High efficiency blue-emitting phosphor: Ce3+-doped Ca5.45Li3.55(SiO4)3O0.45F1.55 for near UV-pumped light-emitting diodes

Abstract

A novel blue-emitting phosphor, Ca_5.45Li_3.55(SiO₄)₃O_0.45F_1.55:Ce³⁺, was synthesized by a solid-state reaction, and the phase formation, crystal structure and luminescence properties were investigated in detail. The Ca_5.45Li_3.55(SiO₄)₃O_0.45F_1.55:Ce³⁺ phosphor shows a highly intense blue emission peaking at about 470 nm upon near-ultraviolet (n-UV) excitation, which corresponds to the Ce³⁺ luminescence center substituting the seven-coordinated Ca²⁺ sites in the lattice. The critical quenching concentration of Ce³⁺ in the Ca_5.45Li_3.55(SiO₄)₃O_0.45F_1.55:Ce³⁺ phosphor was about 3 mol%, and the corresponding concentration quenching mechanism was verified to be the dipole–dipole interaction. Upon excitation at 365 nm, the composition-optimized Ca_5.42Li_3.55(SiO₄)₃O_0.45F_1.55:0.03Ce³⁺ exhibited a high quantum efficiency of 82%, and its luminescence intensity at 150 °C decreases to 71% of the initial value at room temperature. The above results indicate that Ca_5.45Li_3.55(SiO₄)₃O_0.45F_1.55:Ce³⁺ is a promising candidate as a blue-emitting n-UV convertible phosphor for application in white light emitting diodes (w-LEDs).