Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States.
J Am Chem Soc. 2021 Jan 27;143(3):1251-1266. doi: 10.1021/jacs.0c10658. Epub 2021 Jan 14.
Semiconductor nanocrystals exhibit attractive photophysical properties for use in a variety of applications. Advancing the efficiency of nanocrystal-based devices requires a deep understanding of the physical defects and electronic states that trap charge carriers. Many of these states reside at the nanocrystal surface, which acts as an interface between the semiconductor lattice and the molecular capping ligands. While a detailed structural and electronic understanding of the surface is required to optimize nanocrystal properties, these materials are at a technical disadvantage: unlike molecular structures, semiconductor nanocrystals lack a specific chemical formula and generally must be characterized as heterogeneous ensembles. Therefore, in order for the field to improve current nanocrystal-based technologies, a creative approach to gaining a "molecular-level" picture of nanocrystal surfaces is required. To this end, an expansive toolbox of experimental and computational techniques has emerged in recent years. In this Perspective, we critically evaluate the insight into surface structure and reactivity that can be gained from each of these techniques and demonstrate how their strategic combination is already advancing our molecular-level understanding of nanocrystal surface chemistry.
半导体纳米晶体在各种应用中表现出吸引人的光物理性质。为了提高基于纳米晶体的器件的效率，需要深入了解捕获电荷载流子的物理缺陷和电子态。这些状态中的许多存在于纳米晶表面，纳米晶表面作为半导体晶格和分子覆盖配体之间的界面。虽然需要对表面进行详细的结构和电子理解来优化纳米晶体的性质，但这些材料在技术上处于劣势：与分子结构不同，半导体纳米晶体没有特定的化学式，通常必须作为异质混合物进行表征。因此，为了改进当前基于纳米晶体的技术，需要创造性地采用一种方法来获得纳米晶表面的“分子水平”图像。为此，近年来出现了广泛的实验和计算技术工具包。在本观点中，我们批判性地评估了可以从这些技术中的每一种技术中获得的表面结构和反应性的见解，并展示了它们的战略组合如何已经在推进我们对纳米晶表面化学的分子水平理解。
