白光LED用长效Sr2SiO4:Dy3+/低熔点玻璃荧光复合材料的设计及发光性能研究

The bad light decline of phosphors for white LEDs due to the much heat from the working high-power LED chip are solved by designing and preparing the novel single host phosphor/ low melting point glass composite materials and investigating its luminescence properties in this project..The single host and single luminescence center Sr2SiO4:Dy3+ phosphors with controlled crystal form and particle size distribution are prepared by solid state reaction with flux are prapared and the mechanism of phase transition is clarified..To solve the decreased luminescence efficiency resulted from the reabsorption between R-G-B colors excited by UV-LED, the high-efficiency phosphors for white LEDs are obtained by selecting specific sensitization ions to enhance its luminescence intensity and broaden its excitation range. .Based on the calculation of the properties of phosphate glass by thermodynamic software such as the coefficient of heat conductivity, the thermal expansion coefficient and melting point, the low melting point glass substrate powders with high thermal conductivity and matching thermal expansion coefficient are prepared by adjusting the ratio of compositions and optimizing the preparation technology..The high stability and long life luminescence materials for white LEDs are designed and prepared by combining the new phosphor and glass substrate based on the investigation of the influence of the composition and structure of the interface of the composite materials on the luminescence properties and the regulatory mechanism of the composition and interface, and the theoretical guidance of is provided for their application in white LEDs.

通过新型单基质白光LED荧光粉/低熔点玻璃复合荧光材料的设计、制备及发光性能研究，解决由于环氧树脂导热能力差使得大功率LED芯片产生大量热量无法散出，导致荧光粉发生严重光衰的问题。引入NH4Cl助熔剂制备组成、晶型、粒度可控的Sr2SiO4:Dy3+荧光粉，揭示Sr2SiO4:Dy3+在NH4Cl助熔剂作用下的相变规律，掺杂Bi3+、Ce3+等敏化离子，拓宽Dy3+激发范围，提高发光强度，获得高发光性能的Sr2SiO4:Dy3+荧光粉；借助热力学计算硼磷酸盐玻璃体系的导热系数、热膨胀系数、熔点等性能参数，实验优化其组分配比，制备高导热、低熔点玻璃基体粉体；将荧光粉和玻璃基体相结合，研究复合材料组成、结构及工作温度下的界面特性对发光性能的影响规律，阐明界面调控机制，设计并制备白光LED用长效、高发光性能Sr2SiO4:Dy3+/低熔点玻璃荧光复合材料，为其在白光LED中的应用提供理论指导。

通过新型单基质白光LED荧光粉/低熔点玻璃复合荧光材料的设计、制备及发光性能的研究，解决由于环氧树脂导热能力差使得大功率LED芯片产生大量热量无法散出，导致荧光粉产生严重光衰的问题。本项目首先引入NH4Cl助熔剂制备了晶型、粒度可控的Sr2SiO4:Dy3+荧光粉，并采用热力学计算和分别以NH4Cl与SrCl2为助熔剂制得样品的性能比较，验证了NH4Cl在固相反应形成Sr2SiO4过程中的作用机理：NH4Cl在低温阶段热分解的HCl与SrCO3反应生成SrCl2，SrCl2作为助熔剂一方面降低了碳酸盐原料的分解温度，另一方面通过形成液相加速了Sr2SiO4相的形成。同时，掺杂Bi3+、Ce3+等敏化离子，通过电多极相互作用的增敏作用，Dy3+的发光强度提高了2~3倍。借助热力学计算硼磷酸盐玻璃体系的导热系数、热膨胀系数、熔点等性能参数，最终确立了最佳的高导热低熔点玻璃基体组成为50P2O5-10B2O3-30BaO-10Li2O。采用两步烧结法将高发光性能的(Sr0.99Dy0.01Li0.01)2SiO4荧光粉与高导热、低熔点玻璃基体50P2O5-10B2O3-30BaO-10Li2O玻璃混合并烧结，制备了长效、高发光性能玻璃荧光复合材料，研究了荧光粉含量及热处理温度对玻璃荧光复合材料的性能影响规律。增加荧光粉含量使得发光强度提高，但使烧结性能变差；升高热处理温度促进烧结致密，但发光性能有所降低。为平衡烧结性能和发光性能，玻璃荧光复合材料最佳组成配比为荧光粉：玻璃粉=1：1（wt%），在510℃下保温4h制备的玻璃荧光复合材料具有最佳性能，在白光LED领域具有良好地应用前景。

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