Universität zu Köln

Holmes, Alexandra L., Huetges, Jeanette, Reckmann, Anna, Muthuswamy, Elayaraja, Meerholz, Klaus ORCID: 0000-0001-7450-4672 and Kauzlarich, Susan M. (2015). Probing Electronics as a Function of Size and Surface of Colloidal Germanium Nanocrystals. J. Phys. Chem. C, 119 (10). S. 5671 - 5679. WASHINGTON: AMER CHEMICAL SOC. ISSN 1932-7447

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Abstract

Inorganic semiconductor nanoparticles are of significant interest for applications that benefit from their size-dependent properties. The work presented here focuses on the characterization of solution-based microwave synthesized Ge nanocrystals (NCs). Three differently capped Ge NCs were investigated: oleylamine (OAM), dodecanethiol (DDT), and a functionalized N4,N4,N4',N4'-tetraphenylbiphenyl-4,4'-diamine (TPD) ligand, which is commonly used as hole-transporting units. The optical gaps followed the expected trend for quantum confinement; however, the absolute value depended upon the ligand. We found that the DDT-capped Ge NCs feature consistently larger bandgaps than OAM-capped Ge NCs of a similar size. Cyclic voltammetry (CV) was used to determine the valence band energy for OAM-capped Ge NCs, and the conduction band energy was estimated from the optical gap. By contrast, DDT-capped Ge NCs and the OAM/DDT-capped Ge NCs did not exhibit an oxidative signal in the cyclic voltammetry. This was attributed to the removal of surface defects of OAM-capped Ge NCs through stronger Ge-S surface bonds. TPD-capped Ge NCs were investigated and showed a shift to slightly higher oxidation potential compared with the free ligand and bandgap values in between that of the OAM-capped and DDT-capped Ge NCs. The higher oxidation potential is attributed to TPD orientation, and the bandgap value reflects the lower number of Ge-S bonds on the surface due to ligand sterics.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Holmes, Alexandra L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Huetges, Jeanette UNSPECIFIED UNSPECIFIED UNSPECIFIED Reckmann, Anna UNSPECIFIED UNSPECIFIED UNSPECIFIED Muthuswamy, Elayaraja UNSPECIFIED UNSPECIFIED UNSPECIFIED Meerholz, Klaus UNSPECIFIED orcid.org/0000-0001-7450-4672 UNSPECIFIED Kauzlarich, Susan M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-409874
DOI:	10.1021/jp511929v
Journal or Publication Title:	J. Phys. Chem. C
Volume:	119
Number:	10
Page Range:	S. 5671 - 5679
Date:	2015
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	1932-7447
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Physical Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language QUANTUM CONFINEMENT; CYCLIC VOLTAMMETRY; NANOPARTICLES; ELECTROCHEMISTRY; MONOLAYERS; CHEMISTRY; FILMS; DOTS; GAP; GE Multiple languages Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/40987