Enhanced afterglow behavior of a new Eu²⁺: Sr₂Al₂SiO₇ green phosphor co-doped with different cations Nd³⁺, Dy³⁺, Ho³⁺, Tm³⁺ and Yb³⁺

Eu²⁺ and Ln³⁺ (Ln³⁺ = Nd³⁺, Dy³⁺, Ho³⁺, Tm³⁺, Yb³⁺) co-doped Sr₂Al₂SiO₇ green-phosphors were synthesized via high temperature solid state method. The XRD analysis proved that the obtained phosphors are all pure-phased. To investigate the luminescent properties, the analysis of fluorescence, afterglow luminescence, photo-stimulated luminescence and diffuse reflection spectrum were conducted. It is evident that the central positions of excitation and emission spectra remained unchanged. However, the intensity and decay time of the afterglow and photo-stimulated luminescence of Eu²⁺ were tunable through doping with various Ln³⁺ ions. Among them, Eu²⁺ and Tm³⁺ co-doped Sr₂Al₂SiO₇ exhibits excellent photo-stimulated luminescence properties. Moreover, the results from thermoluminescence (TL) measurements suggest that the introduction of Tm³⁺ doping induces deeper traps. Additionally, afterglow decay and TL curves were assessed, highlighting the exceptional phosphorescent properties exhibited by the present phosphors.