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.