白光LED用稀土荧光粉的制备和性质

在还原气氛保护下利用高温固相法合成了化学组分为(M₁,M₂)₁₀(PO₄)₆X₂(M₁=Ca,Sr,Ba;M₂=Eu,Mn;X=F,Cl,Br)的可被紫光激发的蓝光、绿光和红光荧光粉,制备了紫光LED芯片+蓝光荧光粉+YAG荧光粉的二基色白光LED;紫光LED芯片+蓝光荧光粉+红光荧光粉的二基色白光LED,以及紫光LED芯片+蓝光荧光粉+绿光荧光粉+红光荧光粉的三基色白光LED。测试了所有制备的白光LED在不同的直流电驱动下的色度坐标、相关色温和显色指数。

Fabrication and Properties of Rare Earth Phosphors and Their Applications in White-light LEDs

Three types of white-light LEDs consisted of "blue LED chip and YAG phosphor","blue LED chip,YAG phosphor and red phosphor",and "blue LED chip,green phosphor and red phosphor" were fabricated.Their CIE parameters were also mearsued under 20 mA DC driving.The CIE coordinates are (0.326,0.339),(0.326,0.339),and(0.324,0.324);the correlated color temperature T_c are 5781,5627,and 5937 K;and the color-rendering index Ra are 82.3,86.2,and 92.2,respectively.It shows that the adding of red light into the white light will improve the quality of the white light.The different DC driving,increasing of the current from 5.0 mA to 6.0 mA,results in higher color temperature T_c and lower color rendering index.It was found that the red phosphor saturated when the current was higher than 30 mA.The phosphors(M₁,M₂)₁₀(PO₄)₆X₂(M₁=Ca,Sr,Ba;M₂=Eu,Mn;X=F,Cl,Br) have been synthesized in reductive atmosphere at 900～1200℃ for 2.0～8.0h.The phosphors with different compositions give the emission at 455,477,500,and 580 nm when excited by 400 nm near UV light.Three types of white LEDs were fabricated using UV LED chips and the phosphors mentioned above.The constitutions are "UV LED chip,blue phosphor,and YAG phosphor","UV LED chip,blue phosphor and red phosphor",and "UV LED chip,blue phosphor,green phosphor and red phosphor".Their CIE coordinates are(0.303,(0.329)),(0.327,0.328),and(0.331,0.333);the correlated color temperature T_c are 7070,5747,(5566) K;and the color-rendering index Ra are 79.2,80.4,and 87.9 under 20 mA DC driving,respectively.The different DC driving,increasing of the current from 5.0 mA to 6.0 mA result in a higher color temperature T_c and a lower color rendering index.However,CIE coordinate of the white light LED consisted of UV LED chip,blue phosphor and YAG phosphor changed the least.