First-principles investigation on the electronic efficiency and binding energy of the contacts formed by graphene and poly-aromatic hydrocarbon anchoring groups
Citation:
Li, Y. Tu, X. Wang, H. Sanvito, S. Hou, S., First-principles investigation on the electronic efficiency and binding energy of the contacts formed by graphene and poly-aromatic hydrocarbon anchoring groups, Journal of Chemical Physics, 142, 16, 2015, 164701-Download Item:
1.4918738.pdf (PDF) 2.176Mb
Abstract:
The electronic e
ffi
ciency and binding energy of contacts formed between graphene electrodes and
poly-aromatic hydrocarbon (PAH) anchoring groups have been investigated by the non-equilibrium
Green’s function formalism combined with density functional theory. Our calculations show that PAH
molecules always bind in the interior and at the edge of graphene in the AB stacking manner, and
that the binding energy increases following the increase of the number of carbon and hydrogen atoms
constituting the PAH molecule. When we move to analyzing the electronic transport properties of
molecular junctions with a six-carbon alkyne chain as the central molecule, the electronic e
ffi
ciency
of the graphene-PAH contacts is found to depend on the energy gap between the highest occupied
molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the correspond-
ing PAH anchoring group, rather than its size. To be specific, the smaller is the HOMO-LUMO gap
of the PAH anchoring group, the higher is the electronic e
ffi
ciency of the graphene-PAH contact.
Although the HOMO-LUMO gap of a PAH molecule depends on its specific configuration, PAH
molecules with similar atomic structures show a decreasing trend for their HOMO-LUMO gap as
the number of fused benzene rings increases. Therefore, graphene-conjugated molecule-graphene
junctions with high-binding and high-conducting graphene-PAH contacts can be realized by choosing
appropriate PAH anchor groups with a large area and a small HOMO-LUMO gap.
Author's Homepage:
http://people.tcd.ie/sanvitosDescription:
PUBLISHED
Author: SANVITO, STEFANO
Type of material:
Journal ArticleCollections:
Series/Report no:
Journal of Chemical Physics142
16
Availability:
Full text availableKeywords:
HOMO-LUMO gapDOI:
http://dx.doi.org/10.1063/1.4918738Licences: