Color-tunable up-conversion emission from Yb3+/Er3+/Tm3+/Ho3+ codoped KY(MoO4)2 microcrystals based on energy transfer

Tunable up-conversion luminescent material KY(MoO4)2: Yb3+, Ln3+ (Ln=Er, Tm, Ho) has been synthesized by a typical hydrothermal process. Under 980 nm laser diode (LD) excitation, the emission intensity and the corresponding luminescence colors of KY(MoO4)2: Yb3+, Ln3+ (Ln=Er, Tm, Ho) have been investigated in detail. The energy transfer from the Yb3+ sensitizer to Ho3+, Er3+ and Tm3+ activators plays an important role in the development of color-tunable single- phased phosphors. The emission intensity keep balance through control of the Ho3+ co-doping concentrations, white light was experimentally shown at KY(MoO4)2: 20 mol% Yb3+, 0.8 mol% Er3+, 0.5 mol% Tm3+, 1.0 mol% Ho3+ phosphor with further calcination at 800 °C for 4 h under 980 nm laser excitation. The color tunability, high quality of white light and high intensity of the emitted signal make these up-conversion (UC) phosphors excellent candidates for applications in solid-state lighting.