Persistent Luminescence Analysis in the Frequency Domain

Abstract Frequency‐domain techniques offer a powerful means to disentangle overlapping physical processes with distinct characteristic timescales—yet remain underexplored in the context of complex photoluminescent materials. Here, frequency‐domain analysis is applied to persistent luminescence (PersL) materials, which exhibit long‐lasting emission following excitation due to charge trapping and detrapping processes spanning wide temporal ranges. Using SrAl ₂ O ₄ :Eu ² ⁺,Dy ³ ⁺ (SAO:Eu,Dy) as a model system, a general framework is developed for frequency‐domain characterization of PersL and reports, for the first time, a direct measurement of the trapping rate in such a material. This approach also enables quantitative assessment of trapping probability, efficiency, and overall PersL performance. This work opens a new pathway for rational optimization of afterglow materials based on mechanistic insights beyond conventional time‐domain approaches.