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半导体量子点的研究:幻数尺寸、多模发射以及不同结构的量子点

发布时间:2018-12-29 12:47  文章来源:笔耕文化传播
【摘要】:胶体量子点之所以能吸引如此多的注意力是因为它们在生物标记、光伏、照明、激光、光催化、热电及新一代微电子器件中的潜在应用价值,这是过去几十年对其优化合成及光电性质深入研究的结果。在所有半导体量子点材料中,CdSe作为其中的典型材料拥有胶体量子点研究中的诸多第一,包括第一种利用胶体化学合成的总体尺寸分布小于10%的量子点,第一种连接生物分子并用于生物标记的胶体量子点,第一种将吸收和发光实验数据与理论计算的能带结构数据进行系统对比的材料等。三元合金半导体量子点的组分和结构都比二元的Ⅱ-Ⅵ族半导体量子点复杂,但是它们的光电性质可以通过改变半导体组分来调节,因此有可能提高吸收的同时改善其载流子输运性能,以促进在特定实践中的应用。因此,在本论文中主要以CdSe基核壳结构量子点及合金量子点为研究对象,采用非注入法可控制备了系列高效发光量子点;利用高温注射法制备了多种合金及其核壳结构量子点;研究了不同体系幻数尺寸量子点的合成;构筑了多模发光量子点材料;探讨了量子点的生长机制以及发光机理;研究了量子点的相转移方法,对量子点荧光探针的应用做了初步探索。具体研究内容如下:在第一章中,首先简单介绍了量子点的性质、结构与发光机理,然后进一步总结了人们近年来在半导体量子点合成与应用方面的研究进展以及存在的问题,提出了本论文的选题意义和主要研究内容。在第二章中,通过一种非注入方法,以ODE为溶剂,Se粉和Cd(SA)2为原料,合成了CdSe量子点。在合适的条件下可以观察到幻数尺寸(magic-sized)的量子点的形成,而且这些量子点在相对低温下展现出不寻常的连续生长模型。通过吸收光谱和发光光谱对CdSe量子点的生长动力学进行了研究,结果显示Se粉的溶剂是纳米晶成核的发生点和成核速率的限制因素。对比实验证实,与传统的高温热分解法合成相比,在非注入合成中量子点的生长呈现出迥异的动力学特征。用此非注入方法合成的量子点具有很高的结晶度,其荧光量子产率由原来的34%,利用ZnS钝化包覆后提高到63%,若在CdSe核与ZnS钝化层之间加入一层ZnSe过渡层,则具有核壳结构的CdSe/ZnSe/ZnS量子点的荧光量子产率荧光量子产率可高达74%,这与许多高温热分解法制备的量子点的发光水平相当。然后,我们进一步通过原位注入合成及后续包覆制备了多模发光CdSe/CdS/ZnS核壳结构量子点,并对其发光性质进行了系统研究。在第三章中,主要研究了利用高温注射法制备宽发射光谱覆盖的、不同形貌的CdTeSe基核壳结构量子点,系统研究了注入过程与反应温度的影响,并对生长机制做了合理探讨。通过对比球形CdTeSe量子点及其不同核壳结构量子点的3-D PL光谱,研究了不同钝化方式的量子点发光对激发波长依赖性的影响。与CdSe/ZnSe/ZnS量子点中的ZnSe壳层结构作用类似,CdTeSe/ZnSe/ZnS中的ZnSe层也扮演了重要角色:提供平滑的界面以及缓变的能带结构。最后,红光发射的核壳结构量子点被转移到水相,并成功用于对大肠杆菌E. Coli 0-157和淋巴瘤细胞YAC-1的标记研究。在第四章中,主要以工业溶剂N-235为溶剂,利用高温注射法制备了低成本高效黄光-红光发射的CdZnSe合金量子点、CdSe/ZnSe以及CdZnS和ZnS包覆的核壳结构量子点,量子点的荧光量子效率达到94%。系统研究了量子点结构与包覆条件对发光性质的影响,并对生长机制做了合理探讨。探索了一系列高温下合成了幻数尺寸量子点的影响因素,通过改变表面配体浓度,优化反应温度制备了幻数尺寸的CdSe/ZnSe和CdZnSe量子点。最后利用SiO2对量子点进行了包覆并得到了单颗粒分散的量子点,SiO2包覆的量子点溶于水和多种缓冲溶液并保持长时间的稳定性。在第五章中,主要对本论文的工作进行了总结,分析和讨论了现有研究工作存在的问题,并对未来的工作进行了展望。总之,基于本论文的研究工作,实现了基于非注入合成制备高效绿色发光量子点,基于高温热分解反应制备了荧光量子产率达94%的黄红色发光量子点,证明了通过合理调节加热速率及前驱体浓度或表面配体用量及反应温度能够在低温非注入合成和高温热分解反应中制备幻数尺寸量子点,通过调节反应温度与硅烷浓度可以实现单分散量子点的Si02包覆,本项研究对深入了解量子点合成中的动力学过程及拓展现有量子点应用范围具有极其重要的意义。
[Abstract]:Colloidal quantum dots can attract so much attention because of their potential application in biomarkers, photovoltaic, lighting, laser, photocatalysis, thermoelectric and a new generation of micro-electronic devices, which is the result of an in-depth study of its optimization and photo-electrical properties over the last few decades. In all semiconductor quantum dot materials, CdSe, as a typical material in which CdSe has a number of first in a colloidal quantum dot study, comprises a first quantum dot having a total size distribution of less than 10% by the first chemical synthesis, The first is a colloidal quantum dot to which a biological molecule is attached and used for a biological marker, a first material for comparing the absorption and luminescence experimental data with the theoretical calculated energy band structure data, and the like. The components and structures of the ternary alloy semiconductor quantum dots are more complex than the binary II-VI group semiconductor quantum dots, but their photoelectric properties can be adjusted by changing the semiconductor components, so that the absorption can be improved while the carrier transport performance is improved, to facilitate the application in a particular practice. In this paper, the quantum dots and the alloy quantum dots of the CdSe-based nuclear shell structure are mainly used as the research object, and a series of high-efficiency light-emitting quantum dots are prepared by adopting a non-injection method, and a plurality of alloys and a nuclear shell structure quantum dot are prepared by the high-temperature injection method; The synthesis of the quantum dots of the magic number of different systems is studied, the multi-mode light-emitting quantum dot material is constructed, the growth mechanism and the light-emitting mechanism of the quantum dots are discussed, the phase transfer method of the quantum dots is studied, and the application of the quantum dot fluorescent probe is explored. The specific research contents are as follows: In the first chapter, the properties, structure and light-emitting mechanism of the quantum dots are briefly introduced, and the research progress and existing problems in the synthesis and application of the semiconductor quantum dots in recent years are further summarized. The topic meaning and main research contents of this thesis are put forward. In the second chapter, CdSe quantum dots were synthesized by a non-injection method using ODE as solvent, Se powder and Cd (SA) 2 as raw materials. The formation of magic-sized quantum dots can be observed under appropriate conditions, and these