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The potential and applicability of QDs is closely linked to their composition and synthesis. However, also the surface chemistry of QDs plays an essential role for the quality of the nanocrystals. Especially their photoluminescence and stability are strongly influenced by the nature of the ligand used and by ligand adsorption-desorption equilibria.[1] Not only for the exact evaluation of their application-relevant performance, but also for the integration of QDs into functional nanocomposites it is crucial to know the exact effect of the ligand shell on the properties of QDs.[2] Here, we present a comprehensive investigation of the surface chemistry of CdTe QDs capped with thioglycolic acid. By using and comparing different analytical methods, such as elemental analysis, thermogravimetric techniques, and a colorimetric test we can derive QD surface-property relationships, e.g. the correlation between the ligand concentration on the QD surface and the photoluminescence quantum yield. In conjunction with controlled QD aggregation and separation the analysis gives an insight into ligand binding processes. This study presents a first step towards establishing reliable methods for the design and characterization of nanoparticle surfaces, which is the main issue for assembling QDs into superstructures. [1] M. Grabolle, M. Spieles, V. Lesnyak, N. Gaponik, A. Eychmüller, U. Resch-Genger: Determination of the Fluorescence Quantum Yield of Quantum Dots: Suitable Procedures and Achievable Uncertainties. In: Analytical Chemistry, 2009, 81(15), 6285-6294 [2] N. Gaponik: Assemblies of thiol-capped nanocrystals as building blocks for use in nanotechnology. In: Journal of Materials Chemistry. 2010, 20(25), 5174-5181 |
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