摘 要

量子点荧光太阳能聚光器由于利用无机量子点替代有机荧光分子，使其具有以下优点：（i）可以通过选择量子点直径来调整吸收阈值；（ii）它们可以提供高发光量子效率；（iii）它们比染料更稳定。近年来量子点荧光太阳能聚光器已成为太阳能电池领域研究的热点。透明介质中的量子点，尤其是溶胶-凝胶二氧化硅玻璃中的量子点，由于在荧光太阳能聚光器的应用前景广阔受到广泛关注。

本文采用溶胶-凝胶法制备掺CdS量子点的SiO₂复合薄膜，并通过调节Si/Cd比和热处理温度来观察二者对掺CdS量子点的SiO₂复合薄膜的微观形貌和光学性能的影响，使用XRD、SEM等技术手段对其性能进行表征。主要的研究内容和实验结果如下：

1）在控制Cd/Si比的实验当中，XRD测试结果显示掺CdS量子点的SiO₂复合薄膜在26.5°，43.9°，51.9°等处出现了CdS量子点的对应晶面特征峰，并且掺杂的CdS量子点越多，它的XRD特征峰更加尖锐，峰强也更高。从扫描电镜和透射电镜中可以看到掺CdS量子点的二氧化硅颗粒的球形颗粒与壳层结构，并且随着Cd/Si比的增加，壳层变厚。在荧光光谱和吸收光谱的分析中，可以得出掺杂CdS量子点可以使得二氧化硅薄膜的光吸收峰向可见光区移动，同时提高薄膜的荧光强度，Cd/Si比为0.5%时荧光强度最高，约为未掺杂时的5倍。当CdS量子点浓度过高则会导致浓度猝灭效应，导致荧光强度下降。

2）在控制热处理温度的实验中，实验发现随着温度提高，CdS量子点的尺寸变大，吸收光谱红移。在扫描电镜和透射电镜的分析中，看到了CdS-SiO₂的球形颗粒与核壳结构，球形颗粒直径约为0.4微米，壳厚约20纳米。并且随着热处理温度提高，核壳结构也在不断变厚。温度过高时，斯托克斯位移值变小，量子点的发光效率下降，应此选择较低温度373K为最佳的实验条件。

3）获得了掺杂CdS量子点溶胶-凝胶SiO₂玻璃最佳实验条件，即：Cd/Si比为0.5%，热处理温度为373K。在该条件下制备的掺量子点的二氧化硅薄膜荧光强度最高。这一实验结果为制备量子点荧光太阳能会聚器提供了有力的参考。

关键词：量子点；二氧化硅薄膜；溶胶-凝胶法；光致发光；太阳能荧光会聚器

Abstract

Quantum dot fluorescent solar concentrator, which uses inorganic quantum dots to replace organic fluorescent molecules, has the following advantages :(I) the absorption threshold can be adjusted by selecting the diameter of quantum dots;(ii) they can provide high luminous quantum efficiency;(iii) they are more stable than dyes.In recent years, quantum dot fluorescent solar concentrator has become a research hotspot in the field of solar cells. Quantum dots in transparent media, especially in sol-gel silica glass, have attracted much attention due to their wide application prospects in fluorescent solar concentrators.

In this paper, the SiO₂ composite film doped with CdS quantum dots was prepared by sol-gel method, and the influences of the Si/Cd ratio and the heat treatment temperature on the microstructure and optical properties of the SiO₂ composite film doped with CdS quantum dots were observed by adjusting the Si/Cd ratio and the heat treatment temperature. The properties of the SiO₂ composite film doped with CdS quantum dots were characterized by XRD, SEM and other technical means.The main research contents and experimental results are as follows:

1) in the control of Cd/Si ratio experiment, XRD test results show that the mixed CdS quantum dots of SiO2 composite film in 26.5 °, 43.9 ° and 51.9 ° and the corresponding crystal face CdS quantum dots characteristic peak, and doping CdS quantum dots, the more its XRD characteristic peak more sharp, strength is higher can be seen in the scanning electron microscopy (SEM) and transmission electron microscopy (SEM) with CdS quantum dots of spherical particles of silica particles and the shell structure, and with the increase of Cd/Si ratio, shell thickness. In the analysis of fluorescence spectrum and absorption spectrum, it can be concluded that doping CdS quantum dots can make the light absorption peak of the silica film move to the visible light region, and meanwhile increase the fluorescence intensity of the film. When the Cd/Si ratio is 0.5%, the fluorescence intensity is the highest, about 5 times that of the undoped one. When the concentration of CdS quantum dots is too high, the concentration quenching effect will be caused and the fluorescence intensity will decrease.

2) in the experiment of controlling the heat treatment temperature, it was found that as the temperature increased, the size of CdS quantum dots increased and the absorption spectrum redshifted. In the analysis of scanning electron microscope and transmission electron microscope, the spherical particles and core-shell structure of Cds-SiO2 were observed. The diameter of the spherical particles was about 0.4 micron, and the shell thickness was about 20 nanometers. And as the heat treatment temperature increases, the core-shell structure also thickens. When the temperature is too high, the stokes displacement becomes smaller and the luminous efficiency of quantum dots decreases. Therefore, a lower temperature of 373K should be selected as the best experimental condition.

3) the optimal experimental conditions of the sol-gel SiO₂ glass doped CdS quantum dots were obtained, that is, the Cd/Si ratio was 0.5%, and the heat treatment temperature was 373K.The fluorescence intensity of silicon dioxide films doped with quantum dots was the highest under the experimental conditions. This experiment provides a powerful reference for the application of silicon dioxide films doped with quantum dots and the preparation of solar fluorescent converters with excellent performance.

Key words: Quantum dots; Silicon dioxide film; Sol-gel method; Photoluminescence ; Solar fluorescent converters

目 录

摘 要 I

Abstract III

第1章 绪论 1

1.1引言 1

1.2量子点概述 1

1.2.1 量子点的基本效应 1

1.2.2量子点种类及其特性 2

1.2.3 量子点在光电领域的应用 3

1.2.4 量子点的制备方法 3

1.3荧光型太阳能聚光器 4

1.3.1荧光太阳能聚光器主要构与工作原理 4

1.3.2荧光型太阳能会聚器的性能参数 6

1.3.3荧光型太阳能聚光器的发展现状 8

1.4 二氧化硅薄膜的制备方法 8

1.5本论文的研究内容与研究意义 9

第2章 实验部分 11

2.1实验药品与仪器 11

2.1.1实验药品 11

2.1.2实验仪器 11

2.2实验过程 12

2.2.1 SiO₂前驱体（溶胶）的配置 12

2.2.2 CdS量子点的制备 12

2.2.3溶胶-凝胶法制备含CdS量子点的氧化硅薄膜 13

第3章 实验的结果与讨论 14

3.1Cd/Si比对掺CdS量子点的二氧化硅薄膜性能的影响 14

3.1.1 X射线衍射分析（XRD） 14

3.1.2 扫描式电子显微镜观察（SEM） 15

3.1.3透射电子显微镜观察（TEM） 16

3.1.4 光致发光性能检测（PL） 17

3.1.5 紫外-可见吸收光谱检测（UV-vis） 18