Up-conversion charging of a Tb³⁺-activated garnet phosphor

Studies on the up-conversion charging of persistent phosphors are of great academic and practical significance. To date, up-conversion charging designs have been achieved in Cr³⁺, Mn²⁺ and Pr³⁺-activated phosphors. We herein report, for the first time, an up-conversion charging process in the Tb³⁺-activated garnet phosphor, Gd₃Ga₅O₁₂:Tb³⁺, using a 488 nm laser as the excitation source. The delocalized 4f⁷5d state of Tb³⁺ is excited by absorbing two excitation photons, followed by the charging of the phosphor. Moreover, spectroscopic investigations reveal that an energy-transfer mechanism dominates the up-conversion excitation. This work provides an up-conversion strategy for charging Tb³⁺-activated phosphors, paving the way toward expanding the scope of persistent phosphors with up-conversion chargeability.