Layer-structure-suppressed concentration quenching of Dy3+ luminescence and the realization of a single phase white light-emitting phosphor cooperated with Tm3+

Abstract

The trivalent dysprosium-doped yellow phosphor is an important component for realizing single-matrix white light. However, concentration quenching and thermal quenching greatly limit its application. White light phosphors, Li₃Ba₂Gd₃(WO₄)₈:Dy³⁺,Tm³⁺, with a stratified scheelite structure were prepared via a high-temperature solid-reaction. Calculated using the Kubelka–Munk model, the band gap of the host is 3.71 eV, which is suitable for near-ultraviolet white LEDs. The matrix is a highly disordered monoclinic crystal with a layered structure, which suppresses the concentration quenching effect of Dy³⁺ and achieves a relatively high doping concentration. A small amount of Tm³⁺ (3%) was co-doped with Dy³⁺ to obtain standard white light, whose CIE coordinate locates at (0.3370, 0.3213). Furthermore, the thermal quenching properties of Li₃Ba₂Gd₃(WO₄)₈:12%Dy³⁺,3%Tm³⁺ were investigated, and it was found that the intensity of the phosphor at 422 K maintains 82.52% of that at room temperature, and remained at 71.34% when the temperature increased to 472 K. The results indicate that the Li₃Ba₂Gd₃(WO₄)₈:Dy³⁺,Tm³⁺ phosphor can be a potential single-phased white-light-emitting phosphor for NUV white LEDs.