白光LED用荧光材料的湿化学法制备及性能研究

发布时间：2018-07-06 07:53

本文选题：白光发光二极管 + 荧光材料　；参考：《太原理工大学》2011年博士论文

【摘要】：发光二极管(Light Emitting Diode,LED)作为绿色、节能、长寿的新一代照明和显示器件中的光源,将在未来几年内大规模取代传统光源,已成为国内外学术界和产业界的共识。随着半导体照明技术的发展和推广应用,白光LED的研究已经引起各国科研机构的高度重视。由于荧光材料是白光LED的关键材料之一,因此开展白光LED专用荧光材料的研究,无疑具有重要现实意义。本文分别采用高分子网络凝胶法、改进的溶胶-凝胶法及淀粉燃烧法等湿化学方法制备了铈掺杂钇铝石榴石系列、碱金属偏钒酸盐系列和稀土离子掺杂的锶铈氧化物系列荧光材料,并着重对其发光性能进行了表征,探讨了其发光机理。 (1)制备了能够与GaN基蓝光LED芯片匹配的Y2.94-xCe0.06GdxAl5O12和Y2.94-xCe0.06PrxAl5O12荧光材料。Gd3+的掺杂通过使Y2.94-xCe0.06GdxAl5O12中Ce3+的光谱红移来改善白光质量,其最佳掺杂量x为0.6；Pr3+的掺杂通过在Y2.94-xCe0.06PrxAl5O12中Ce3+黄光发射带上增加红色线发射以改善白光质量,其最佳掺杂量x为0.01。 (2)采用聚乙烯吡咯烷酮(PVP)对纳米YAG:Ce,Gd进行了表面修饰。PVP添加浓度为1.37wt%时,光致发光强度增强约1.83倍。究其原因不仅归因于PVP的空间位阻效应减少了粉体颗粒间的团聚,而且得益于PVP对纳米颗粒的表面钝化。 (3)制备了能够与紫外或近紫外LED芯片相匹配的具有宽激发(吸收)与宽发射带的碱金属偏钒酸盐(AV03),以单一基质实现了白光。理论计算及实验研究结果表明AV03的发光均为V04四面体中O2-的2p轨道到V5+的3d空轨道的单电子电荷转移跃迁所致。 (4)系统地研究了丙三醇、聚乙二醇(PEG). PVP表面修饰CsVO3的发光性能之后,发现添加2.10wt%的PVP或PEG制备CsVO3可以分别提高其发光强度2.53倍、3.18倍。通过研究P(S-MMA)聚合物和Si02与CsVO3复合后对发光性能的影响表明CsVO3/P(S-MMA)荧光微球避免了CsVO3荧光粉的团聚,其复合荧光薄膜扩展了CsVO3在柔性发光与显示器件中的应用；铯硅质量比为1：6的CsVO3/SiO2在大气环境下存放12个月后荧光发射强度仅衰减了2%,较优的光学稳定性有利于其在白光LED中的应用。 (5)选取Sm3+、Dy3+和Eu3+作为激活离子,采用单、双掺杂的方式制备出能够与紫外或近紫外LED芯片匹配的单一基质、颜色可调的Sr2CeO4系列荧光材料。理论计算及实验研究结果表明Sr1.964Eu0.03Dy0.006CeO4白光材料光色特性较优,相应色坐标为(0.391,0.372),相关色温为3647K。 Sr2CeO4的光致发光来源于晶体结构中两种不同的Ce4+-O2-电荷转移带跃迁。Eu3+单掺杂Sr2Ce04的光致发光主要为能量传递机理,特别地,Eu3+-Dy3+双掺杂Sr2Ce04的发光不仅存在Sr2Ce04与Eu3+和Dy3+、Eu3+和Dy3+之间的能量传递过程,还存在Sr2Ce04晶体中缺陷的影响。
[Abstract]:As a new generation of light source in green, energy-saving and long-lived lighting and display devices, Light emitting Diode (LED) will replace the traditional light source on a large scale in the next few years, which has become the consensus of academia and industry at home and abroad. With the development and application of semiconductor lighting technology, the research of white LED has been paid great attention to by scientific research institutions all over the world. As fluorescent materials are one of the key materials of white LED, it is undoubtedly of great practical significance to study the special fluorescent materials for white LED. In this paper, the series of cerium doped yttrium aluminum garnet were prepared by macromolecule network gel method, modified sol-gel method and starch combustion method. The luminescent properties of alkaline metavanadate series and rare earth ions doped strontium cerium oxide series were characterized. The luminescence mechanism of Y2.94-xCe0.06GdxAl5O12 and Y2.94-xCe0.06PrxAl5O12 was investigated. (1) the doping of Y2.94-xCe0.06PrxAl5O12 and Y2.94-xCe0.06PrxAl5O12 improved the white light quality by red-shifting the spectra of Ce3 in Y2.94-xCe0.06GdxAl5O12. The white light quality can be improved by adding red line emission to the yellow emission band of