CuInS2量子点在远程白光LED中应用的关键表面和界面问题研究

In response to the demands for energy and the concerns of global warming and climate change, energy efficient and environmentally friendly solid-state lighting, such as white light-emitting diode (WLED), is considered to be the most promising and suitable light source. Effective lighting devices can be realized by combining one or more luminescent materials with blue emissive chips. Accordingly, it is very important to develop the materials and architecture of phosphors. Because of the small size, highly luminescent efficiency, and tunable emission spectra, colloidal quantum dots are emerging as novel luminescent materials to enhance the color performance of lighting and display technology. Colloidal CuInS2 based quanqutm dots exhibit tunable spectroscopic properties with particular properties such as wide tunable spectral window covering the visible to NIR region (500-750 nm), larger Stokes shifts (> 200 meV), broaden emission spectra with full width at half maximum (FWHM) of 90 to 120 nm, and a longer photoluminescence lifetime, as well as possible low toxicity and low cost. All of these features might provide ways to enhance the performance of WLEDs and create “smart” lighting systems. Recently, we have reported the fabrication of high color rendering (up to ~95) and high efficiency (up to ~70 lm/W) pc-WLEDs using CuInS2 based quantum dots. However, the LED devices using traditional encapsulation ways have heat dissipation problems, which lead to serious degradation of the phosphors. In this project, we proposed the investigatation of the photochemical degradation process of quantum dots in the nanocomposites and clarify the mechanism that underline the photoluminescence quenching effect during LED operation. To overcome the challenge, we also proposed to develop high quality nanocmposites with high transparency and high luminescence effiency through surface ligand and interface engineering. As such, the proposed work not only benefits fundamental material and chemistry science, but also provides compelling opportunities for the realization of improved WLEDs technologies.

白光LED是新一代绿色固态照明技术，发展与白光LED相关的新材料与新技术，具有十分重要的意义。CuInS2量子点具有波长可调、Stokes位移大、发光光谱宽、易量产和低毒、低成本等特点，是一类潜在的荧光转换材料，在白光LED中具有应用潜力。本项目拟在前期研究基础上，针对CuInS2量子点在远程白光LED中亟待解决的光、热和化学稳定性以及量子点与基质材料之间的相容性问题，开展表面调控研究，提升量子点的荧光量子效率；开展量子点在工作环境中的稳定性研究，揭示其荧光衰减机制；发展表面界面调控策略，解决高性能量子点复合过程中的分散性问题，构筑表面微纳光学结构，提高量子点复合材料的光转换效率，获得高性能远程白光LED器件。课题研究涉及到量子点应用中的关键“表面和界面”科学问题，研究的开展可推动量子点LED应用的发展，同时为“纳米颗粒”的应用提供理论基础和实验技术。

CuInS2量子点具有波长可调、Stokes位移大、发光光谱宽、易量产和低毒、低成本等特点，是一类重要的量子点材料，在白光LED荧光转换、医学成像、太阳能聚光等领域中具有应用潜力。本项目针对CuInS2量子点在远程白光LED中亟待解决的光、热和化学稳定性以及量子点与基质材料之间的相容性问题，开展表面调控研究，提升量子点的荧光量子效率；开展量子点在工作环境中的稳定性研究，揭示其荧光衰减机制；发展表面界面调控策略，解决高性能量子点复合过程中的分散性问题，构筑表面微纳光学结构，提高量子点复合材料的光转换效率，获得高性能远程白光LED器件。本项目发明了简单可靠的量子点原位配体交换技术，可制备出能够在醇、N,N二甲基甲酰胺、二甲亚砜等极性溶剂分散的铜铟硫量子点材料，为量子点的表面功能化提供了一类新材料，提升了LED、太阳能电池等应用性能。在此基础上，课题组开拓了钙钛矿量子点的原位制备技术，突破了量子点在聚合物中分散的难题，同时解决了其在液晶显示应用的稳定性问题，所实现的白光LED原型器件的效率达到80lm/W，色域110%。以上成果作为“胶体量子点的可控合成和高品质LED应用研究”的重要创新点，获得北京市科学技术奖励二等奖（项目负责人排名第二）。其项目执行过程中，共发表学术论文22篇，会议论文1篇，申请专利7项，项目参与人参加美国显示学会SID年会、日本IDW显示年会等学术会议8次，其中包括国际会议邀请报告4次。执行期间，培养博士生2名、硕士生4名，项目负责人2017年获得国家科学基金优秀青年基金支持，参与人博士后陈冰昆获得北京理工大学预聘教授职位，参与人毕业生张峰获得中国化学化工学会京博材料类优秀博士论文银奖。

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