Phase-Dependent Control of Trap Depth and Persistent Luminescence in Strontium Aluminate Phosphors

Persistent luminescent (PersL) materials have garnered significant attention for applications in visualization, signaling, bioimaging, and anti-counterfeiting due to their long-lasting emission after pre-excitation. However, achieving both extended emission durations and stable luminescence remains challenging. In this study, we propose two previously lab-synthesized ceramics: Sr4Al14O25:Eu²⁺, Dy³⁺, B³⁺ (blue-emitting@490 nm, SAO-B) and SrAl2O4: Eu²⁺, Dy³⁺, B³⁺ (green-emitting@520 nm, SAO-G) belonging to strontium aluminate phosphors. This work demonstrates a comprehensive experimental approach involving detailed thermoluminescence (TL) and PersL characterizations. Under various excitation sources (UV and visible light), we identified that SAO-B exhibits deeper traps and longer decay times, whereas SAO-G shows stronger initial emission intensity. Furthermore, the video records two novel 'temperature-resolved' and 'time-resolved' dynamic anti-counterfeiting technologies within a wide time scale from a few seconds to minutes. The provided methodology serves as a valuable reference for researchers aiming to optimize persistent phosphors for security, safety lighting, and dynamic display applications.