用于白光LED的Eu(II)激活磷酸盐单一基质白光发光材料的设计合成与光谱调控

White light-emitting diodes (WLEDs) are promising for new generation solid-state lighting in 21 century because of their advantages of high luminous efficiency, energy savings, long lifetime, good reliability and safety and environmental protection. However, there are some shortcomings of single-phased white-light-emitting phosphors applied to WLEDs, such as low luminous efficiency, bad color rendering index (CRI) and high sintering temperature. In view of the above shortcomings, Eu2+ activated single-phased white-light-emitting phosphor with special structure will be designed and synthesized instead of combination of red, green and blue. We get started with two aspects: (i) choose phosphates as the research host for their low synthesis temperature, high luminous efficiency and high stability and (ii) select Eu2+ as activator since the emission wavelength of Eu2+ is strongly dependent on the crystal field. It is expected that Eu2+ can occupy different sites in phosphate lattices, which lead to the unresolved broad emission spectra. We will systematically investigate the influence of crystal field on luminescence properties and the luminescence mechanism of upon near-ultraviolet light (NUV) excitation. Besides, the rule of selecting single-phased white-light-emitting phosphors suitable for used in NUV WLEDs will be summarized. It will provide theoretical basics for developing cosmically and purposefully novel single-phased white phosphors with high luminous efficiency, energy savings and environmental protection to be applied in WLEDs.

白光LED具有发光效率高、节能、寿命长、稳定性好、绿色环保等显著优点，被认为是21世纪最有价值的新光源。本课题针对目前白光LED用单一基质白光发光材料发光效率低、显色指数差和烧结温度高等缺点，依据Eu2+的电子构型和发光特点，以Eu2+为激活离子，通过设计具有特殊结构的基质材料，来实现发光材料白光发射的单一基质化。重点研究可以促使Eu2+在基质晶格中占据不同晶体格位，且烧结温度低、发光效率高、稳定性好的磷酸盐体系，探讨晶体结构对其发光性质的影响规律，并实现对Eu2+发射光谱的调控，研究近紫外光（NUV）激发下荧光粉的发光机理，总结归纳适用于LED的白光荧光粉基质的选择规律，为大规模、有目的地研制高光效，低能耗，无污染的优质白光LED用单一基质白光发光材料提供指导依据。

本项目依据课题研究计划和研究目标，针对性地开展了研究工作，取得了以下主要研究进展：1）开展了具有不同阳离子取代格位的多磷酸盐荧光粉的设计合成与探索：成功研制了Sr5Cl0.75F0.25(PO4)3: Eu2+等10余种类型的多磷酸盐荧光粉，筛选出具有明显不同发射带的荧光粉，为调控荧光粉发射光谱及研制单一基质白光发光材料提供了可靠的保证；2）开展了单一基质白光发光的多磷酸盐发光材料设计合成及光谱调控研究：采用晶相设计策略，成功实现了Ba3P4O13基质由低温相向高温相的转变，调控了Eu2+在Ba3P4O13不同晶相中的比例，荧光粉的发光颜色由蓝光变为白光最终变为黄光，最终获得了单一基质白光荧光粉Ba3P4O13:Eu2+，为通过晶相转变实现荧光粉的光致发光调控，进而实现单一基质白光荧光粉提供了一种新的设计理念和成功范例；3）拓展开展了多种激活离子共掺杂的单一基质白光荧光粉的设计合成及性能研究：设计合成了Eu2+/Eu3+和Tb3+共掺杂的Ca9NaZn(PO4)7荧光粉，成功地实现了还原气氛下荧光粉体系中不同晶格位置的Eu2+/Eu3+的掺杂浓度比的调控，获得了单一基质白光荧光粉，这为通过结构设计调控Eu2+/Eu3+在不同晶格中的占比，实现单一基质白光荧光粉提供了一种新的理念和途径； 4）拓展开展了其他体系，如：硼酸盐体系，硅酸盐体系发光材料的研究：研究表明这些荧光粉在白光LED中都有潜在的应用价值，这些有益的拓展研究与探索为通过光谱调控实现单一基质白光发光材料提供了更加广阔的研究思路。项目执行期间共计发表论文17篇（其中SCI收录JCR一区论文8篇，二区论文5篇，影响因子大于3.0的论文8篇，论文总被引用次数107次，单篇最高被引25次）；撰写英文专著1个章节；申请国家发明专利6项；应邀参加国际国内会议3次，做邀请报告3人次；培养8名硕士生取得硕士学位。