颜色可调稀土双掺杂氮化物发光材料及其转换的暖白光LED

White LED ( light emitting diode ) is going to govern the solid state lighting for the next generation.The warm white LED is paid more attention because it can provide warm and comfortable feeling and safe traffic at night. Using phosphor to convert blue light of LEDs into white light is the main method to generate white light for present white LEDs.The widely used yellow emitting YAG:Ce phosphors lack enough red components.To achieve warm white light, red emitting phosphors such as Eu2+ activated nitrides are needed to mix with the yellow one, however leading to low converting efficiency and color point shift.This project attempts to achieve a unblended,single phosphor with enough red luminescence and it converted warm white LED. Basing on our previous research work, we propose to codope Ce3+ into Eu2+ activated SrAlSi4N7 red phosphor to form rare earth ion doubly doped material:SrAlSi4N7:Ce3+/Eu2+. It is expected that emitting color tuning between yellow and red is performed and consequently warm white light is obtained. In this project, the study will be focused on dependence of emission spectral distribution on Ce3+/Eu2+ concentrations, optimizing of material compositions and prepartion conditions and then encapsulation of warm white LEDs. The present project is significant for forming our self-owned LED phosphors and LED devices, and also for pushing our creative study of solid state lighting.

白光LED将主导下一代固态照明，而暖白光LED能够提供更温暖、舒适和交通更安全的照明，更受青睐。利用荧光材料转换是当前白光LED采用的主流技术，广泛应用的YAG:Ce黄色荧光材料红光成分不足，为获得暖白光需混合Eu2+激活的氮化物红色荧光材料，存在效率低和颜色漂移问题。本申请旨在研制一种非混合型的、红色成分丰富的单一基质荧光材料及其转换的暖白光LED。在前期研究工作基础上提出，在Eu2+激活的氮化物SrAlSi4N7红色荧光材料中再引入黄色发光中心Ce3+形成稀土双掺杂氮化物SrAlSi4N7: Ce3+/Eu2+，以期实现发光颜色在黄色和红色之间连续调节，获得暖白光。研究发射光谱分布与Ce3+/Eu2+浓度的依赖关系，优化材料组分和制备条件，封装暖白光LED。本项目对于形成具有自主知识产权的LED荧光材料与器件技术，促进我国固态照明的创新研究具有重要意义。

白光LED将主导下一代固态照明，而暖白光LED能够提供更温暖、舒适和交通更安全的照明，更受青睐。利用荧光材料转换是当前白光LED采用的主流技术，通常利用黄色荧光粉和红色荧光粉的混合获得暖白光，但存在效率低和颜色漂移问题。本项目在研制一种非混合型的、红色成分丰富的单一基质荧光材料及其转换的暖白光LED。研制出Ce3+/Eu2+双掺杂SrAlSi4N7氮化物新型荧光粉，光谱由Ce3+的黄色发射带和Eu2+的红色发射带构成，通过控制Eu2+的掺杂量，材料发光波长可从原来的550 nm连续调节到610 nm，伴随发光颜色从黄色到红色的变化。发现发射波长比商用荧光粉YAG:Ce的更长，发光带更宽，适合应用于高显色性白光LED。发现存在两种Ce3+格位和一种Eu2+格位，这两种格位的Ce3+都向Eu2+发生能量传递，从而实现了光谱的有效调控。利用该发光材料，封装了系列白光LED，获得了显色指数高达88的暖白光器件。还研究了Ce3+/Mn2+双掺杂CaO白光荧光粉，光谱由Ce3+的黄色发射带和Mn2+的红色发射带构成。观察到Ce3+向Mn2+的能量传递，随Mn2+浓度的提高，发光颜色从当初的黄色逐渐向红色转变，最后完全变成红色。实验发现，当Mn2+浓度为0.02时，能量传递效率已达 94 %；说明CaO中Ce3+向Mn2+的能量传递是非常有效的。确定出CaO中Ce3+-Mn2+能量传递临界距离为10.5 Å。 利用制备的荧光粉封装了白光LED， 得到显色指数较高为83，色温为3973K的暖白光LED。本项目发表SCI论文31篇，申请或授权中国发明专利9项。项目完成了预期技术指标，本项研究对于形成具有自主知识产权的LED荧光材料与器件技术，促进我国固态照明的创新研究具有重要意义。