Dynamics 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 accompanied with the unclear underlying mechanisms lead to weak luminescence responses of PersL materials to excitation fields, which has almost hindered all related applications. Herein, a series of Sr₃Lu₂Ge₃O₁₂:Ln (Ln = Tb, Ti, Pr, and Dy) phosphors were designed and developed. The effects of doped ions on photoluminescence and the kinetic processes of fluorescence responses to photo/thermal excitation fields were systematically studied. The multimodal luminescence response mechanism of trap doublets to excitation fields were deeply analysed by the TL curves and rate equation. The results show that the roomtemperature carrier storage efficiency and duration are positively correlated with trap depth. A trap depth ≥1.0 eV can effectively suppress the room-temperature PersL process, which is beneficial to the stability requirements of high-density optical storage. This study provides design concepts for the controlled luminescent characteristics in deep-trap PersL materials and their applications in information storage.