高效环保型 InP 量子点研究

RESEARCH ON EFFICIENT AND ENVIRONMENTAL FRIENDLY INP QUANTUM DOTS

陈璘珣

11849145

硕士

材料工程领域工程

孙小卫

2020-05-28

2020-07-20

哈尔滨工业大学

深圳

量子点(QDs)是一种新型的半导体材料，由于带隙可调和良好的光致发光性能备受瞩目，被广泛应用于生物医学、细胞成像等领域。近年来，镉基量子点，由于光学性能优异而广受显示、照明领域的欢迎。但镉元素的生物毒性限制了镉基量子点在免疫分析、生物医学等领域的应用，对环境和人体都有巨大危害。本文研究的对象是无镉量子点磷化铟（InP），探究了发光原理，合成方法与器件应用等内容。当前InP量子点还存在量子产率较低，无法大规模生产等问题，严重制约了InP QDs的应用。 本研究采用核壳结构解决InP量子点量子产率不高的问题，对InP分别包覆不同的壳层(ZnSe和ZnS)和不同厚度的壳层，通过对比分析发现硒化锌（ZnSe）在一定程度上可以兼顾带隙和晶格常数（ZnSe 5.66 Å）的问题，但由于ZnSe的势垒较小，核心内的电子和空穴不易被限制，容易跃迁至壳层，导致光谱红移，而为了得到绿光，需要将核心尺寸减小，使之色彩更纯。当体积较小时，比表面积相对较大，因此表面缺陷增多，量子产率大大降低，并且其自身的化学稳定性也制约ZnSe的应用。通过摸索最佳反应温度、时间、投料比，最后我们发现硫化锌（ZnS）为最佳的包覆层，更好的限制了电子空穴的跃迁，并且得到的InP量子点具有更好的稳定性和更高的量子产率，产率可达75.1%，量子点发光二极管(QLED)器件最大的外量子效率可达2.7%。我们又探索了InP/ZnSe/ZnS，InP/ZnS/ZnS双壳层结构，通过增加壳层的厚度可以增加量子点的稳定性。

Quantum dots(QDS) are widely used in bioluminescence, cell imaging and other fields due to their well-coordinated and excellent photoluminescence properties. In recent years, cadmium-based quantum dots, led by CdSe, have been widely adopted. However, the biological toxicity of cadmium compound limits the application of cadmium-based quantum dots in immune analysis, biomedicine and other fields, causing great harm to the environment and human body. The research object of this project is cadmium-free quantum dot indium phosphor(InP), and the luminescence principle, synthesis method and device application are also explored. However, at present, the quantum yield of InP QD is still relatively low, and large-scale production cannot be achieved, which seriously restricts the application of InP QDs.In this paper, the study of core-shell structure is conducted to solve the problem of low quantum yield of InP quantum dots. The InP core is coated with different shells and different shell thickness：InP/ZnSe, InP/ZnSe/ZnS, InP/ZnS, InP/ZnS/ZnS four shell structured quantum dots, by contrasting, analysis and find that zinc selenide(ZnSe) to some extent can solve the problem of band gap and the lattice constant(5.66 A), but because ZnSe potential barrier is small, the electrons and holes within the core is not easy to be restricted, and is very easy to jump into the shell, causing spectrum redshift. In order to get the green light, the shell thickness of ZnSe needs to be increased to limit the transition of holes and electrons, which can make colour more pure. The smaller the volume gets, the larger the specific surface area is. As a result, the surface defects increases, the quantum yield reduces, also its chemical stability limits the application of ZnSe. Whereafter, we explored the InP/ZnSe/ZnS, InP/ZnS/ZnS double shell structure, find that DDT ligand is replaced by the TOP when covering the second ZnS layer, causing the formation of defect mode. Therefore, the QY decreases. By exploring the optimal reaction temperature, time and materials ratio, we finally find that zinc sulfide (ZnS) is the optimal cladding layer, which better limits the transition of electrons and holes, and the obtained InP quantum dots have better stability and higher quantum yield. The maximum quantum yield and external quantum efficiency obtained was 75.1% and 2.7% respectively. We also explore the InP/ZnSe/ZnS, InP/ZnS/ZnS double shell structures, the stability of the quantum dots can be increased by increasing the thickness of the shell.

核壳结构 磷化铟 硫化锌 硒化锌

core-shell structure InP ZnS ZnSe

中文

联合培养

南方科技大学

陈璘珣. 高效环保型 InP 量子点研究[D]. 深圳. 哈尔滨工业大学,2020.