quantum dots exhibit an unusual continuous growth model at relatively low temperatures. The growth kinetics of CdSe quantum dots is studied by absorption spectrum and luminescence spectrum. The results show that the solvent of Se powder is the limiting factor of the nucleation rate and the nucleation rate. Compared with the traditional high-temperature thermal decomposition method, the growth of the quantum dots in the non-injection synthesis has different dynamic characteristics compared with the traditional high-temperature thermal decomposition method. the quantum dots synthesized by the non-injection method have high crystallinity, the fluorescence quantum yield of the quantum dots is increased to 63 percent by using the ZnS passivation coating, and if a layer of ZnSe transition layer is added between the CdSe core and the ZnS passivation layer, The fluorescence quantum yield of the CdSe/ ZnSe/ ZnS quantum dots with the nuclear shell structure can be up to 74%, which is comparable to that of the quantum dots prepared by many high-temperature thermal decomposition methods. Then, the quantum dots of the multi-mode light-emitting CdSe/ CdS/ ZnS core shell structure are prepared by in-situ injection synthesis and subsequent coating, and the light-emitting properties of the multi-mode light-emitting CdSe/ CdS/ ZnS core shell structure are systematically studied. In the third chapter, the quantum dot of CdTeSe-based nuclear shell structure with wide emission spectrum and different morphology was studied by high-temperature injection method. The effect of injection process and reaction temperature was studied, and the mechanism of growth was discussed. The effect of quantum dot luminescence on the excitation wavelength dependence of different passivation methods was studied by comparing the 3-D PL spectra of the spherical CdTeSe quantum dots and the quantum dots of different core shell structures. Similar to the structure of the ZnSe shell layer in the CdSe/ ZnSe/ ZnS quantum dots, the ZnSe layer in the CdTeSe/ ZnSe/ ZnS also plays an important role in providing a smooth interface and a slowly varying energy band structure. Finally, the quantum dots of the nuclear shell structure emitted from red light were transferred to the aqueous phase and successfully used to study the labeling of E. Coli 0-157 and the lymphoma cell YAC-1. In the fourth chapter, the quantum dots of CdZnSe, CdSe/ ZnSe and CdZnS and ZnS-coated nuclear shell structures with low cost and high efficiency yellow light-red light are prepared by high-temperature injection, and the quantum efficiency of the quantum dots is 94%. The effect of quantum dot structure and coating conditions on the properties of light-emitting was studied, and the mechanism of growth was discussed. In this paper, the influence factors of the quantum dots of the magic number are synthesized under a series of high temperatures, and the CdSe/ ZnSe and CdZnSe quantum dots of the magic number size are prepared by changing the surface ligand concentration and optimizing the reaction temperature. and finally, the quantum dots with the single particle dispersion are coated by using the SiO2, and the quantum dots coated by the SiO2 are dissolved in water and a plurality of buffer solutions and are kept for a long time. In the fifth chapter, the work of the thesis is summarized, the problems existing in the existing research work are analyzed and discussed, and the future work is expected. In conclusion, based on the research work of this paper, a high-efficiency green light emitting quantum dot is prepared based on the non-injection synthesis, and the yellow-red light emitting quantum dot with the fluorescence quantum yield of 94% is prepared based on the high-temperature thermal decomposition reaction. in that invention, by reasonably adjust the heating rate and the precursor concentration or the amount of the surface ligand and the reaction temperature, the magic number size quantum dot can be prepared in the low-temperature non-injection synthesis and the high-temperature thermal decomposition reaction, and the Si02 coating of the monodisperse quantum dot can be realized by adjusting the reaction temperature and the silane concentration, This study is of great significance to the deep understanding of the dynamic process in the synthesis of quantum dots and to extend the application range of the existing quantum dots.
【学位授予单位】:山东大学
【学位级别】:博士
【学位授予年份】:2015
【分类号】:O611.2

【共引文献】

相关硕士学位论文 前1条

1 谢芸芸;中国黄土地区地下水高砷形成机制研究[D];合肥工业大学;2013年



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