【作者】 王春雷；

【导师】 杨柏；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2008， 博士

【摘要】 本论文围绕水相纳米晶生长机理这一主题展开了以下研究工作:第一,从分子间相互作用力入手分析油相与水相纳米晶的差异,研究静电力对水相纳米晶成核及生长过程的影响,并以此为基础建立了水相纳米晶的双电层结构模型。第二,以纳米晶周围环境—纳米晶双电层结构—纳米晶生长规律为主线,系统研究了各种实验条件对纳米晶周围环境、纳米晶结构及其生长规律的影响,深化了对水相纳米晶生长机理的认识。第三,发明了柠檬酸钠辅助制备水相纳米晶的新方法,该法不仅拓展了水相纳米晶的制备,也突破了巯基水相法配体与单体比例调控范围的限制,为深入研究配体、配体层与纳米晶生长规律的关系提供了新思路。第四,通过合理选择配体与前驱体组合以及适当的实验条件来调控纳米晶的生长过程,设计制备了CdTe/CdS核壳纳米晶以及CdS亚微米微球,为利用水相法设计制备结构复杂、功能多样的纳米晶开辟了新途径。更多还原

【Abstract】 Semiconductor nanocrystals (NCs) have attracted great fundamental and technical interests in recent years. Among various physical and chemical routes of NCs preparation, the colloidal chemistry method is the best one for synthesis NCs with high quantum yields QYs, narrow dispersion, desired shape and controllable surface functionality. Colloidal method also makes it possible to synthesize NCs alternatively in aqueous solution and non-aqueous media. Based on the investigation of non-aqueous NCs, the diffusion controlled growth mechanism of NCs is gradually revealed. In parallel with the success of non-aqueous synthesis routes, aqueous methods have also been developed to prepare II-VI NCs, especially CdTe NCs. Since the first reports of 1-thioglycerol stabilized CdTe NCs in aqueous media, various thiol ligands are used for aqueous CdTe NCs. However, less works are focus on the the growth mechanism of aqueous NCs due to the complexity of aqueous system. This has become a great obstacle for further investigation of aqueous NCs. In this paper, our aim is to build up the structure model of aqueous NCs and investigate their growth mechanism. According to such model, we also design some more complex structure of aqueous NCs, such as aqueous CdTe/CdS core-shell NCs and sub-micrometer CdS spheres.In the second chapter, we mainly investigate the relationship between electrostatic repulsion and the process of NCs nucleation and growth. According to the knowledge of colloidal chemistry, we also build up the double layer model of aqueous NCs. Namely NCs compose of core, ligand shell, adsorption layer, diffusion layer from inside to outside. The various experimental conditions, such as concentration, ions strength, pH are expected to affect the diffusion layer, thus the growth process of NCs.In the third chapter, we mainly investigate the effect of ligand shell on the growth of NCs. To study the effect of ligand in a large extent, we also develop a new sodium citrate assisted method to prepared CdTe NCs.In the forth chapter, we are focus on the adsorption layer of NCs. Such layer is especially important at room temperature. During storage at room temperature, the excess ligands or cadmium-ligands compounds in solution are preferentially adsorbed on adsorption layer before they diffuse into the ligand shell. Though the adsorption layer does not directly determine the optical property of NCs, it can affect the diffusion process of free ligands or cadmium-ligands compounds into the ligand shell. The treatments of dilution, concentration, storage, and pH adjustment affect the thickness of adsorption layer as well as the ligand diffusion into ligand shell, leading to diverse optical behavior of NCs.Based on above knowledge of NCs structure model and growth mechanism,in chapter five and six, we design some complex structure of NCs, namely the aqueous CdTe/CdS core-shell NCs and CdS sub-micrometer spheres.更多还原