BN包覆碱土金属硫化物红色荧光粉的原位同步合成及性能研究

Traditional alkaline earth sulfides (AES) such as MS:Eu2+(M=Mg, Ca, Sr, Ba) have long been known as versatile red-emitting phosphor materials. Nowadays, AES have been considered to be one of the most promising candidates for white LED applications due to its strong absorption in the blue region that is suitable to blue LED pumping. The red-light emission plays an important role in improving the color temperature and color rendering index of the white light. However, the low chemical stability of AES hinders its real utilization in white LED applications. This project aims to develop stable AES-based phosphors by surface modification using an ultimately chemically stable and optically transparent BN sheath. A one-step in-situ method will be developed to synthesis uniform BN-sheathed AES-based red-emitting phosphors. The chemical stability and photoluminescence properties of the BN-sheathed phosphors will be studied, and the coating mechanism, as well as the effect of BN coating on the stability and photoluminescence properties of AES phosphors will be clarified. It is anticipated that the successful coating of AES with homogeneous BN sheath will lead to the stable and high efficient AES based red-emitting phosphors forming. The expected outcomes will provide an effective strategy to overcome current phosphor stability problems, and will meet the urgent demand upon the superior red-emitting phosphors for white LED applications.

碱土金属硫化物体系荧光粉是一类传统的高效红色荧光材料，单从光谱性能方面来说，非常适合在基于蓝光芯片的白光LED中得到应用，起到调制色温以及改善显色性的功能。然而由于碱土金属硫化物的化学稳定性较差，导致了这类荧光粉的应用受到了极大的限制。结合当前的研究进展和本课题已有的研究基础，本项目拟选择具备优良化学惰性和透光性能的六方BN作为硫化物荧光粉的保护层，建立和发展一条通用的BN包覆碱土金属硫化物体系的同步合成方法，实现对荧光粉的均匀致密包覆，并进一步研究包覆产物的化学稳定性和发光特性，阐明BN包覆的机理及其对荧光粉性能的影响，预期得到具有良好稳定性、较高量子效率的白光LED用红色荧光粉材料。本项目的实施，顺应了白光LED照明对红色荧光粉的性能的迫切要求，拟获得的研究成果将能够解决硫化物红色荧光粉稳定性较差的难题，为其进一步在高显色性白光LED方面的应用奠定基础。

本项目按照申请书和计划书的研究计划，完成了研究内容，达到了预期目标，取得的主要研究成果如下：（1）研究了一维BN包覆的Ca1-xSrxS:Eu纳米线的制备及发光性能调控，通过调节Ca1-xSrxS纳米线的成分以及采用Ce和Eu稀土离子共掺杂的方法来实现对其红色发光的峰位和强度的控制，制备的BN包覆的Ca1-xSrxS:Eu纳米线有望应用在纳米光电器件和荧光粉转换白光LED等方面；（2）合成了BN包覆的CaS:Eu纳米线，通过与未经BN包覆的CaS块材做对比，详细研究了产物的化学稳定性和光稳定性，结果证实，BN包覆层有效地提高了CaS:Eu纳米线的化学稳定性，并且在电子束辐照下也保持了较稳定的发光性能。（3）采用不同元素掺杂制备了BN包覆的CaS:Ce和CaS:Dy纳米线并研究了其发光性能，这种多色发光的CaS纳米线有望在多色荧光标记、全彩显示屏、白色发光以及电致发光器件等方面得到应用。（4）将活性BN作为载体，合成了罗丹明B和异硫氰酸荧光素负载的BN复合荧光粉体系（(RhB & FITC)/BN）并研究了其性能，合成的复合荧光粉相对于纯的有机荧光染料表现了更好的热稳定性和光稳定性；（5）将(RhB & FITC)/BN复合荧光粉与环氧树脂混合并封装蓝光LED芯片，得到了(RhB & FITC)/BN基白光LED器件，表现出优良的光学特性：发光光谱色坐标为（0.32，0.34），发光效率为21.6 lm/W，高电流稳定性（达到60 mA）。本项目研究成果发表SCI论文18篇，申请发明专利2项，培养博士生3名，硕士生2名。