近紫外激发白光LED用Bi3+掺杂荧光粉的关键科学问题研究

The combination of near ultraviolet (380-410nm) LED chip and multiple phosphors is one of key approaches towards white light LEDs. To avoid the reabsorption between phosphors, which will lower the overall efficiency of device, the phosphors for this approach should be excitable by near ultraviolet rather than visible lights. Current rare earth doped phosphors cannot fully meet the demand. Our previous works, however, have shown that Bi3+ doped phosphors are very promising to meet the requirements. But there are problems for the phosphors such as weak absorption in near ultraviolet or degradation etc. So far, there have been no systematic works as well as solutions on these key scientific problems. This project will center on Bi3+ doped phosphors and strive to solve the problems. For that, we are planning to first synthesize all kinds of Bi3+ phosphors systematically with proper covalence. This will allow us to explore new bismuth activated phosphors in one hand, and in the another to investigate the influences of host types, covalence, coordination environments around bismuth such as symmetry, coordination number etc on the energy levels of bismuth 6s6p configuration, excitation transition probability, emission peaks, quantum efficiency etc, respectively. From these, we try to better understand the law of bismuth luminescence. We are also going to study the influences of temperature, moisture, work atmosphere, irradiation of near ultraviolet on the evolution of phosphor morphologies, chemical composition, crystalline phases, bismuth valence and luminescence properties etc, respectively. These studies will help to unravel how degradation comes into being and it will help definitely to find the solutions to suppress degradation. On basis of the law of bismuth luminescence and degradation mechanism, we are going to enhance the absorption in near ultraviolet by for instance composition design, to overcome degradation by modification of phosphor particle surfaces etc, and optimize the synthesis procedures, and eventually achieve high performance bismuth doped phosphors as well as prototype of white light LED devices with a prospect of commercial application.

近紫外(380-410nm)LED芯片结合多色荧光粉是获得白光LED的重要方案之一。为克服粉间再吸收，方案要求荧光粉在近紫外有激发、在可见无激发。目前稀土荧光粉无法完全满足本要求。前期研究表明Bi3+掺杂荧光粉有望满足这种要求，但其存在近紫外吸收弱、光衰等问题，目前对这些关键科学问题及解决办法尚无系统研究。本项目拟以Bi3+掺杂荧光粉为研究对象，着力解决这些问题。拟系统合成各种共价性适中的掺铋化合物，探索新荧光粉，研究基质类别、共价性、配位环境如格位对称性等对铋6s6p组态能级位置、激发跃迁几率、发射峰、量子效率等影响，掌握铋发光规律，研究温度、湿度、氛围、近紫外辐照等对样品形貌、化学组成、晶相、铋价态及发光性质等影响，揭示光衰机制，依据铋发光规律与光衰机制，通过组成设计等增强近紫外吸收，通过颗粒表面修饰等克服光衰，通过合成工艺优化，最终获得可产业化的高性能铋荧光粉及其白光LED原型器件。

近紫外(380-410nm)LED芯片结合多色荧光粉是获得白光LED的重要方案之一。为克服粉间再吸收，方案要求荧光粉在近紫外有激发、在可见无激发。目前稀土荧光粉无法完全满足本要求。前期研究表明Bi3+掺杂荧光粉有望满足这种要求，但其存在近紫外吸收弱、光衰等问题，目前对这些关键科学问题及解决办法尚无系统研究。本项目拟以Bi3+掺杂荧光粉为研究对象，着力解决这些问题。拟系统合成各种共价性适中的掺铋化合物，探索新荧光粉，研究基质类别、共价性、配位环境如格位对称性等对铋6s6p组态能级位置、激发跃迁几率、发射峰、量子效率等影响，掌握铋发光规律，研究温度、湿度、氛围、近紫外辐照等对样品形貌、化学组成、晶相、铋价态及发光性质等影响，揭示光衰机制，依据铋发光规律与光衰机制，通过组成设计等增强近紫外吸收，通过颗粒表面修饰等克服光衰，通过合成工艺优化，最终获得可产业化的高性能铋荧光粉及其白光LED原型器件。