铜铟硫基半导体量子点光电特性及其应用的研究

发布时间：2019-03-08 08:14

【摘要】：在半导体量子点中，因为有量子限域效应的存在，使得其具有独特的光学性质。因此，其在生物、光电及光伏等领域具有重要的应用前景。本文基于绿色化学的理念，从材料的合成、光学机理及应用等方面，对无毒的铜铟硫基量子点展开实验研究，取得了以下创新研究成果： 1．量子点光学机理方面的研究。我们合成了CuInS2量子点、CuInS2/ZnS核/壳量子点以及ZnCuInS/ZnSe/ZnS核/壳/壳量子点。在对其性能的表征过程中，发现了此类量子点具有的一些特性，包括吸收光谱和发光光谱均较宽，存在着较大的Stokes位移等，这是由其能带结构及发光机理决定的。较大的Stokes位移（400-500meV）证明，在此类量子点中主要的复合过程是与缺陷能级有关的复合。而较为明显的尺寸依赖效应同时证明了，施主-受主对（donor-acceptorpair，缩写DAP）复合是该类量子点的多种主要的复合过程之一，而并不是占主导的复合过程。分别测试了ZnCuInS/ZnSe/ZnS核/壳/壳量子点、Cu与In比例不同的CuInS2量子点及CuInS2/ZnS核/壳量子点的温度依赖的光致发光光谱和时间分辨光致发光光谱。通过对多种光谱的分析，我们深入地研究了此类量子点的复合机理。并提出了，在此类量子点中，同时存在着多种复合过程，包括与表面态有关的复合、导带与缺陷能级间的复合以及DAP复合。然后，我们改变CuInS2量子点及CuInS2/ZnS核/壳量子点中Cu与In的比例，分析其温度依赖的光致发光光谱发现，当In组分含量增大时，在与表面态有关的复合、导带与缺陷能级间的复合以及DAP复合中，，DAP复合所占的比重有所增加。 3．基于ZnCuInS/ZnSe/ZnS核/壳/壳量子点发光的温度特性的研究，我们将其应用于微区、面阵的温度传感中。测得该量子点光致发光强度随温度变化的系数（温度系数）达到0.66%/oC。使用光纤光谱仪与高倍显微镜组成了测试系统，通过测试微米区域的量子点的光致发光光谱来完成微区、面阵的温度检测。该系统测试的误差低于2%。 4．量子点发光二极管（QD-LED）的制备及温度效应的研究。将三个尺寸的ZnCuInS/ZnSe/ZnS核/壳/壳量子点分别与GaN发光二极管组装，制成了红光、黄光和绿光的QD-LED。在2.6V的工作电压下，相应的三种颜色的QD-LED的功率效率依次为14.0lm/W、47.1lm/W和62.4lm/W。通过对不同工作电压下QD-LED的色坐标，光谱峰位，半峰宽及功率效率的分析，我们研究了QD-LED的温度效应。结果表明，就器件的功率效率随着电压升高的下降而言，发光二极管表面温度的升高引起的热猝灭是一个不可忽视的因素。同时ZnCuInS/ZnSe/ZnS核/壳/壳量子点的发射峰位的温度系数很低（红光，黄光及绿光量子点的温度系数分别为0.022nm/oC、0.050nm/oC和0.068nm/oC），这使得QD-LED的色坐标在不同工作电压下，变化非常小，证明了该QD-LED的颜色稳定性好。与CdSe量子点的相应数据相比，ZnCuInS/ZnSe/ZnS核/壳/壳量子点在颜色稳定性方面，更适合做下转换材料。
[Abstract]:In semiconductor quantum dots, due to the existence of quantum confinement effect, it has unique optical properties. Therefore, it has an important application prospect in biological, photoelectric and photovoltaic fields. In this paper, based on the concept of green chemistry, the nontoxic copper-indium-sulfur-based quantum dots have been experimentally studied from the aspects of material synthesis, optical mechanism and application, and the following innovative achievements have been obtained: 1. The optical mechanism of quantum dots has been studied. We have synthesized CuInS2 quantum dots, CuInS2/ZnS core / shell quantum dots and ZnCuInS/ZnSe/ZnS core / shell quantum dots. During the characterization of the quantum dots, some properties of these quantum dots were found, including the wide absorption and luminescence spectra, and the existence of a large Stokes shift, which is determined by the energy band structure and the luminescence mechanism. The large Stokes shift (400-500meV) proves that the main recombination process in this kind of quantum dots is the recombination related to the defect energy level. The obvious size-dependent effect also proves that the donor-acceptor pair (donor-acceptorpair,-acceptor pair) recombination is one of the main recombination processes of this kind of quantum dots, but not the dominant one. The temperature-dependent photoluminescence spectra and time-resolved photoluminescence spectra of ZnCuInS/ZnSe/ZnS core / shell quantum dots, CuInS2 quantum dots with different ratio of Cu to In and CuInS2/ZnS core / shell quantum dots were measured. Through the analysis of many kinds of spectra, we have studied the recombination mechanism of this kind of quantum dots in depth. It is also proposed that there are many kinds of recombination processes in the quantum dots, including the recombination related to the surface states, the recombination between the conduction band and the defect level, and the DAP recombination. Then, we change the ratio of Cu to In in CuInS2 QDs and CuInS2/ZnS core / shell QDs and analyze their temperature dependent photoluminescence spectra. The recombination between conduction band and defect level and the proportion of DAP recombination in DAP recombination increased. 3. Based on the study of temperature characteristics of ZnCuInS/ZnSe/ZnS core / shell quantum dots, we apply them to temperature sensing of micro-region and area array. The coefficient (temperature coefficient) of photoluminescence intensity of the quantum dot with temperature is 0.66%, and the temperature coefficient of photoluminescence of the quantum dot is 0.66%. An optical fiber spectrometer and a high power microscope are used to measure the temperature of the micro-region and the area array by measuring the photoluminescence spectra of the quantum dots in the micron region. The test error of the system is less than 2%. 4. Preparation of quantum dot light emitting diode (QD-LED) and study of temperature effect. Three sizes of ZnCuInS/ZnSe/ZnS core / shell quantum dots were assembled with GaN light emitting diodes to produce QD-LED. with red, yellow and green light. Under the operating voltage of 2.6 V, the power efficiency of the corresponding three colors of QD-LED is 14.0 lm / W, 47.1lm / W and 62.4lm / w, respectively. By analyzing the color coordinates, spectral peak position, half-peak width and power efficiency of QD-LED at different operating voltages, we have studied the temperature effect of QD-LED. The results show that the thermal quenching caused by the rising surface temperature of light emitting diodes is an important factor for the decrease of the power efficiency of the devices with the increase of the voltage. At the same time, the temperature coefficients of the emission peaks of ZnCuInS/ZnSe/ZnS core / shell QDs are very low (the temperature coefficients of red, yellow and green QDs are 0.022 nm C, 0.050 nm C and 0.068nm/oC, respectively). This makes the color coordinates of QD-LED change little under different working voltages, which proves that the color stability of the QD-LED is good. Compared with the corresponding data of CdSe QDs, ZnCuInS/ZnSe/ZnS core / shell QDs are more suitable for down-conversion materials in terms of color stability.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O471.1

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