The codoping of Bi3+ to enhance the long afterglow performance of LiTaO3:Er3+

Abstract

Long afterglow phosphors have garnered significant attention for their ability to emit light long after excitation ceases. Afterglow emission relies on metastable trap levels within the bandgap of the host materials. Effective trap engineering strategies to optimize traps are critical in determining the afterglow performance. In this study, we investigate the codoping of Bi³⁺ and Er³⁺ into LiTaO₃ to enhance afterglow performance. Through high-temperature solid-state synthesis, a series of LiTaO₃:x%Bi³⁺, y%Er³⁺ (x = 0 or 0.5%, y = 0.1–4.0%) samples were prepared successfully. Structural characterization confirmed the successful incorporation of Bi³⁺ and Er³⁺ into the Li⁺ sites without disrupting the host lattice. Photoluminescence studies revealed that Bi³⁺ codoping significantly enhances the green emission of Er³⁺, with optimal performance achieved at 1.0% Er³⁺ doping. Thermoluminescence (TL) analysis demonstrated the presence of traps with the depth of 0.748 eV, enabling prolonged afterglow emission at room temperature. The afterglow mechanism involves charge carrier storage in traps under UV excitation, followed by thermal release and recombination at luminescent centers, facilitated by energy transfer from Bi³⁺ to Er³⁺. This work provides a strategy for designing a long afterglow phosphor through controlled codoping, offering insights into trap engineering and energy transfer processes in perovskite-based luminescent materials.