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Surface Derivatization of Nanocrystalline CdSe Semiconductors

Published online by Cambridge University Press:  15 February 2011

J.-K. Lee
Affiliation:
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
M. Kuno
Affiliation:
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
M. G. Bawendi
Affiliation:
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
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Abstract

CdSe quantum dots (QDs) with several different ligands were prepared by ligand exchange reactions of trioctylphosphine oxide (TOPO)/trioctylphosphine selenide (TOPSe) passivated QDs with an excess of new ligands, such as pyridine, 4-picoline, thiophenol, 4-(trifluoromethyl)-thiophenol, and tris(2-ethylhexyl)phosphate. We find that 85–90% of ligands passivating the surface of the QDs are the newly introduced capping species and 10–15% are native TOPO/TOPSe ligands, reflecting the incomplete exchange of the QD surface. Thermal gravimetric analysis (TGA) and quantitative proton NMR measurements show that on average only 30% of surface cadmium atoms are passivated by TOPO/TOPSe. Approximately 1/3 of these native ligands occupy sites too strongly bound to be replaced by ligand exchange reactions.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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