白光LED用量子点/荧光粉耦合调控及其封装机理研究

In order to improve the color rendering index of the white LED, the approach of using the quantum dots as a color complement of the white LED draws a lot of interests in the solid illumination field. However, it suffers from the drawback of low luminous efficiency of the white LED owing to the lower luminous efficiency of the quantum dots. To solve these problems, we plan to use Au nano-particles to couple into core/shell quantum dots/phosphor to improve the quantum dots’ luminous efficiency through the surface plasma effect of the Au nano-particles. And then this kind of quantum dots systems were applicated to white LED. We will research the preparation, coupling and optical characteristics of the Au nano-particles and core/shell CdSe/ZnS, and the mechanism of the increasing of the light emission of the quantum dots by the Au nano-particle’s surface plasma effect. According to the different thermal decay and luminous efficiencies of the quantum dots and the phosphor, we will research the stratiform hybrid of the quantum dots and phosphor, remote chip design, ratio of the hybrid light and photon recycling absorbtion, and so on. After carrying out of this project, we will obtain: (1)the optimization means of the preparation of the Au nano-particle and the CdSe/ZnS quantum dots/phosphor coupling system; (2)the optimization packaging style of the quantum dots and YAG phosphor; (3)the interaction among the excitation light, fluorescence of the Au nanoparticle-CdSe/ZnS quantum dots coupling system and the local electromagnetic fields; (4) the fluorescence enhancement mechanism of the Au nanoparticle to CdSe/ZnS quantum dots; And finally the high luminous efficiency, high color rendering index and high thermal stability white LED will be obtained. This project about quantum dot/phosphor coupling system and its fluorescence enhancement mechanism research has important scientific significance, and combining with the special packaging design to improve the LED luminous efficacy and light color stability has important practical significance and application prospect.

针对光转换型白光LED显色指数差及量子点补色带来的LED光效偏低问题，提出采用Au纳米粒子量子点/荧光粉耦合体系来实现高光效高显色性白光LED。通过研究Au纳米粒子和核壳CdSe/ZnS量子点的制备、耦合、光学特性及表面等离子共振荧光增强，获得Au纳米粒子量子点耦合体系荧光及显色指数调控机理；针对YAG荧光粉与量子点耦合体系的光效及温度淬灭不同，进行量子点/荧光粉分层及远离芯片封装设计等研究，获得Au纳米粒子量子点/荧光粉耦合体系的最佳制备和耦合方法及封装模式；探寻激发光、量子点耦合体系的荧光与局域电磁场之间的相互作用关系；阐明量子点耦合体系表面等离子共振荧光增强机理；最终获得高显色、高光效和光色稳定的白光LED。本项目关于Au纳米粒子量子点/荧光粉耦合体系及其荧光增强调控机理研究具有重要科学意义，而结合特殊封装设计来提高LED的光效和光色稳定性又具有重要的现实意义和应用前景。

本项目针对光转换型白光LED显色指数差及量子点补色带来的LED光效偏低问题，提出采用纳米粒子量子点/荧光粉耦合体系来实现高光效高显色性白光LED。通过研究核壳CdSe/ZnS量子点的制备、耦合、光学特性及表面等离子共振荧光增强，获得纳米粒子量子点耦合体系荧光及显色指数调控机理；针对YAG荧光粉与量子点耦合体系的光效及温度淬灭不同，进行量子点/荧光粉分层及远离芯片封装设计等研究，获得量子点/荧光粉耦合体系的最佳制备和耦合方法及封装模式；探寻激发光、量子点耦合体系的荧光与局域电磁场之间的相互作用关系；阐明量子点耦合体系表面等离子共振荧光增强机理；将获得的荧光材料进行封装，实现白光LED光效大于120 lm/W和显色指数大于90，量子点的量子效率>50%。项目发表学术论文21篇，其中SCI收录16篇，授权发明授权6项，培养研究生6名。得到以下重要成果：. 实验制备CdSe/CdS，CdSe/ZnS/CdS等尺寸为10纳米以下的核/壳结构或者核/壳/壳结构量子点；荧光发射峰的半高宽小于30nm，荧光量子产率为40-60％；研制了核-壳结构的CdSe/ZnSe、CdS/ZnS等尺寸为10纳米以下的量子点，研究其被蓝光芯片激发时的激发光谱，光致发光效率，发热，寿命等，得出了用于蓝光激发的单芯白光LED的最佳量子点材料、尺寸和发射光谱；以硫代乙酸同时作为碳源和硫源，220°C水热条件下保温10小时，制备得到硫掺杂碳量子点。CDs-S具备优异的荧光性能，在紫外灯下呈现蓝色荧光，其颗粒分散均匀，结晶性良好； 利用水热法首次合成了F/N共掺碳量子点，其荧光量子产率可以达到50%。F/N共掺碳点粒径分布在2.3 nm到5.4 nm左右，使得其半高宽可达到100 nm。含F/N基团的引入，使得碳点荧光强度极大限度的增强，是相同条件下制备的无掺杂碳点的18倍。经透析和干燥过后可得分散均匀的粉末，利用粉末态F/N共掺碳点与灌封胶混合得到F/N共掺碳点薄膜，与410 nm蓝光LED芯片结合制造成白光LED器件；使用高质量的具有核壳结构的CdSe，CdSe/CdS和CdSe/CdS/ZnS量子点作为发光层，进行YAG纳米荧光粉和量子点ZnSe/ZnS或CdSe/ZnS/ZnSe的掺杂和封装测试，实现白光LED光效显色指数大于90，量子点的量子效率>50%。