Highly efficient Sr3Y2(Si3O9)2:Ce3+,Tb3+/Mn2+/Eu2+ phosphors for white LEDs: structure refinement, color tuning and energy transfer

Abstract

A series of highly efficient and emission-tunable Sr₃Y₂(Si₃O₉)₂(SYSO):Ce³⁺,Tb³⁺/Mn²⁺/Eu²⁺ phosphors have been prepared via a solid-state reaction. The structure refinement indicates that the as-prepared phosphors crystallized in a monoclinic phase with a space group of C2/c (no. 15), and there are three kinds of cation sites in the host lattice for the doped ions to occupy. The Ce³⁺ emission at different lattice sites in the SYSO host has been firstly identified and discussed. When introducing other doping ions into these cation sites, there exist efficient energy transfers from Ce³⁺ ions to these doping ions (Tb³⁺, Mn²⁺, and Eu²⁺) under UV excitation. The corresponding energy transfer mechanisms from Ce³⁺ to Tb³⁺/Mn²⁺/Eu²⁺ in SYSO:Ce³⁺,Tb³⁺/Mn²⁺/Eu²⁺ systems have been studied systematically. These energy transfers not only can enhance the luminescent efficiencies and broaden the width of emission spectra of SYSO:Ce³⁺,Tb³⁺/Mn²⁺/Eu²⁺ phosphors but also can modulate their emission colors from blue to green, orange or cyan, respectively. For example, the maximum quantum yields (QYs) of as-prepared SYSO:0.15Ce³⁺,xTb³⁺/yMn²⁺ phosphors can reach 90.4% and 74% at x = 0.70, y = 0.01, respectively. Based on these experiment results, the as-prepared SYSO:Ce³⁺,Tb³⁺/Mn²⁺/Eu²⁺ phosphors can act as potential color-tunable and emission band-widened phosphors for possible applications in ultraviolet light based white LEDs.