稀土掺杂YAG荧光膜的制备与发光性能研究

发布时间：2018-06-05 14:31

本文选题：YAG荧光膜 + 白光LED　；参考：《电子科技大学》2016年博士论文

【摘要】：YAG:Ce~(3+)荧光材料转换白光LED具有发光效率高、能耗低、寿命长和安全可靠等优点,是新一代全固态照明光源,在照明市场中占据不可代替的地位。但是,商业YAG:Ce~(3+)荧光粉体颗粒较大且形貌不规则分布不均匀,不可避免地产生背反射与背散射,导致能量转换效率下降;此外,荧光粉/环氧树脂层的差导热性会引起荧光材料温度猝灭,环氧树脂层受长时间的热辐射会泛黄或发生脱落,降低白光LED使用的稳定性与寿命。透明YAG:Ce~(3+)荧光膜有着更小与更均匀的颗粒尺寸、更强的附着力、更好的导热性、特别是有着较小的背反射与背散射效应,被认为是作为白光LED良好荧光转换层,受广泛研究者所关注。论文研究的出发点是制备可应用在白光LED上的高效发光性能的稀土掺杂YAG荧光膜,研究所取得结果如下:1.采用粉末靶材在石英基片上制备YAG:3.3%Ce~(3+)荧光膜,对溅射过程中的溅射功率、氧气含量与退火工艺对沉积速率及性能的影响进行系统研究。由于粉末靶原子的表面结合能低于传统高温烧结陶瓷靶,薄膜的沉积速率得到了提高,达1.2μm/h。在最佳工艺条件下溅射2h,沉积薄膜厚度达2.92μm,经在H2/Ar还原气氛1100℃烧结10 h,薄膜为纯相YAG膜,在450 nm激发下,发光量子产率达23%。2.采用具有高溶解能力的乙二醇作为溶胶的溶剂,实现了高浓度溶胶下制备YAG:3.3%Ce~(3+)荧光膜,涂膜40层,所制备YAG:Ce~(3+)荧光膜为80 nm颗粒紧密堆积而成,厚度达4.3μm。所制备YAG:Ce~(3+)荧光膜在可见光区域有着良好的透光性的同时,在蓝光区有着强吸收峰,发光量子产率达47%,可作为在白光LED的荧光转换层。3.以硝酸盐为原材料、尿素与氨基乙酸为辅助燃料采用溶胶燃烧法在较低温条件下制备了YAG:3.3%Ce~(3+)荧光膜,在40层重复涂膜,膜层为大小约50 nm颗粒紧密堆积而成,膜厚达5.1μm。所制备的YAG:3.3%Ce~(3+)荧光膜在蓝光区有着强吸收峰,波长大于500 nm处有着良好的透光性,发光量子产率达56%。所YAG:3.3%Ce~(3+)荧光膜可应用在白光LED的封装,在8V电压,100 m A电流驱动下,发光效率为82 lm/W,色温为4536K,显色指数为75.6。4.研究了石榴石母体结构对Ce~(3+)发光特性的影响。利用更大离子半径的Tb~(3+)与Gd~(3+)取代Y~(3+)所在12面体位置,会增大晶体的晶场分裂能与晶格畸变效应,因此Ce~(3+)的发光光谱半峰宽与峰值波长呈现了宽化与红移。以钪离子取代铝离子,发光光谱半峰宽呈现了宽化,但没有发生红移。适当增大石榴石的晶胞体积可减小Ce~(3+)发生荧光猝灭的概率从而提高发Ce~(3+)的发光强度;Ce~(3+)发光峰的宽化与红移有效改善白光LED的发光性能,以TAG:3.3%Ce~(3+)荧光膜所封装的白光LED的发光效率达72 lm/W,色温为4888 K,显色指数79.2;以(Y0.7Gd0.3)3Al5O12:3.3%Ce~(3+)荧光膜所封装的白光LED的发光效率为88 lm/W,色温为4356 K,显色指数达78.3,而以(Y0.25Gd0.75)3Al5O12:3.3%Ce~(3+)荧光膜所封装的白光LED,有着更高的显色指数81.2。5.论文研究了在YAG母体中Ce~(3+)→Eu~(3+)与Ce~(3+)→Pr~(3+)能量传递过程对荧光膜发光特性的影响,YAG:Ce~(3+)/Eu~(3+)与YAG:Ce~(3+)/Pr~(3+)荧光膜在红光区的发光性能均得到了提高,分别在610 nm与611 nm出现了尖锐的发光峰。Eu~(3+)的共掺杂会引起母体中的Ce~(3+)离子发生荧光猝灭,因此,虽然其在红光区的发光得到了提高,但荧光膜的整体发光强度大幅度的下降;在YAG:Ce~(3+)/Pr~(3+)荧光膜中,当Pr~(3+)的掺杂浓度小于0.75%时,发光光谱的强度仍可保持在95%以上。首次制备的Y0.7Gd0.3AG:3.3%Ce~(3+),0.5%Pr~(3+)荧光膜的发光峰红移到550 nm,在611 nm的尖锐的红光发射峰,其发光光谱强度相对YAG:3.3%Ce~(3+)也得到了提高,对封装的白光LED性能得到了改善,发光效率为84 lm/W,显色指数为83.4,色温为4327 K。6.论文以共掺杂能量传递敏化剂来增强荧光膜对激发光的吸收能力而提高了所制备荧光膜的发光特性。由于母体中含有高浓度的激发跃迁为4f→5d的Tb~(3+)离子,所制备的YTb AG:5%Eu~(3+)与YTb AG:3.3%Ce~(3+)在紫外区有着超强吸收峰,因此在275 nm激发条件下,在能量传递的作用下增强了所制备荧光膜的发光光谱强度。所制备的YTb AG:3.3%Ce~(3+)荧光膜在275 nm激发下有着明亮的黄绿光发射;YTb AG:x%Eu~(3+)荧光膜有可调控的发光性能,随着Eu~(3+)荧浓度从0%增大5%,发光可从绿光向黄绿光、黄光、橙黄光、橙红光、红光转变。
[Abstract]:YAG:Ce~ (3+) phosphor conversion white light LED has the advantages of high luminous efficiency, low energy consumption, long life and safety and so on. It is a new generation of all solid state lighting source, which occupies an incomparable position in the lighting market. However, commercial YAG:Ce~ (3+) phosphor particles are large and irregular in irregular distribution, inevitably producing back reflection and Back scattering results in a decrease in the efficiency of energy conversion; in addition, the differential thermal conductivity of the phosphor / epoxy layer causes the quenching of the temperature of the fluorescent material. The epoxy resin layer will be yellowed or fall off for a long time, reducing