ln = Sm, Yb, Tb) ions can significantly improve the afterglow intensity and duration of the phosphor due to the increased shallow trap density and trap depth. Among these samples, the Sm 3+ -doped sample exhibits the best afterglow properties. The afterglow enhancement mechanism by Ln 3+ doping is discussed in detail. This work not only presents the lanthanide ions that can be used to regulate the trap distribution of ZnGa 2 O 4 :Cr 3+ phosphors, but also provides new insights for the design of new afterglow phosphors with practical application value.