Dynamic processes of multimodal luminescence in long persistent phosphors

Abstract

Deep-trap long persistent luminescence (PersL) materials exhibit significant advantages in optical information storage due to their unique carrier trapping–release dynamics. However, the lack of effective trap control methods, coupled with the unclear underlying mechanisms, leads to weak luminescence responses of PersL materials to excitation fields, which has seriously hindered all related applications. Herein, we designed and developed a series of Sr₃Lu₂Ge₃O₁₂:M (M = Tb, Ti, Pr, and Dy) phosphors. We systematically investigated the effects of doped ions on the photoluminescence properties and the kinetic processes of fluorescence responses to photo-/thermal excitation fields. Furthermore, the multimodal luminescence response mechanism of trap doublets to excitation fields was thoroughly analyzed using thermoluminescence curves and rate equations. The results demonstrate that the room-temperature carrier storage efficiency and duration are positively correlated with the trap depth. Notably, a trap depth of ≥1.0 eV can effectively suppress the room-temperature PersL process, which meets the stability requirements for high-density optical storage. This study provides design concepts for the controlled luminescence characteristics in deep-trap PersL materials and their application in information storage.