the stability and life of the white LED. The transparent YAG:Ce~ (3+) fluorescent film has smaller and more uniform particle sizes, and more Strong adhesion and better thermal conductivity, especially with small back reflection and backscattering effect, are considered to be a good fluorescent conversion layer of white LED, which is concerned by many researchers. The starting point of this paper is the preparation of rare earth doped YAG fluorescent films which can be applied to white light LED with high luminescence performance. The results obtained are as follows: 1 The effect of the sputtering power, oxygen content and annealing process on the deposition rate and properties of the YAG:3.3%Ce~ (3+) fluorescent film on a quartz substrate was systematically studied by using a powder target on a quartz substrate. The deposition rate of the film was increased by 1.2 Mu as the surface binding energy of the powder target atom was lower than the traditional high temperature sintered ceramic target. M/h. sputtering 2H under the optimum process conditions, the thickness of the deposited film is 2.92 u m, and is sintered at 1100 C in H2/Ar reduction atmosphere for 10 h, and the film is pure phase YAG film. Under the excitation of 450 nm, the luminescent quantum yield reaches 23%.2. using high solubility glycol as sol-gel solvent, and the preparation of YAG:3.3%Ce~ (3+) fluorescent film under high concentration sols is achieved. The film is 40 layers, and the prepared YAG:Ce~ (3+) fluorescent film is packed closely with 80 nm particles. The YAG:Ce~ (3+) fluorescent film with a thickness of 4.3 M. has good transmittance in the visible region, while the blue light region has a strong absorption peak and a quantum yield of 47%, which can be used as the raw material for the fluorescent conversion layer.3. in the white light LED, with nitrate as raw material, urea. The YAG:3.3%Ce~ (3+) fluorescent film was prepared by the sol combustion method with the amino acetic acid at a lower temperature. The 40 layer of the film was repeated on the 40 layer. The film layer was close to 50 nm particles, and the YAG:3.3%Ce~ (3+) fluorescent film prepared by the film thickness reached a strong absorption peak in the blue light region, and the wavelength was more than 500 nm with a good penetration. Photoluminescence, luminescence quantum yield up to 56%. YAG:3.3%Ce~ (3+) fluorescent film can be applied to the encapsulation of white light LED. Under 8V voltage and 100 m A current, the luminous efficiency is 82 lm/W, color temperature is 4536K, and the color index is 75.6.4. study on the effect of garnet matrix structure on Ce~ (3+) luminescence specificity. (3+) the position of the 12 sides will increase the crystal field splitting energy and the lattice distortion effect. Therefore, the half peak width and peak wavelength of the luminescence spectrum of Ce~ (3+) show broadening and red shift. The half peak width of the