高显色性量子点白光LED发光材料及器件研究

白光LED具有低阈值电压、高亮度及低能耗等优点。但目前为止，白光LED主流产品是用蓝光LED激发黄色荧光粉获得白光输出，因为欠缺红光波段，显色指数偏低，多在60-80之间，如果能将显色指数提高至90或以上，LED的照明应用领域将会更为宽广。本项目提出采用三基色量子点材料代替传统荧光粉作为白光LED器件的光泵荧光材料，利用单一蓝光LED光源激发不同大小的量子点，可以产生各种色光，从红、橙…到蓝，类似彩虹光谱，不仅有望提升白光LED的显色性，还有望延长目前白光LED器件的寿命。我们采用低毒Zn类核壳量子点掺杂的方法来解决斯托克斯位移小的问题，从而提高发光效率和温度稳定性，同时深入研究掺杂和颗粒尺寸对量子点发光机制的影响，建立掺杂量子点能级结构模型，通过三基色量子点的复合及量子点粒径的调控，结合半导体量子点的配色特性，实现高显色性白光输出，为研制新型绿色环保高性能固态照明器件打下技术基础。

As the fourth generation light source, white LED (WLED), the novel solid cold light source, has the advantages of low threshold voltage, high brightness, low energy consumption and quick response. But so far, whether it is made from the blue LED and yellow fluorescent powder, polycrystalline RGB or other process, the average color rendering index (CRI) value of existing white LEDs is low, which is about 60-80. If the CRI value of WLED can be raised to 90 or more, the application fields of WLED will be wider. In this project we proposed to use trichromatic quantum dots (QDs) instead of fluorescent powder as luminescent material of white LED devices for fabricating corresponding QD-WLED, which can be expected to not only enhance the CRI of WLED, making your eyes feel comfortable just like in the sun light or incandescent light, but also extend the lifetime of WLED devices, overcoming the short service lifetime of the fluorescent powder. The low toxic zinc group core-shell QDs are doped with transition metal ions for enlarging the Stokes shift and improving the luminescence efficiency and temperature stability. The luminescent mechanism of the doped QDs is systematically investigated and the corresponding energy level structure model is established. White light with high CRI can be realized via mixing of red, green, and blue luminescent QDs and their size control, which can lay the foundation for technological development of new green high performance solid state lighting devices.