ce 3 in Y2.94-xCe0.06PrxAl5O12. The optimum doping amount x is 0.01.2.2.When the surface modification of nano-YAGWO-Ce5O12 was carried out by polyvinylpyrrolidone (PVP), the concentration of PVP was 1.37 wt%. The intensity of photoluminescence increased by about 1.83 times. The reason is not only due to the space steric resistance effect of PVP, but also to the reduction of agglomeration between particles. In addition, due to the surface passivation of nanoparticles by PVP. (3) Alkali metal metavanadate (AV03) with wide excitation (absorption) and wide emission band (AV03), which can match ultraviolet or near-ultraviolet LED chips, was prepared and white light was realized by a single substrate. The theoretical and experimental results show that the luminescence of AV03 is due to the single electron charge transfer transition from the O _ 2-O _ 2p orbital to the 3D empty orbit of V _ 5 in the V _ 04 tetrahedron. (4) Propanetriol and polyethylene glycol (PEG) have been systematically studied. After modification of CsVO3 with PVP surface, it was found that the luminescence intensity of CsVO3 prepared by adding 2.10wt% PVP or PEG could be increased by 2.53 times or 3.18 times, respectively. The effects of P (S-MMA) polymer and Si02 / CsVO3 on the luminescence properties of CsVO3 phosphors were investigated. It was shown that CsVO3 / P (S-MMA) fluorescent microspheres could avoid the agglomeration of CsVO3 phosphors, and the composite fluorescent films extended the applications of CsVO3 in flexible luminescence and display devices. CsVO _ 3 / Sio _ 2, whose mass ratio of cesium to silicon is 1:6, only attenuates the emission intensity of CSV _ 3 / Sio _ 2 in atmospheric environment for 12 months, and the better optical stability is favorable for its application in white LED. (5) Sm ~ 3 Dy _ 3 and EU _ 3 are selected as activation ions. A series of Sr2CeO4 fluorescent materials, which can match ultraviolet or near-ultraviolet LED chips, have been prepared by double doping method, and the color of Sr2CeO4 can be adjusted. The theoretical calculation and experimental results show that the photochromatic properties of Sr1.964Eu0.03Dy0.006CeO4 are better, the corresponding color coordinate is (0.391U) 0.372, and the correlation color temperature is 3647K. The photoluminescence of Sr _ 2CeO _ 4 originates from the energy transfer mechanism of two different ce _ 4-O _ 2-charge transfer band transitions. In particular, there exists not only the energy transfer process between Sr2Ce04 and EU3, Dy3 + EU3 and Dy3, but also the effect of defects in Sr2Ce04 crystal on the luminescence of Eu3-Dy3 doped Sr2Ce04.
【学位授予单位】：太原理工大学
【学位级别】：博士
【学位授予年份】：2011
【分类号】：TN104.3

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