钝化有机配体的形貌
Morphology of passivating organic ligands around a nanocrystal
摘要：
半导体纳米晶体是一类很有前途的材料，用于各种新型光电子器件，因为它们的许多性质，如电子间隙和导电性，可以控制。这种控制大部分是通过有机配体壳层，通过控制分子的大小和与其他物体的距离来实现的。在这里，我们模拟配体包覆的CdSe纳米晶体使用原子分子动力学，允许有关配体壳层的新的结构细节的决议。我们表明，表面上的配位体可以平放，形成一个高度各向异性的“湿头发”层，而不是通常认为的“尖刺球”的外观。我们讨论这如何可以引起一个点到点的包装距离的一个配体的长度，因为配体壳的厚度被减少到大约一半的配体长度的系统尺寸在这里考虑，这些距离意味着点和附近的物体之间的能量和电荷转移速率将被增强由于薄于预期的配体壳。我们的模型预测了一个非线性缩放的配体壳层厚度的配位体过渡从“尖刺”到“湿头发”。我们验证了这种缩放使用TEM上的硫化铅纳米阵列，确认该理论给出了一个定性正确的图片的配体壳层厚度的胶体量子点。
英文摘要：
Semiconductor nanocrystals are a promising class of materials for a variety of novel optoelectronic devices, since many of their properties, such as the electronic gap and conductivity, can be controlled. Much of this control is achieved via the organic ligand shell, through control of the size of the nanocrystal and the distance to other objects. We here simulate ligand-coated CdSe nanocrystals using atomistic molecular dynamics, allowing for the resolution of novel structural details about the ligand shell. We show that the ligands on the surface can lie flat to form a highly anisotropic 'wet hair' layer as opposed to the 'spiky ball' appearance typically considered. We discuss how this can give rise to a dot-to-dot packing distance of one ligand length since the thickness of the ligand shell is reduced to approximately one-half of the ligand length for the system sizes considered here; these distances imply that energy and charge transfer rates between dots and nearby objects will be enhanced due to the thinner than expected ligand shell. Our model predicts a non-linear scaling of ligand shell thickness as the ligands transition from 'spiky' to 'wet hair'. We verify this scaling using TEM on a PbS nanoarray, confirming that this theory gives a qualitatively correct picture of the ligand shell thickness of colloidal quantum dots.
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