半导体纳米晶体CdTe和CdS的微波水相合成、掺杂及荧光性质的研究

发布时间：2018-07-29 09:31

【摘要】：半导体纳米材料由于其比较明显的量子尺寸效应、电子限域效应以及良好的抗光漂白性等优良性能，同时其发光性质可以通过改变尺寸或对其掺杂离子进行精细调节，而被大量运用在制造量子点激光器、太阳能电池、发光二级管、生物DNA标记及探针等领域。半导体纳米材料掺杂金属离子后，不仅可以维持原有的优良性能，同时能够避免斯托克斯现象，并可以进一步对量子点的光学、电学等性质进行调节，因此也受到了广泛的研究开发。传统制备的纳米晶体虽具有尺寸可控且发光性能优良等优点，但多采用有机金属合成方法，所用试剂价格不仅昂贵，而且使用的表面活性剂多数毒性较大，不利于绿色化学的发展，更不适用于大规模生产。本文采用微波水相合成方法合成了半导体纳米晶体CdTe和CdS，并对其进行了掺杂和荧光性质的研究。主要取得了以下研究成果：（1）采用微波水相法，在较短时间内合成了高质量且尺寸均匀、粒径较小的球状碲化镉（CdTe）半导体纳米晶体。通过粉末X-射线衍射（XRD）测试，，确定了所得样品均为结晶度较好的具有立方闪锌矿结构的目标纳米晶体。通过高分辨透射电镜（TEM）测试可以确定所得样品为粒径5-6nm的球形颗粒。在改变反应温度以及时间的情况下，我们对所合成的CdTe纳米晶体光学性质进行了研究：在反应时间一定时，CdTe纳米晶体的紫外吸收峰以及荧光发射峰随着温度升高而发生红移，荧光强度基本按照抛物线形式先升高后降低；在反应温度一定时，随着时间的增加，荧光发射峰红移，且荧光强度先升高后降低，这些特征都与纳米晶体的生长规律以及小尺寸效应相关。（2）采用微波水相法，以巯基丙酸（MPA）为稳定剂，利用中心掺杂技术在不同时间内快速合成了高质量的掺杂半导体纳米晶体CdS:Cu。铜离子均匀分布在纳米晶体的中心内部，而且可以通过CuS核和CdS层的界面扩散进行阳离子交换过程。通过XRD测试发现所得样品为立方闪锌矿结构，通过TEM测试发现所合成的掺杂纳米晶体具有良好的晶体结构。尤其是利用中心掺杂技术掺入的Cu2+离子有效改进了CdS在光学性质、量子产率以及光化学稳定性方面的性能。通过掺杂Cu2+离子使CdS纳米晶荧光发射峰从538nm调节到630nm，即呈现红色荧光。相比于传统的合成方法，本文所采用中心掺杂方法合成的产物荧光性质优良，并且具有良好的光化学稳定性，可以长期稳定的存储。
[Abstract]:Semiconductor nanomaterials have excellent properties such as obvious quantum size effect, electron limiting effect and good photobleaching resistance, and their luminescence properties can be adjusted by changing their size or doping ions. It has been widely used in the fields of quantum dot lasers, solar cells, light-emitting secondary tubes, biological DNA labeling and probes. After doping metal ions, semiconductor nanomaterials can not only maintain the original excellent performance, but also avoid Stokes phenomenon, and further adjust the optical and electrical properties of quantum dots. Therefore, it has also been extensively researched and developed. Although the traditional nanocrystals have the advantages of controllable size and excellent luminescence properties, they are usually synthesized by organometallic methods. The price of the reagents used is not only expensive, but also most of the surfactants used are more toxic. Not conducive to the development of green chemistry, not suitable for mass production. In this paper, semiconductor nanocrystals CdTe and CDs were synthesized by microwave aqueous phase synthesis, and their doping and fluorescence properties were studied. The main results are as follows: (1) the spherical cadmium telluride (CdTe) semiconductor nanocrystals with high quality uniform size and small particle size were synthesized by microwave aqueous phase method in a short time. The results of X-ray diffraction (XRD) show that the samples are all target nanocrystalline with cubic sphalerite structure with good crystallinity. High resolution transmission electron microscopy (TEM) measurements showed that the samples were spherical particles with 5-6nm diameter. The optical properties of the synthesized CdTe nanocrystals were studied by changing the reaction temperature and time. The UV absorption and fluorescence emission peaks of the CdTe nanocrystals were red-shifted with the increase of the temperature when the reaction time was fixed. The fluorescence intensity increased at first and then decreased in the form of parabola, and when the reaction temperature was fixed, the fluorescence emission peak shifted red with the increase of time, and the fluorescence intensity increased first and then decreased. These characteristics are related to the growth law of nanocrystalline and the small size effect. (2) the microwave aqueous phase method and mercaptopropionic acid (MPA) as stabilizer, The high quality doped semiconductor nanocrystalline CDs _ (1) Cu _ (2) was synthesized by the center doping technique in different time. Copper ions are uniformly distributed in the center of the nanocrystalline and can be exchanged through the interface between the CuS nucleus and the CdS layer. The samples were found to have cubic sphalerite structure by XRD test, and the doped nanocrystals were found to have good crystal structure by TEM test. In particular, the Cu2 ion doped by the center doping technique can effectively improve the optical properties, quantum yield and photochemical stability of CdS. The fluorescence emission peak of CdS nanocrystalline was adjusted from 538nm to 630 nm by doping Cu2 ion, that is, red fluorescence. Compared with the traditional synthesis methods, the products synthesized by the central doping method have excellent fluorescence properties and good photochemical stability, and can be stored steadily for a long time.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O614.242

【参考文献】