luminescence spectrum is broadened with scandium ions instead of aluminum ions, but the red shift does not occur. The proper increase of the cell volume of garnet can reduce the Ce~ (3+) hair. The probability of fluorescence quenching can improve the luminescence intensity of Ce~ (3+); the widening and redshift of the Ce~ (3+) luminescence peak effectively improve the luminescence of the white light LED. The luminous efficiency of the white light LED encapsulated by TAG:3.3%Ce~ (3+) fluorescent film is 72 lm/W, the color temperature is 4888 K, the color index is 79.2, and the (Y0.7Gd0.3) 3Al5O12:3.3%Ce~ (Y0.7Gd0.3) fluorescent membrane is encapsulated in white. The luminous efficiency of the light LED is 88 lm/W, the color temperature is 4356 K, the color index is 78.3, and the white light LED encapsulated with the (Y0.25Gd0.75) 3Al5O12:3.3%Ce~ (3+) fluorescent film has a higher color rendering index 81.2.5.. The effect of Ce~ (3+), Eu~ (3+) and energy transfer process on the luminescence properties of the fluorescent membrane in the YAG matrix is studied. (3 The luminescence properties of /Eu~ (3+) and YAG:Ce~ (3+) /Pr~ (3+) fluorescent films in the red light region have been improved, and the co doping of the sharp luminescence peak.Eu~ (3+) at 610 nm and 611 nm, respectively, will cause the fluorescence quenching of Ce~ (3+) ions in the parent body, therefore, although the luminescence in the red region is improved, the overall luminescence intensity of the fluorescent film is obtained. In the YAG:Ce~ (3+) /Pr~ (3+) fluorescence film, when the doping concentration of Pr~ (3+) is less than 0.75%, the intensity of the luminescence spectrum can still remain above 95%. The first prepared Y0.7Gd0.3AG:3.3%Ce~ (3+), the 0.5%Pr~ (3+) fluorescent film red shift to the 550 nm, the sharp red emission peak in the 611 nm, its luminescence spectral intensity relative to Ce~ (3+) has also been improved. The performance of the encapsulated white light LED is improved, the luminescence efficiency is 84 lm/W, the color rendering index is 83.4, the color temperature is 4327 K.6., and the Co doped energy transfer sensitizer is used to enhance the absorption ability of the fluorescence film to the stimulated luminescence. The transition is 4f to 5D Tb~ (3+), and the prepared YTb AG:5%Eu~ (3+) and YTb AG:3.3%Ce~ (3+) have a super absorption peak in the ultraviolet region. Therefore, under the condition of 275 nm excitation, the luminescent spectral intensity of the prepared fluorescent film is enhanced under the action of energy transfer. Green light emission; YTb AG:x%Eu~ (3+) fluorescence film has a controllable luminescence performance. With the increase of 5% of Eu~ (3+) concentration from 0%, the luminescence can change from green light to Huang Lvguang, yellow, orange, orange, red and red light.
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN104.3;TN312.8

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