Achieving The Tuneable Emitting Phosphor Using The Enengy Transfer And Its Application To LED

With the development of modern lighting and display technology,semiconductor lighting has gained an increasing attention due to its advantages such as high efficiency and environmental protection,and phosphorforlight-emitting Diodes plays a key role in the high quality and innovative development of semiconductor lighting technology.The commonly used white light implementation are“Blue LED chip+YAG:Ce³⁺yellow phosphor”,“Blue LED chip+Red and Green phosphor”or“Near UV LED chip+Tricolored Phosphorescent”,which have the problems such as color coordinate drift,high color temperature,and poor color dominance.But near ultraviolet LED chip single matrix white phosphor can avoid the problems of color reabsorption and ratio regulation,which has good stability,reproducibility,and color dominance.Based on this,new color adjustable and white phosphors have become a research hotspot in the field of luminescence.A series of phosphate and halo phosphate series phosphors were synthesized by high temperature solid phase method,including Ca₂PO₄Cl:Ce³⁺,Mn²⁺,Ba₃Ca₂（PO₄）₃F:M(M=Ce³⁺,Eu²⁺,Mn²⁺),Ba Mg₂（PO₄）₂:Ce³⁺,Tb³⁺,Mn²⁺,Ba Mg₂（PO₄）₂:Eu²⁺,Tb³⁺,Mn²⁺,and its luminescence performance and energy transfer mechanism are also studied,and obtained a single matrix white phosphor with potential application prospects in white LED.（1）A series of Ca₂PO₄Cl:Ce³⁺,Mn²⁺phosphors were first synthesized by high temperature solid phase method to investigate their luminescence properties.Under 334 nm excitation,the Ca₂PO₄Cl:Ce³⁺featured an asymmetric emission band centered at 367 nm,which overlaps more with the excitation band of Ca₂PO₄Cl:Mn²⁺,revealing the occurrence of energy transfer from Ce³⁺to Mn²⁺.And the resonance type is the electric dipole-electric dipole interaction.The orange-red emission intensity of Mn²⁺is significantly enhanced by the effective energy transfer from Ce³⁺to Mn²⁺,and the luminescence color of Ca₂PO₄Cl:Ce³⁺,Mn²⁺changes with the increase of Mn²⁺doping.（2）A series of single-phase phosphors Ba₃Ca₂（PO₄）₃F:M(M=Ce³⁺,Eu²⁺,Mn²⁺)are synthesized by high temperature solid state method,and the luminescence properties and the energy transfer mechanisms from Ce³⁺to Eu²⁺,Ce³⁺to Mn²⁺,and Eu²⁺to Mn²⁺are investigated in detail.Ce³⁺,Eu²⁺and Mn²⁺single doped Ba₃Ca₂（PO₄）₃F can demonstrate blue,green and orange-red emission,respectively.An effective energy transfer from Ce³⁺to Eu²⁺and from Ce³⁺,Eu²⁺to Mn²⁺occurs in Ba₃Ca₂（PO₄）₃F,and the emission color can change from blue to green,blue to red,green to yellow,and red to yellow in Ce³⁺and Eu²⁺,Ce³⁺and Mn²⁺,Eu²⁺and Mn²⁺,Ce³⁺,Eu²⁺and Mn²⁺doped Ba₃Ca₂（PO₄）₃F,respectively.On this foundation,Ce³⁺/Eu²⁺/Mn²⁺was doped with Ba₃Ca₂（PO₄）₃F,and the luminescence color of the obtained material was close to white.This method of obtaining color adjustable or white phosphors through multi doped ions provides an idea for the research of single matrix color changing phosphors.（3）A single matrix white phosphor Ba Mg₂（PO₄）₂:Ce³⁺,Tb³⁺,Mn²⁺was synthesized by the high temperature solid phase method.There is a spectral overlap between the emission bands of Ce³⁺and the excitation band of Mn²⁺and Tb³⁺.Time decay studies indicated the occurrence of energy transfer from Ce³⁺to Tb³⁺and Ce³⁺to Mn²⁺.The luminescence colors of Ce³⁺,Tb³⁺,Mn²⁺can be adjusted from blue to green through energy transfer between Ce³⁺and Tb³⁺,and from blue to red by energy transfer between Ce³⁺and Mn²⁺,respectively.The white light emitting diode（white light LED）was formed by combining a single matrix white phosphor Ba Mg₂（PO₄）₂:3%Ce³⁺,3%Tb³⁺,5%Mn²⁺,and 365 nm LED chips.which CIE color coordinates and color temperature（CCT）of（0.312,0.313）and 6217 K,respectively.Therefore,Ba Mg₂（PO₄）₂:Ce³⁺,Tb³⁺,Mn²⁺has potential application value in the field of white LEDs.（4）A single matrix white phosphor Ba Mg₂（PO₄）₂:Eu²⁺,Tb³⁺,Mn²⁺was synthesized by high temperature solid phase method.Time decay studies and other data indicated the occurrence of energy transfer process and mechanism from Ce³⁺to Tb³⁺and Ce³⁺to Mn²⁺.More importantly,compared with Ba Mg₂（PO₄）₂:Ce³⁺,Tb³⁺,Mn²⁺materials,the excitation band of Ba Mg₂（PO₄）₂:Eu²⁺,Tb³⁺,Mn²⁺is closer to the long wave direction and better matches the emission wavelength of near UV LED.The 365 nm UV chip was combined with Ba Mg₂（PO₄）₂:3%Eu²⁺,3%Tb³⁺,3%Mn²⁺to obtain white LEDs.The CIE color coordinates and related color temperatures were（0.346,0.299）and 4464 K,respectively.The results show that the material has a good application prospect in the field of indoor lighting.