量子点壳层控制多层结构量子点发光二极管的电致发光性质的研究

项目名称： 量子点壳层控制多层结构量子点发光二极管的电致发光性质的研究

项目编号： No.10874179

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 赵家龙

作者单位： 中国科学院长春光学精密机械与物理研究所

项目金额： 48万元

中文摘要： 研究壳层结构对发光二极管中量子点的发光效率和亮度的影响和优化量子点及其器件结构是获得高效量子点发光二极管的关键科学问题。在本项目中利用化学方法，设计合成了不同结构的高效发光CdSe和ZnS:Mn等核壳量子点，研究了核壳量子点表面壳层与量子点及其发光二极管的发光性质关系，获得了如下创新性研究结果：（1）研究了不同结构CdSe核壳量子点的变温光致发光光谱，发现了多壳层有效地减少量子点的表面陷阱提高其发光效率的机制；利用成核掺杂方法合成了发光效率超过40%的ZnS:Mn/ZnS核壳纳米晶，研究了发光效率与壳层结构的关系；（2）制备了发光效率为3%和最大亮度达到7000cd/m2的CdSe量子点发光二级管，研究了量子点壳层对器件发光性能的影响，发现包覆高势垒ZnS壳层的CdSe量子点比包覆低势垒CdS壳层的CdSe量子点具有更高的最大亮度。（3）利用时间分辨光谱，研究了从有机电荷传输材料到CdSe量子点的电荷转移和激子能量转移过程的控制，分析了它们与量子点的壳层结构的关系。上述结果表明通过改变量子点的壳层结构，优化量子点发光器件的结构，为进一步改善量子点发光二极管的效率和亮度提供了物理基础。

中文关键词： 量子点；量子点发光二极管；电致发光；电荷转移；能量传递

英文摘要： Studying the effects of shell structures on the quantum efficiency and brigtness of quantum dot light-emitting diodes (QD-LEDs) and optimizing the structures of the QDs and their LEDs is an important factor to improve the performance of QD-LEDs. In this work we synthesized highly efficient photoluminescent CdSe and ZnS:Mn core/shell QDs with different shell structures, studied the effects of the shell structures on the photo- and electro-luminescence of QDs, and obtained some novel experimental results as follows: 1) The enhancement mechanism of the photoluminescence in CdSe QDs by coating a shell and multishell to passivate the traps on the surface of the QDs was explained based on temperature-dependent photoluminescence spectra. The ZnS:Mn/ZnS QDs with a photoluminescence efficiency of over 40% were synthesized. The effect of the shell thickness on the photoluminescence was studied. 2) The CdSe QD-LEDs with a quantum efficiency of over 2% and maximum luminance of 7000 cd/m2 were fabricated. The effect of the shell structures on the performance of the devices was studied in detail. It is found that the QDs with a high barrier ZnS shell exhibit higher maximum luminance that those with a low barrier CdS shell. 3) The control of the charge/energy transfer processes between the CdSe QDs and charge transport materials were studied to explore the effect of the shell on them. The experimental results indicate that the performance of the present devices with low quantum efficiency and brightness will be improved by changing and optimizing the structures of QDs and their devices.

英文关键词： Quantum dots; quantum dot light-emitting diodes; electroluminescence; charge transfer; energy transfer