基于LED应用的掺氮变色长余辉荧光粉的制备与发光调控研究

To meet application requirements of the important new generation of light source of LED. The investigation on orange and red phosphors with excellent performance and easy preparation has become the international advancing spot. Enhancing the luminous efficiency of the orange and red phosphors and introducing the long persistence property are till the key scientific problems of international concern. Hence, this project is intended to explore nitrogen-doping phosphor materials by flux method, analyze the preparation conditions for effectively controlling the particle morphology, and obtain the approach for reducing the preparation temperature; improve the luminescence thermal stability by doping nitrogen in phosphors and reveal the immanent mechanism of phosphor’s emission wavelength red-shift which is caused by the nephelauxetic effect of nitrogen doping by analyzing the variety of the quantum efficiencies for different doped samples, subsequently obtain the efficient orange and red emissions with the help of Eu2+-Mn2+ energy transfer; introduce the long persistence property by “color-variety” way, and investigate the underlying long persistence mechanism and color-variety characteristics by the thermoluminescence spectra, persistence lifetime and chromaticity coordinate; clarify the internal process of the energy transfer between the luminescent ions by combining the electronic structure calculation of the first principle, illustrate the relationship of the spectral band red-shift and the preparation conditions design. By introducing color-variable long persistence into the common phosphors for LED innovatively, it can not only meet the requirement of solid-state lighting but also provide the emergency lighting, which largely develops the application potential and prospect for LED lighting.

为满足新一代重要照明光源LED的应用，性能优良且制备简便的橙、红光发射荧光粉的研究已成为国际前沿，而有效提升橙、红色荧光粉的发光效率并引入长余辉特性仍是国际关注的关键科学问题。本项目将通过助熔剂法制备含氮荧光粉材料，分析有效调节颗粒形貌的制备条件，获得降低其合成温度的途径；以氮掺杂提高荧光粉发光热稳定性，并针对不同掺杂样品量子产率的变化及荧光光谱特征揭示氮掺杂引起的电子云重排使荧光粉发射波长红移的内在机理，随后借助发光离子间的能量传递获得高效橙、红光发射；以“变色”方式引入长余辉性能，通过热释光谱、余辉时间与色坐标探究深层余辉机理与变色特点；理论上结合第一性原理的电子结构计算弄清发光离子能量传递的内在过程，阐明光谱带红移与材料制备设计的关联。本项目最终在常规LED用荧光粉基础上创新性地引入变色长余辉，不仅满足LED光源普通照明需要，也能满足应急照明要求，极大提升LED照明的应用潜力和前景。

本项目针对新一代照明光源LED的广泛应用，重点开发系列氮掺杂长余辉荧光粉等发光材料，不仅可满足LED光源普通照明需要，也能满足应急照明要求，极大提升LED照明的应用潜力。首先，对于硅酸盐长余辉荧光粉，开发了Sr2MgSi2O7-1.5xNx:Eu2+,Dy3+、Sr3MgSi2O8-1.5xNx:Eu2+,Dy3+,Mn2+和Ca2MgSi2O7−1.5xNx:Eu2+,Dy3+三类材料，其发光亮度和余辉时间可通过改变N掺杂浓度进行调控，利用N对O的不等价取代获得利于长余辉性能的晶体缺陷，并以热释光谱等进行详细解释；在Sr2MgSi2O7-1.5xNx:Eu2+,Dy3+与Ca2MgSi2O7−1.5xNx:Eu2+,Dy3+制备中添加2wt%的H3BO3助熔剂，在Sr3MgSi2O8-1.5xNx:Eu2+,Dy3+,Mn2+制备中添加1.5wt%的H3BO3助熔剂，均获得了表面光滑的颗粒，其平均粒径在10μm以内，可达到应用要求。其次，研究中还发现一些长余辉性能不明显或无长余辉性能的新型硅酸盐基LED用发光材料，主要有Ca2Gd8(SiO4)6O2:Ce3+,Tb3+,Mn2+、Ca5Y3Na2(PO4)5SiO4F2:Eu2+,Tb3+,Mn2+、Ba2Gd2Si4O13:Ce3+,Eu2+,Sm3+、Ca7(PO4)2(SiO4)2:Eu2+、LiY9(SiO4)6O2:Ce3+,Tb3+,Sm3+及Ca9La(PO4)5SiO4F2:Eu2+,Mn2+等，研究其不同发光离子间的能量传递作用，包括Eu2+-Mn2+、Tb3+-Mn2+和Ce3+-Tb3+等，并用衰减曲线及发光光谱进行验证，用能级示意图解释能量传递过程；通过控制能量传递效率实现发光颜色可调，并在一些荧光粉中实现白光发射；通过LED器件的封装，评估其应用潜力，如将开发的蓝色Ca7(PO4)2(SiO4)2:Eu2+荧光粉和目前商用绿色与红色荧光粉相复合，以365nm的LED芯片作为激发光源，封装成的LED器件具有高亮度、低色温及优异的显色指数。再次，开发了一些磷酸盐基的LED用发光材料，如Sr1-nBanMg2(PO4)2:Ce3+,Eu2+,Na+、Ca9.3Mg0.7K(PO4)7:Eu2+,Tb3+,Mn2+及K3Y(PO4)2:Tb,Eu等，并研究了其多色化发光特征。