Weir Michael P, Toolan Daniel T W, Kilbride Rachel C, Penfold Nicholas J W, Washington Adam L, King Stephen M, Xiao James, Zhang Zhilong, Gray Victor, Dowland Simon, Winkel Jurjen, Greenham Neil C, Friend Richard H, Rao Akshay, Ryan Anthony J, Jones Richard A L
Department of Physics and Astronomy , The University of Sheffield , Sheffield S3 7RH , United Kingdom.
Department of Chemistry , The University of Sheffield , Sheffield S3 7HF , United Kingdom.
J Phys Chem Lett. 2019 Aug 15;10(16):4713-4719. doi: 10.1021/acs.jpclett.9b01008. Epub 2019 Aug 6.
Nanocrystal quantum dots are generally coated with an organic ligand layer. These layers are a necessary consequence of their chemical synthesis, and in addition they play a key role in controlling the optical and electronic properties of the system. Here we describe a method for quantitative measurement of the ligand layer in 3 nm diameter lead sulfide-oleic acid quantum dots. Complementary small-angle X-ray and neutron scattering (SAXS and SANS) studies give a complete and quantitative picture of the nanoparticle structure. We find greater-than-monolayer coverage of oleic acid and a significant proportion of ligand remaining in solution, and we demonstrate reversible thermal cycling of the oleic acid coverage. We outline the effectiveness of simple purification procedures with applications in preparing dots for efficient ligand exchange. Our method is transferrable to a wide range of colloidal nanocrystals and ligand chemistries, providing the quantitative means to enable the rational design of ligand-exchange procedures.
纳米晶体量子点通常包覆有一层有机配体层。这些配体层是其化学合成的必然产物，此外，它们在控制系统的光学和电子性质方面起着关键作用。在此，我们描述了一种定量测量直径为3纳米的硫化铅 - 油酸量子点中配体层的方法。互补的小角X射线和中子散射（SAXS和SANS）研究给出了纳米颗粒结构完整且定量的图像。我们发现油酸的覆盖量大于单层，并且有相当比例的配体残留在溶液中，并且我们证明了油酸覆盖量的可逆热循环。我们概述了简单纯化程序在制备用于高效配体交换的量子点方面的有效性。我们的方法可转移到广泛的胶体纳米晶体和配体化学体系中，提供了定量手段以实现配体交换程序的合理设计。
