Design And Luminescence Performance Of Rare Earth Pyrophosphovanadate White Light Phosphor For WLE

White light-emitting diodes（WLEDs）are regarded as a new generation of green lighting source due to their advantages of high energy saving,long life,small size and high brightness.At present,commercial WLED devices lighting sources are generally fabricated with Ga N-LED chips and YAG:Ce³⁺yellow phosphors.Nevertheless,due to the lack of red and cyan light components in this system,there are shortcomings such as high correlated color temperature（CCT>5500 K）and low color rendering index（Ra<80）,which cannot meet people’s requirements for lighting in different occasions.Therefore,designing a single-phase high-quality white-light phosphors that can be excited by ultraviolet（UV）or near-ultraviolet（NUV）has become one of the important research topics.In this paper,pyrophosphate and pyrovanadate with stable physical and chemical properties are used as the matrix.By introducing Dy³⁺,Tm³⁺,Eu³⁺,Eu²⁺and Ce³⁺ions,a series of high-quality color-tunable white-light emission phosphors are designed by traditional high-temperature solid-phase methods.Moreover,a series of WLED devices with low CCT and high CRI are fabricated with phosphors and UV LED chips,which solves the current lighting problems and promotes the progress and development of lighting technology in a certain extent.The specific work content is as follows:（1）A series of color-tunable Sr₂P₂O₇:Dy³⁺,Tm³⁺phosphors were synthesized,using the efficient energy transfer relationship between Dy³⁺and Tm³⁺ions,and by changing the doping concentration of Dy³⁺and Tm³⁺ions,the wide color-tunable emission from blue light to white light to cyan light was achieved in this phosphors.Among them,the CCT=5500 K and the CIE coordinates of（0.3292,0.3521）was achieved in the best sample Sr₂P₂O₇:0.01Dy³⁺,0.01Tm³⁺phosphor,which is almost the same as standard white light.（2）A series of high-efficiency and color-tunable Rb₂Ca P₂O₇:Ce³⁺,Eu²⁺phosphors were synthesized,the sensitization effect of Ce³⁺on Eu²⁺ions was studied,and the energy transfer relationship between Ce³⁺and Eu²⁺ions was explained.By changing the doping concentration of Eu²⁺ions,the extremely wide color-tunable emission from blue to white and then to orange was achieved.The thermal stability,internal quantum efficiency（IQE）,and external quantum efficiency（EQE）of the best sample is 61.3%,74.36%and 56.77%,respectively.Combining this sample with a 310 nm UV LED chip,a high-quality WLED device with CRI=88.4,CCT=3205 K and the CIE coordinates of（0.38,0.31）was achieved.（3）The high-quality warm white Sr₂（V,P）₂O₇:Eu³⁺phosphors were synthesized,without changing the matrix structure,the emission intensity of V₂O₇^4-was increased by introducing a certain amount of P⁵⁺ions.On this basis,the red light of Eu³⁺ions was introduced,and the full spectrum emission from 400 to 700 nm was achieved.Using the best sample Sr₂V_1.98P_0.02O₇:0.5%Eu³⁺combined with a 365 nm NUV chip,a high-quality WLED device with CRI=93.5 and CCT=3188 K was fabricated.