有机给体/稀土纳米晶复合荧光材料应用于白光LED探索

The white LED is a new generation of lighting source,high-performance phosphor matched with LED is to determine the key technology of the LED lighting.The traditional inorganic LEDs rare earth phosphor still has problems such as the limitations of the matching between the phorphos and the LED chip,the poor chroma of the LED device etc.The project is proposed to solve the lack of traditional LED phosphor via organic donor and rare earth nanocrystalline composite,that is, efficient fluorescence can be realized by the energy transfer from controllable the surface organic dornor which has high efficient absorption to the rare earth nanocrystals.We intend to adopt a non-aqueous phase method to make Y2O3:Eu3+,YPO4:Tb3+,LaPO4:Tm3+.High performance tricolor rare earth nanocrystalline materials, and do the surface passivation to form nanocomposite by acac and azobenzene organic ligands.Deep study the effects of size, structure, morphology of rare earth nanocrystalline， the molecular orbitals of organic ligands and the thickness of organic passivation layer on emission and excitation bands, luminescence dynamics and the quantum yield of the emission.Reveal interface effects on the energy transfer process.Optimize and obtain high-performance UV and blue excitation LED phosphor.Package high brightness and high chroma new white LED devices, and break through the monopoly of foreign technology.

白光LED是新一代照明光源，与之相匹配的高性能荧光粉是决定LED照明的关键技术；目前传统无机LED稀土荧光粉还存在荧光粉与芯片匹配局限和色度不佳等问题。本项目提出利用有机给体和稀土纳米晶的复合解决传统LED荧光粉的不足：即通过表面有机给体的可控与高效吸收，将激发能量有效传递给稀土纳米晶荧光材料，实现高效的荧光发射。拟采用非水相法合成Y2O3:Eu3+、YPO4:Tb3+、LaPO4:Tm3+等高性能三基色稀土纳米晶材料，并以acac和azobenzene等有机配体对其进行表面钝化形成复合材料；深入研究材料中稀土纳米晶的尺寸、结构、形貌，和有机配体的分子轨道、钝化层厚度对发射与激发谱带的调控作用；研究这些因素对材料的荧光动力学过程和发光效率的影响，揭示介面配位与能量传递过程的关系；优化并获得高性能的紫外和蓝光激发LED荧光粉，封装制备出高亮度与高色度新型白光LED器件，以突破国外技术垄断。

在本项目中，我们着重的研究了稀土纳米晶与有机给体、贵金属等在上转换荧光增强方面的研究，重点是如何改进复合结构，以及探索可用于白光LED的上转换发光材料结构与界面耦合的物理实质，通过研究具有反蛋白石结构的稀土纳米晶复合荧光材料的制备与掺杂稀土离子发光调制，进而提高稀土纳米晶材料的荧光强度。对Yb3+和Er3+共掺杂不同声子能的Y2O3、GdVO4、NaGd(WO4)2基质材料进行了系统的机理研究和分析，结论说明我们可以通过寻找合适声子能的基质材料来获得高效的上转换发光材料，进而应用于未来的白光LED、太阳能光伏电池以及生物成像治疗等方面；同时我们也证明了荧光上转换增强主要来源于激发电磁场的表面等离子耦合。最后，基于表面等离子体增强荧光上转换在指纹识别、防伪打印等方面的应用得以实现，这也为金属/上转换复合体系提供了一个新的应用前景。