白光LED用红粉薄膜复合荧光玻璃的制备及性能研究

发布时间：2019-01-04 20:06

【摘要】：作为第四代照明光源,白光LED因节能环保、寿命长、使用电压低、响应快等优点,在室内外、特种照明领域受到广泛应用。常见的商用白光LED是用硅胶或环氧树脂包YAG:Ce3+荧光粉后直接涂覆在蓝光InGaN芯片上制成的。然而,这种封装方式存在三个问题:1)由于传统有机封装材料的热导率太差,在长时间热辐射的工作环境中容易老化、黄化,导致LED光衰、色坐标偏移,降低了其使用寿命;2) YAG:Ce3+荧光粉颗粒折射率与有机封装材料折射率不匹配,同样会导致光散射损失。3) YAG:Ce3+荧光粉发射光谱中红光成分不足,封装成的白光LED器件显色指数偏低、色温偏高使其难以得到暖白光。因而,具有热导率高、结构稳定、光输出性能良好且兼有显色指数、色温可调等特性的新型光学材料正成为半导体照明技术研究的热点。本课题开创了红粉薄膜复合荧光玻璃的组合方式:即首先制备出热/化学稳定性良好、光学性能优异的荧光玻璃(微晶玻璃),再采用丝网印刷的方式涂覆一层红粉薄膜在荧光玻璃片上封装成白光LED期间。这种复合方式既结合了玻璃优良的导热性能、较好的光透过性、物化性能稳定等优点,克服了传统白光LED寿命短、折射率不匹配等缺点;又采用了丝网印刷法涂覆红粉的方式实现了白光LED的色度可调。主要的研究内容如下:(1)在前期实验的基础上,采用一步低温共烧结法首先制备了透明的LuAG:Ce3+荧光玻璃,再采用丝网印刷的方式涂覆1113相的CaAlSiN3:Eu2+封装得到白光LED器件。首先制备的LuAG:Ce3+荧光玻璃利用XRD、SEM、荧光光谱等方式表征了样品的物相、微观结构及发光性能,并且热稳定性测试结果显示LuAG:Ce3+在同等条件下荧光强度明显高于硅胶封装的LuAG:Ce3+,表明一步低温共烧结法能很好的制备出导热性能优良、光透过性较好、物/化性能稳定的荧光玻璃。切割成片的荧光玻璃片与蓝光芯片复合封装成LED器件,无论是改变掺杂的荧光粉浓度还是荧光玻璃片的厚度都很难获得暖色调的白光。随后,采用丝网印刷的方式将CaAlSiN3:Eu2+红粉薄膜均匀的涂覆在切割成片的LuAG:Ce3+荧光玻璃衬底上,封装成的LED器件色度随红粉含量的变化白光由冷白光到正白光后到暖百光区域移动,相应的光电参数色温降低、显指上升。且同等条件下,表面涂覆红色荧光层的荧光玻璃其荧光强度与未涂覆比较只发生了微弱的变化,进一步表面这种复合红粉薄膜和荧光玻璃方式可以应用用大功率LED室内照明。最后其封装的器件的空间色度分布较差,未来有待进一步研究。(2)同样,用一步低温共烧结法首先制得透明的YAG:Ce3+,Ga3+ (YAGG)荧光玻璃,再利用丝网印刷的方式涂覆258相Ca2Si5Al8: Eu2+红色粉薄膜YAGG衬底上封装得到LED器件。制备的YAGG荧光玻璃同样通过XRD、SEM、荧光光谱等方式表征了样品的物相、微观结构及发光性能,表明了 YAGG同LuAG:Ce3+一样在该玻璃基质中保持了较好的物化、光学稳定性。随后,采用丝网印刷的方式将红粉薄膜均匀的涂覆在切割成片的YAGG荧光玻璃。研究了不同红粉浓度和涂覆厚度对于红粉薄膜的光学、热稳定性从而找到最佳涂覆厚度,在最佳涂覆厚度上改变红粉浓度使得封装的LED器件色度由冷白光到正白光后到暖百光区域变化,相应的光电参数色温降低、显指上升。最后,我们对此封装的LED器件进行了热、湿稳定性的测试研究,实验结果显示,经过热冲击和长时间的湿侵蚀,荧光强度损失低(小;于于g%),显指和色温变化很小,充分表明了这种红粉薄膜复合荧光玻璃材料具有良好的可靠性,可应用于大功率长时间的LED照明。
[Abstract]:As the fourth-generation illumination light source, the white light LED has the advantages of energy conservation, environmental protection, long service life, low use voltage, fast response and the like, and is widely applied in the field of indoor and outdoor and special illumination. The common commercial white light LED is made of silica gel or epoxy resin bag YAG: Ce3 + fluorescent powder and is directly coated on the blue-light InGaN chip. however, there are three problem in this encapsulation mode: 1) because that thermal conductivity of the conventional organic packaging material is too poor, it is easy to age and yellow in the working environment of long-time heat radiation, resulting in an LED light attenuation, a color coordinate shift, a reduced service life thereof, and 2) a YAG: and the refractive index of the Ce3 + fluorescent powder particles does not match the refractive index of the organic packaging material, and the light scattering loss is also caused. 3) the red light component in the YAG: Ce3 + fluorescent powder emission spectrum is not enough, the color rendering index of the packaged white light LED device is low, and the color temperature is high, so that the white light is difficult to obtain. therefore, the novel optical material with the characteristics of high thermal conductivity, stable structure, good light output performance and both color rendering index and color temperature adjustment is becoming a hot point for the research of the semiconductor lighting technology. The method for combining the red powder and the composite fluorescent glass comprises the following steps of: firstly, preparing a fluorescent glass (microcrystalline glass) with good thermal/ chemical stability and excellent optical property, and coating a layer of red powder film on the fluorescent glass sheet in a screen printing mode to form a white light LED. The composite mode not only combines the advantages of excellent heat conductivity of the glass, good light transmittance, stable physical and chemical property, and the like, overcomes the defects of short service life of the traditional white light LED, does not match the refractive index, and the like, and realizes the chromaticity adjustment of the white light LED by adopting a screen printing