New Mechanistic Insights into Persistent Luminescence in Rare-Earth Co-Doped Phosphate Phosphors

Persistent phosphors, which exhibit prolonged luminescence after the cessation of excitation, hold considerable potential for a wide range of applications. However, the fundamental mechanisms governing persistent luminescence (PersL) are not yet fully understood. In this study, the archetypal YPO 4 :Ce 3+ /Dy 3+ system is investigated to provide new insights into the PersL mechanism. Under X-ray irradiation, the co-doped phosphor exhibits the characteristic emissions of both Ce 3+ (335, 356 nm) and Dy 3+ (486, 575 nm). Efficient energy transfer from Ce 3+ to Dy 3+ is confirmed, indicating their close spatial proximity. Remarkably, co-doping synergistically enhances the PersL performance of both ions, with their PersL durations being significantly prolonged compared to their singly doped counterparts. Further analysis suggests that Ce 3+ stabilizes the Dy 3+ luminescent center, a phenomenon that is attributed to the formation of associated Ce 3+ -Dy 3+ complexes. These findings support a model where such complexes act as effective charge trapping centers, enhancing PersL. Building on these tunable properties, a potential application in dynamic anti-counterfeiting is demonstrated. This work deepens the understanding of PersL mechanisms in co-doped phosphors and offers a strategy for the rational design of advanced luminescent materials.