An in-depth understanding of the growth mechanism of nanocrystals (NCs) is of great significance for shape control of colloidal semiconductor nanostructures. In this study, we elucidate the formation mechanism of anisotropic CdSe NCs by systematically investigating their growth in the presence of dioctylamine and carboxylate ligands with different chain lengths. A morphological transition from nanotubes and nanosheets to irregular nanorods and finally to nanodots was observed when the carbon number of the carboxylate ligands increased from 2 to 18. The traditional understanding of the growth of anisotropic CdSe nanostructures is mainly based on the monomer addition, which is difficult to explain the phenomena observed. We found that both short- and long-chain carboxylate ligands can lead to the anisotropic growth of CdSe NCs by attachment of early-formed building blocks, which is a nonclassical particle-mediated growth approach. The use of different carboxylate ligands plays a key role in the formation of different building blocks by affecting the local monomer supersaturation. We provide both experimental observations and first-principles simulations to support this hypothesis.

中文翻译：

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洞悉各向异性CdSe纳米晶体的生长：固有不同的构建基块的附着。

深入了解纳米晶体（NCs）的生长机理对于胶体半导体纳米结构的形状控制具有重要意义。在这项研究中，我们通过系统地研究在不同链长的二辛胺和羧酸盐配体的存在下各向异性CdSe NCs的形成机理。当羧酸盐配体的碳原子数从2增加到18时，观察到了从纳米管和纳米片到不规则纳米棒，最后到纳米点的形态学转变。对各向异性CdSe纳米结构生长的传统理解主要是基于单体的添加，即难以解释观察到的现象。我们发现短链和长链羧酸盐配体都可以通过附着早期形成的结构单元而导致CdSe NCs的各向异性生长，这是一种非经典的粒子介导的生长方法。通过影响局部单体过饱和，使用不同的羧酸盐配体在形成不同结构单元中起关键作用。我们提供实验观察和第一性原理模拟，以支持这一假设。