Surface ligands play a critical role in determining the properties of quantum dots (QDs). Long and short chain amines, thiols, phosphines, carboxylic acids and alkenes are commonly utilized as surface passivating ligands for nanocrystals, which prevent surface oxidation and impart dispersability in solvents. We recently reported a facile synthetic method for the preparation of amine passivated Ge QDs. The as-prepared Ge QDs were observed to be non-emissive in the expected near-IR region. In addition, extended exposure to ambient conditions resulted in their aggregation due to oxidation. We attribute these observations to incomplete passivation of the Ge nanocrystal surface by the amines.  Long chain thiols have been shown in literature as a good passivating ligand for Ge nanowires and in this work we have explored dodecanethiol as a passivating ligand for the Ge QDs. Oleylamine present in the parent Ge QDs were removed by treatment with hydrazine solutions in acetonitrile and thiol passivation was achieved by subsequent heating with dodecanethiol at 80-120 �C for about 8-16 h. The exchange of the surface ligand has been confirmed by FT-IR spectroscopy. We are currently investigating the thiol capped Ge QDs by surface photovoltage spectroscopy to evaluate their band-gap and the results will be discussed in the presentation.

Preparation and properties of thiol-capped germanium nanocrystals

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.