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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 5671-5678 |
| Number of pages | 8 |
| Journal | Journal of Physical Chemistry C |
| Volume | 119 |
| Issue number | 10 |
| DOIs | |
| State | Published - Mar 12 2015 |
Fingerprint
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Energy(all)
Cite this
Probing electronics as a function of size and surface of colloidal germanium nanocrystals. / Holmes, Alexandra L.; Hütges, Jeanette; Reckmann, Anna; Muthuswamy, Elayaraja; Meerholz, Klaus; Kauzlarich, Susan M.
In: Journal of Physical Chemistry C, Vol. 119, No. 10, 12.03.2015, p. 5671-5678.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Probing electronics as a function of size and surface of colloidal germanium nanocrystals
AU - Holmes, Alexandra L.
AU - Hütges, Jeanette
AU - Reckmann, Anna
AU - Muthuswamy, Elayaraja
AU - Meerholz, Klaus
AU - Kauzlarich, Susan M.
PY - 2015/3/12
Y1 - 2015/3/12
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=84924565542&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84924565542&partnerID=8YFLogxK
U2 - 10.1021/jp511929v
DO - 10.1021/jp511929v
M3 - Article
AN - SCOPUS:84924565542
VL - 119
SP - 5671
EP - 5678
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 10
ER -