Novel color-tunable Ce3+/Ln3+ (Ln = Tb, Sm, Dy) co-doped borate phosphors with high energy transfer efficiency and excellent thermal stability

Abstract

Improving the luminescence intensity of luminescent materials through energy transfer processes within a single matrix is a well-established method. Nonetheless, the energy transfer efficiency between two rare earth ions, coupled with discrepancies in their thermal stability, can result in challenges such as diminished efficiency and color drift. Therefore, in this work, a borate KSr₄B₃O₉ host with a rigid structure was selected by doping Ce³⁺/Ln³⁺ (Ln = Tb, Sm, Dy). X-ray diffraction and Rietveld refinement were employed to establish the phase purity and explore the refined structure. The compounds were characterized by a stable orthorhombic structure, and the preference occupation of Ce³⁺/Ln³⁺ was determined based on the structural information. The energy transfer from Ce³⁺ to Ln³⁺ ions resulted in the emission of several colors from the generated phosphors when excited at 351 nm. An energy transfer model from Ce³⁺ to Ln³⁺ was established, and the energy transfer efficiency between Ce³⁺ and Ln³⁺ was evaluated using luminescence spectra and decay curves, and the high transfer efficiency was calculated to be close to 76.98% (Ce³⁺ → Tb³⁺), 93.24% (Ce³⁺ → Sm³⁺), and 87.53% (Ce³⁺ → Dy³⁺). Furthermore, the phosphors demonstrated remarkable thermal stability and synchronized thermal degradation of various luminescence centers, ensuring exceptional color stability at elevated temperatures. In conclusion, the findings indicate that KSr₄B₃O₉: Ce³⁺/Ln³⁺ phosphors exhibit significant potential for application in the fields of multicolor displays and solid-state lighting.