磷化铟基核壳量子点结构设计和发光特性研究

Indium phosphide (InP) core/shell quantum dot based quantum dot light emitting diodes (QLED) are considered as promising light sources for the next generation solid-state lighting and displays, due to not only their advantages of traditional QLED but also the heavy metal-free (Cd, Pb etc.) feature. The low luminescence efficiency and brightness of InP based QLEDs are the major obstacles limiting their practical applications. Therefore, the improvement of matching in energy levels to increase the carrier injection efficiency and the controlling of the QD fluorescence blinking are the key scientific issues needed to be resolved. Focusing on these issues, this project will present a systematic study on the electronic and excitonic properties of InP quantum dots, core/shell and core/multishell quantum dots by combining large scale ab initio method, million-atoms plane wave empirical pseudopotential method and configuration interaction approach. The emphasis will be put on the impacts of the nature of shell material, shell thickness and its composition on the electronic structure, and on the optical properties of neutral and charged exciton. On ground of these results, an optimal shell will be designed so that the energy levels of QD emitting layers match their counterparts of the other functional layers. On the other hand, the physical picture behind QD blinking will be significantly enriched based on the study of optical properties of different type of excitons. This project will be very useful for the research and development of InP based QLED with high efficiency and brightness.

基于磷化铟（InP）核壳量子点构筑的量子点发光二极管（QLED）不仅具有传统QLED的优点，更因其不含镉、铅、汞等有毒重金属元素而有望在下一代固态发光和平板显示中得到广泛应用。发光效率和亮度显著偏低是限制InP基QLED走向实际应用的主要障碍。因此如何提高核壳量子点发光层与其它功能层之间的能级匹配度以提高载流子的注入效率，同时抑制量子点荧光闪烁是目前急需解决的关键性科学问题。本项目采用大尺度第一性原理方法、百万原子平面波经验赝势方法和组态相互作用方法研究单核、核壳和核多壳InP量子点的电子结构和激子发光特性。重点研究壳层种类、厚度和组分对量子点电子结构及中性和带电激子光学性质的调制作用。在此基础上，通过优化壳层设计，实现量子点发光层与其它功能层之间的能级匹配。通过不同种类的激子发光性能的研究，丰富量子点闪烁的物理图像。本项目对实现高效率、高亮度InP基QLED的研发工作有着重要意义。

基于环境友好型量子点构筑的量子点发光二极管不仅具有传统量子点发光二极管的优点，更因其不含镉、铅、汞等有毒重金属元素而有望在下一代固态发光和平板显示中得到广泛应用。发光效率和亮度显著偏低是限制其走向实际应用的主要障碍。本项目结合大尺度杂化密度泛函和含时密度泛函理论，系统研究了III-V族和II-VI族环境友好型量子点材料的电子结构和发光特性。探明了量子点光学特性随材料类型、尺寸、壳层厚度、表面配体等因素的调控规律。结合实验研究，实现了外量子效率6.3%的绿光、外量子效率1.01%的蓝光磷化铟发光器件以及外量子效率12.2%的硒化锌蓝光器件的构筑，探明了器件高效率背后的物理机制。在Nano Letters、Physical Review B、Journal of Physical Chemistry Letters等国际知名期刊上发表SCI论文10篇。培养硕博连读生1名，硕士研究生3名。本项目研究成果对高效高亮环境友好型量子点发光器件研发具有重要指导意义。