Synthesis and photoluminescence of green-emitting Ce3+,Tb3+ co-doped Al6Si2O13 phosphors with high thermal stability for white LEDs

Abstract

In this article, novel green-emitting Ce³⁺,Tb³⁺ co-doped Al₆Si₂O₁₃ phosphors have been successfully prepared by a high-temperature solid-state reaction method using Al₂O₃, SiO₂, CeO₂, and Tb₄O₇ powders as initial materials. Single-phased and good-crystallized phosphors have been obtained after calcining the mixed powders at 1470 °C under a weak reducing atmosphere. The average particle size of the as-synthesized phosphors is less than 20 μm. The optimized doping concentration of Tb³⁺ ion is determined to be 8 mol%. With Ce³⁺ co-doping as a sensitizer, the luminescence intensity of the Al₆Si₂O₁₃:Ce³⁺/Tb³⁺ phosphors drastically improves as the Ce³⁺ doping concentration increases to 1.3 mol%. The Ce³⁺,Tb³⁺ co-doped Al₆Si₂O₁₃ phosphors exhibit intense green emissions at 488, 541, 584, and 620 nm, which correspond to the characteristic level transition of ⁵D₄-⁷F₆, ⁵D₄-⁷F₅, ⁵D₄-⁷F₄, and ⁵D₄-⁷F₃ of Tb³⁺ ion, respectively. And Al₆Si₂O₁₃:8%Tb³⁺,1.3%Ce³⁺ possesses a decay time of 31.4 ns, as well as a quantum yield of ∼45.7%. In addition, the solid-state synthesized Al₆Si₂O₁₃:Ce³⁺/Tb³⁺ phosphor powders have comparable green luminescence properties and better thermal stability compared with available commercial green phosphors. In this regard, our target products, Al₆Si₂O₁₃:Ce³⁺/Tb³⁺, may potentially serve as green-emitting phosphors for UV-converted white LEDs.