Preparion And Luminescence Of YVO₄: Bi, RE(RE=Eu, Dy, Er, Tm) Phosphors Used In LED

The current phosphor materials for LEDs are Y₂O₂S:Eu³⁺for red,ZnS:(Cu⁺,Al³⁺) for green,and BaMgAl₁₀O₁₇:Eu²⁺(BAM)for blue.And the green and blue phosphors have got much progress on both emission intensity and color rendering,Unfortunately, the efficiency of the Y₂O₂S:Eu³⁺red phosphor is about 8 times less than that of the green and blue phosphors,and the lifetime and stability of the Y₂O₂S:Eu³⁺material is inadequate;these reasons hold back the development of white LEDs.In our paper,we prepared YVO₄:Eu new red LED phosphors by solid state reaction,and enlarge the excitation spectra by co-doping Bi³⁺,this make the excitation under 365nm much stronger,thus the phosphors can be used in LED.Series of experiments were also done to improve the emission intensity and color rendering by substituting V⁵⁺with Nb⁵⁺or P⁵⁺.XRD patterns,excitation spectra and emission spectra have been measured on the samples.The results indicated that:YVO₄:Bi³⁺,Eu³⁺had good luminescence property and chromaticity under 365nm excitation,the excitated band was broaden to exceed 400nm after doping Bi³⁺,the optimal Bi-doping concentration was 10 mol%. We also found that the doping of Nb⁵⁺and p⁵⁺enhanced the luminescence,the optimal doping concentration were 5mol%both,the emission intensity of Y_0.85Bi_0.1Eu_0.05V_0.95Nb_0.05O₄ and Y_0.85Bi_0.1Eu_0.05V_0.95P_0.05O₄ sample was 1.79 times and 1.56 timeshigher than the commercial Y₂O₂S:Eu³⁺phosphors,respectively,and their color rendering was(0.668,0.331).Aluminums were doped in to improve the emission intensity.Meanwhile,we obtained YVO₄:Bi,Dy/Er yellow phosphors and YVO₄:Bi, Tm blue phosphors by solid state reaction.It was possible to emit red,yellow and blue light from the same host material YVO₄ by doping different rare ions,and thus white light was obtained.What is more,cold white light or warm white light can be adjusted by changing the concentration of rare ions.This will make some sense in LED phosphors.