Issue 9, 2019

The dynamic surface chemistry of colloidal metal chalcogenide quantum dots

Abstract

The chemical species (ligands) at the surface of colloidal inorganic semiconductor nanocrystals (QDs) mediate their interactions with the surroundings. The solvation of the QDs reflects a subtle interplay between ligand–solvent and ligand–ligand interactions, which eventually compete with the coordination of the ligands at the QD surface. The QD surface coordination and solvation are indeed fundamental to preserve their optoelectronic properties and to foster the effective application of QD-based inks and nanocomposites. Here we investigate such ligand interactions by exploiting diffusion ordered NMR spectroscopy (DOSY), which is suggested as an essential complement to spectral line width analysis. To this end, we use colloidal metal chalcogenide (CdS, CdSe, and PbS) QDs with (metal-)oleate ligands at their surface in several solvents exhibiting different viscosities and polarities. We demonstrate that the ligand shell is dynamically bound to the metal chalcogenide QDs, and is thus in equilibrium between the QD surface and the surrounding solvent. Such dynamic equilibria depend on ligand–solvent interactions, which are more prominent in aliphatic, rather polar solvents that favor the solvation of the ligands and, as a consequence, their displacement from the QD surface. In addition, the ligand–ligand interactions, which are more relevant for larger QDs, contribute to the stabilization of the ligand bonding at the QD surface.

Graphical abstract: The dynamic surface chemistry of colloidal metal chalcogenide quantum dots

Supplementary files

Article information

Article type
Paper
Submitted
22 jul 2019
Accepted
29 jul 2019
First published
07 avg 2019
This article is Open Access
Creative Commons BY-NC license

Nanoscale Adv., 2019,1, 3639-3646

The dynamic surface chemistry of colloidal metal chalcogenide quantum dots

R. Grisorio, D. Quarta, A. Fiore, L. Carbone, G. P. Suranna and C. Giansante, Nanoscale Adv., 2019, 1, 3639 DOI: 10.1039/C9NA00452A

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