Enhanced Afterglow Performance in Ba ₅ Si _8‐x A _x O ₂₁ : Eu ²⁺ (A = Al ³⁺ and B ³⁺ ) Phosphors via Oxygen Vacancy Tuning

ABSTRACT Silicate‐based persistent luminescence (PersL) materials have shown significant applications in energy‐saving lighting and instrument displays due to their excellent water resistance and physicochemical stability. Nevertheless, achieving afterglow performance comparable to the benchmark SrAl 2 O 4 : Eu 2+ , Dy 3+ remains challenging. In this study, we report a significant enhancement of Eu 2+ PersL in Ba 5 Si 8‐x A x O 21 : Eu 2+ (A = Al 3+ and B 3+ ) via aliovalent substitution at the Si 4+ site. The afterglow intensity is boosted by approximately 2‐fold and 100‐fold for Al 3+ and B 3+ doping, respectively. To get insight into the relationship between structure and afterglow performance, the site occupations of Eu 2+ , trap distribution and afterglow kinetics were systematically investigated. The enhanced Eu 2+ afterglow is mainly attributed to an increased concentration of oxygen vacancies rather than the changes of band structure and trap depth. Thermally assisted tunneling of Eu 2+ afterglow is verified by multi‐Becquerel functions analysis. The work provides an efficient strategy to improve afterglow performance of Eu 2+ doped silicate phosphors through the controlled engineering of oxygen vacancies.