method to coat the red powder. The main research contents are as follows: (1) The transparent LuAG: Ce3 + fluorescent glass is prepared by one-step low-temperature co-sintering method on the basis of the earlier experiment, and the white light LED device is obtained by coating 1113-phase CaAlSiN3: Eu2 + in screen printing. The first prepared LuAG: Ce3 + fluorescent glass characterized the phase, microstructure and luminescence of the sample by means of XRD, SEM and fluorescence spectra, and the results of the thermal stability test show that the fluorescence intensity of the LuAG: Ce3 + under the same conditions is obviously higher than that of the LuAG: Ce3 + of the silica gel package. It is shown that the one-step low-temperature co-sintering method can produce the fluorescent glass with excellent thermal conductivity, good light transmittance and stable object/ chemical property. the fluorescent glass sheet and the blue-light chip which are cut into pieces are combined and packaged into an LED device, so that the white light of the warm color is difficult to be obtained by changing the concentration of the doped fluorescent powder or the thickness of the fluorescent glass sheet. then, the CaAlSiN3: Eu2 + red powder film is uniformly coated on a sheet-shaped LuAG: Ce3 + fluorescent glass substrate in a screen-printing manner, and the chromaticity of the packaged LED device changes with the change of the red powder content from the cold white light to the warm white light area, the color temperature of the corresponding photoelectric parameter is reduced, and the color temperature of the corresponding photoelectric parameter is raised. and under the same conditions, the fluorescence intensity of the fluorescent glass with the red fluorescent layer coated on the surface is slightly changed compared with the uncoated comparison, and the further surface of the composite red powder film and the fluorescent glass can be used for lighting in a high-power LED. Finally, the space chromaticity distribution of the packaged device is poor, and the future is to be further studied. (2) in the same way, the transparent YAG: Ce3 +, Ga3 + (YAGG) fluorescent glass is first prepared by one-step low-temperature co-sintering method, and the 258-phase Ca2Si5Al8: Eu2 + red powder film YAGG substrate is coated on the YAGG substrate by screen printing to obtain the LED device. The prepared YAGG fluorescent glass is also characterized by XRD, SEM and fluorescence spectra, and shows that YAGG has better physical and chemical and optical stability in the glass matrix, like LuAG: Ce3 +. Subsequently, the red powder film was uniformly coated on a cut sheet of YAGG fluorescent glass in a screen-printing manner. the optical and thermal stability of the different red powder concentration and the coating thickness on the red powder film are studied so as to find the optimal coating thickness, change the concentration of the red powder on the optimal coating thickness so that the chromaticity of the packaged led device is changed from the cold white light to the warm white light after the white white light to the white white light, the color temperature of the corresponding photoelectric parameter is reduced, and the color temperature of the corresponding photoelectric parameter is raised. In the end, we tested the heat and wet stability of the LED device in this package, and the results show that the fluorescence intensity loss is low (small; in g%) after thermal shock and long-time wet erosion, and the change of color temperature and color temperature is small. The red-powder thin-film composite fluorescent glass material has good reliability and can be applied to high-power long-time LED illumination.
【学位授予单位】：温州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ171.1

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