有机硅树脂/稀土荧光粉复合膜的制备及其光学性能研究
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摘要
通过热压成膜工艺制备了不同稀土荧光粉质量分数和厚度组合的有机硅树脂/稀土荧光粉复合膜材料并封装成白光LED,利用荧光分光光度计、紫外-可见光-近红外光谱分析系统对该复合膜材料的激发与发射光谱、荧光转换效率和白光LED的辐射发光效率、色坐标等光学性能进行了测试表征,并对其机理进行了分析。结果表明:有机硅树脂/稀土荧光粉复合膜材料的激发与发射主峰值分别为460 nm和550 nm,对应于稀土Ce~(3+)的~2F_(7/2)→5d跃迁和5d→4f跃迁,其光谱强度与荧光粉质量分数和复合膜厚度均呈正相关,而荧光转换效率则表现出负相关趋势。白光LED的辐射发光效率则随着荧光粉质量分数和膜层厚度的增加而增大,其色坐标点的变化满足线性方程y=1.797x-0.239(线性相关系数R~2=0.999);在荧光粉质量分数为7%、膜层厚度为0.5 mm时,由有机硅树脂/稀土荧光粉复合膜材料制备的白光LED色坐标点(CIE-x=0.3144,CIE-y=0.3260)正好落于白光区的黑体辐射曲线上,因此该点为最优坐标点,其相应的荧光转换效率为78%,辐射发光效率为314.2 lm/W,色温为6 432 K,表现为正白光,表明该复合膜是一种适用于白光LED的材料。
Silicone resin/rare earth phosphor composite films with different phosphor mass fractions and thickness were prepared by hot-pressing, and then packaged into white LED. The excitation and emission spectra of the composite films were measured by fluorescence spectrophotometer and UV-Vis-NIR spectroscopy analysis system. The fluorescence conversion efficiency, luminescence efficiency of radiation and color coordinates of white LED were tested and characterized, and the mechanism was analyzed also. The results show that the main excitation and emission peaks of the composite films are 460 nm and 550 nm, respectively, corresponding to the ~2F_(7/2)→5 d and 5 d→4 f transition emission of rare earth Ce~(3+). The spectral intensity is positively correlated with phosphor mass fraction and film thickness, while the fluorescence conversion efficiency is negatively correlated. The color coordinate point(CIE-x=0.3144, CIE-y=0.3260) of white LED prepared by the composite film materials falls on the black body radiation curve of white light region when the mass fraction is 7% and the thickness is 0.5 mm. Thus the point is the optimal coordinate point, and the corresponding fluorescence conversion efficiency is 78%, the radiation luminescence efficiency is 314.2 lm/W, color temperature is 6 432 K, showing white light. It means that the composite film is a suitable material for white LED.
Silicone resin/rare earth phosphor composite films with different phosphor mass fractions and thickness were prepared by hot-pressing, and then packaged into white LED. The excitation and emission spectra of the composite films were measured by fluorescence spectrophotometer and UV-Vis-NIR spectroscopy analysis system. The fluorescence conversion efficiency, luminescence efficiency of radiation and color coordinates of white LED were tested and characterized, and the mechanism was analyzed also. The results show that the main excitation and emission peaks of the composite films are 460 nm and 550 nm, respectively, corresponding to the ~2F_(7/2)→5 d and 5 d→4 f transition emission of rare earth Ce~(3+). The spectral intensity is positively correlated with phosphor mass fraction and film thickness, while the fluorescence conversion efficiency is negatively correlated. The color coordinate point(CIE-x=0.3144, CIE-y=0.3260) of white LED prepared by the composite film materials falls on the black body radiation curve of white light region when the mass fraction is 7% and the thickness is 0.5 mm. Thus the point is the optimal coordinate point, and the corresponding fluorescence conversion efficiency is 78%, the radiation luminescence efficiency is 314.2 lm/W, color temperature is 6 432 K, showing white light. It means that the composite film is a suitable material for white LED.
引文
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[2]史光国.半导体发光二极管及固体照明[M].北京:科学出版社,2007:1-23.
[3]Luo X,Fu X,Chen F,et al.Phosphor self-heating in phosphor converted light emitting diode packaging[J].International Journal of Heat&Mass Transfer,2013,58(1-2):276-281.
[4]Qiu Y,Zhang B.Optical properties of remote phosphorconverted white LEDs[J].Semiconductor Optoelectronics,2012,33(2):168-170.
[5]Jia J,Li D,Jia H,et al.Effect of composition and package structure of bi-color flexible remote phosphor film on the properties of remote white LEDs[J].Optical Materials,2017,72:602-611.
[6]Narendran N,Gu Y,Freyssinier-Nova J P,et al.Extracting phosphor-scattered photons to improve white LEDef ciency[J].Physica Status Solidi,2005,202(6):R60-R62.
[7]肖华,吕毅军,徐云鑫,等.传统白光LED与远程荧光粉白光LED的发光性能比较[J].发光学报,2014,35(1):66-72.
[8]Lin M T,Ying S P,Lin M Y,et al.Inverted-cone-lens encapsulant with gradient surface for ring-remote-phosphor structure[J].IEEE Transactions on Device&Materials Reliability,2014,14(1):358-364.
[9]Wang S,Peng Y,Li R,et al.Enhancement in light extraction of white leds using micro-cone patterned phosphor-inglass[C]//China Semiconductor Technology International Conference,2016:1-3.
[10]Zhao Y,Xu H,Zhang X,et al.Facile synthesis of YAG:Ce3+thick films for phosphor converted white light emitting diodes[J].Journal of the European Ceramic Society,2015,35(13):3 761-3 764.
[11]Yang L,Chen M,Lv Z,et al.Preparation of a YAG:Ce phosphor glass by screen-printing technology and its application in LED packaging[J].Optics Letters,2013,38(13):2 240-2 243.
[12]杨爽,康瑞琴,郭常颖,等.LED用聚碳酸酯基荧光转换膜的制备与研究[J].化工新型材料,2015,43(6):83-85.
[13]Yu S,Li Z,Liang G,et al.Angular color uniformity enhancement of white light-emitting diodes by remote micro-patterned phosphor film[J].Photonics Research,2016,4(4):140-145.
[14]杨隽,闫卫平,李明伟,等.溶胶-凝胶法合成YAG:Ce3+荧光粉及其发光性能研究[J].中国稀土学报,2005(S2):27-29.
[15]Jeon S W,Noh J H,Kim K H,et al.Improvement of phosphor modeling based on the absorption of Stokes shifted light by a phosphor[J].Optics Express,2014,22(S5):A1 237-A1 242.
[16]卓宁泽,张娜,李博超,等.TiO2微粒对远程荧光粉膜及白光发光二极管器件光色性能的影响[J].物理学报,2016,65(5):348-354.
[17]Erdem T,Nizamoglu S,Demir H V.Computational study of power conversion and luminous efficiency performance for semiconductor quantum dot nanophosphors on light-emitting diodes[J].Optics Express,2012,20(3):3 275-3 295.