QQ客服 官方微博 反馈留言

题名	用于白光LED的YAG荧光陶瓷材料的制备及光学性质研究
作者	邵秀晨
文献子类	硕士
导师	唐燕如
关键词	Ce:YAG Ce:YAG 白光LED WLED 荧光陶瓷 ceramic phosphor 稀土掺杂 rare-earth doping
其他题名	The Preparation and Optical Properties of YAG Ceramic Phosphors for White Light-emitting Diodes
英文摘要	上世纪末开始，随着高亮度蓝光LED的发明与成熟，封装黄色YAG荧光粉制成的白光LED作为第四代光源逐渐开始大规模应用。半导体白光LED因其具有的节能环保，工作寿命长等突出亮点，已广泛应用于生产生活的方方面面。荧光型白光LED目前常用的封装手段是用有机硅胶将黄色YAG荧光粉贴合在蓝光LED表面，这种类型的白光LED存在发光效率衰退，高功率照明条件下有机材料寿命短，且有机物稳定性较差等问题。同时，目前普遍使用的Ce:YAG荧光粉其发射光谱的红光部分强度不足，导致白光LED器件的显色性能较差，对整体光学性能有较为明显的影响。 为提高白光LED在高功率下稳定性，同时尽可能的提升白光LED器件的发光效率，显色指数等指标，进而提高白光LED光学性能，本文使用真空固相烧结法制备了基于Ce:YAG的荧光陶瓷样品。利用XRD，SEM等手段，表征了样品的物相及结构特征；利用分光光度计 表征样品的吸收光谱；将样品与发射波长为447nm的蓝光LED芯片结合，测试其荧光光谱。还利用退火等方法进一步研究样品特性。基于以上实验方法，本文主要工作及结果如下： 1、Ce:YAG引入应力后对白光性能的影响 通过减少Y2O3用量成功在晶格内引入空位，且SEM图像上直观的看到了这种掺入空位的方法所引入的应力在晶体中的分布。应力的引入导致晶格场振动模式增加，提高了非辐射跃迁的几率，从而导致光效下降。当Y空位超过2.22%，YAG样品的晶格中无法再容纳更多应力，会直接出现Al2O3第二相，使得样品的发光效率回升。对样品进行1200℃退火处理，保温5小时，能够有效消除晶格内的应力，提升样品光效。 2、蓝光激发Ce:YAG掺杂Gd后的白光性能 Gd3+会取代部分Y3+进入格位，使得晶格常数增加，因此Ce3+会受到Gd3+掺杂的影响，其吸收蓝光的能力随着Gd3+掺杂浓度的增加而降低，Ce3+的发射光谱的峰值波长也从534nm向564nm方向红移。此外，样品的光效从81.45lm/W下降到63.70lm/W，显色指数从61.3升高到70.2。Gd掺杂改善了显色指数，使得Ce:YAG荧光陶瓷应用于白光LED的性能得到了提高。 3、Al2O3-Ce:YAG复合相荧光陶瓷掺杂Ga，Gd及Tb对白光性能的影响 在Al2O3-Ce:YAG复合相陶瓷中分别掺入Ga，Gd及Tb。实验结果表明，随着掺杂Ga浓度增加，样品的发射峰蓝移，绿光成分增多；样品内出现较大气孔，光效从62.78lm/W下跌到47.77lm/W。此外，Gd掺杂的样品显色指数从66.3提高至72.7，光效从85.7lm/W下降到71.31lm/W。Tb掺杂的样品显色指数从58.2提高到65.8，发光效率从71.72lm/W提高到87.89lm/W。 比较第四第五章掺杂Gd后的实验结果，复合相在相同掺杂条件下，其显色指数与光效均明显高于单相Ce:YAG样品，说明了第二相体系在提升荧光粉发光性能方面有较大的研究价值。; Since the end of the last century, with the invention and maturation of high-brightness blue LEDs, WLEDs packed with yellow YAG phosphors have gradually begin to be used as a fourth-generation light source. WLEDs have been widely used in production and life due to their energy conservation, environmental protection, long working life and so on. The common way to fabricate Fluorescent WLEDs is to packaging yellow YAG phosphors on the surface of blue LED with organic silica gel. This type of WLED has a lot of problem such as decline in luminous efficiency, short working time due to the using of organic materials. Ce:YAG phosphors also lack of red emission spectrum and this result in a poor color rendering performance of the white LED device. In order to improve the stability of WLEDs under high import power and obtain better luminous efficiency and color rendering index(CRI), this thesis base on Ce:YAG ceramic phosphors fabricate by vacuum sintering method. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used and the absorption spectrum was characterized by a spectrophotometer. The sample was combined with a blue LED chip emitting at a wavelength of 447 nm to measure the fluorescence spectrum. The sample is annealed to get more date. The main contribution of this paper is as follows: 1. The influence on white light performance after introduce vacancy into the Ce:YAG lattice We successfully introduce vacancy into the lattice by reducing the concentration of Y2O3, and the distribution of the stress was visually observed on the SEM image. The stress leads to more lattice mode, which increases the probability of non-radiative transitions and result in a decrease in the luminous efficiency. After Y vacancy exceed 2.22%, the composite phase of Al2O3 arise result in the LE recovery to 94.05lm/W. The samples were annealed at 1200℃ for 5 hours to eliminate the stress in the grains, and result to the increase of Luminous efficiency. 2. Ce:YAG Ceramic Phosphors with Gd3+ Doping for WLEDs As Gd content increased, the Gd3+will replace the lattice position of Y3+ into the lattice. The absorption of blue light and relative photoluminescence (PL) intensity of the (Gd,Y)3Al5O12:Ce ceramic phosphors decreased as Gd content increased, leading to a reduction in the luminous efficacy from 81.45lm/W to 63.70lm/W. Moreover, the PL emission bands of (Gd,Y)3Al5O12:Ce exhibited redshift from 534nm toward 564 nm and result to the increase of the color rendering index from 61.3 to 70.2. Although the doping of Gd decreases the luminous efficacy, the color rendering index of the (Gd,Y)3Al5O12:Ce sample is significantly increased, and the performance of the yellow YAG ceramic phosphor applied to the white LED is improved. 3. Composite phase ceramic phosphors of Al2O3-Ce:YAG doping with Ga, Gd and Tb WLEDs Ga, Gd and Tb were doped in Al2O3-Ce:YAG composite ceramics respectively. For Ga doped samples, the emission peak shows blue-shift. As Ga concentration arise, pores with 35μm appeared. The LE drops from 62.78 lm/W to 47.77 lm/W. After Gd doping, the CRI increased from 66.3 to 72.7, and the LE decreased from 85.7 lm/W to 71.31 lm/W. After the Tb doping, the CRI increased from 58.2 to 65.8 and the LE increased from 71.72 lm/W to 87.89 lm/W. Comparing the Gd concentration result in chapter 4 and 5, composite phase samples have better performance in CRI and LE. This indicate that the composite phase system has a good research value in improving the WLED performance.
学科主题	材料学
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/31083]
专题	中国科学院上海光学精密机械研究所
作者单位	中国科学院上海光学精密机械研究所
推荐引用方式 GB/T 7714	邵秀晨. 用于白光LED的YAG荧光陶瓷材料的制备及光学性质研究[D].

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。