Graphene as a Promising Electrode for Low-Current Attenuation in Nonsymmetric Molecular Junctions.
We have measured the single-molecule conductance of 1,n-alkanedithiol molecular bridges (n = 4, 6, 8, 10, 12) on a graphene substrate using scanning tunneling microscopy (STM)-formed electrical junctions. The conductance values of this homologous series ranged from 2.3 nS (n = 12) to 53 nS (n = 4), with a decay constant βnof 0.40 per methylene (-CH2) group. This result is explained by a combination of density functional theory (DFT) and Keldysh-Green function calculations. The obtained decay, which is much lower than the one obtained for symmetric gold junctions, is related to the weak coupling at the molecule-graphene interface and the electronic structure of graphene. As a consequence, we show that using graphene nonsymmetric junctions and appropriate anchoring groups may lead to a much-lower decay constant and more-conductive molecular junctions at longer lengths.
Department of Chemistry, University of Liverpool , Liverpool, L69 7ZD U.K.
Qian
Q
Zhang
Department of Chemistry and Chemical Engineering, Chongqing University , Chongqing, 400030, China.
Longlong
L
Liu
Department of Chemistry, University of Liverpool , Liverpool, L69 7ZD U.K.
Shuhui
S
Tao
Congyi
C
Wang
Cezhou
C
Zhao
SPEC, CEA, CNRS, Université Paris-Saclay , CEA Saclay 91191 Gif-sur-Yvette Cedex, France.|Departamento de Electrónica y Tecnología de Computadores, Universidad de Granada , Campus de Fuente Nueva & CITIC, Campus de Aynadamar 18071, Granada, Spain.
César
C
González
SPEC, CEA, CNRS, Université Paris-Saclay , CEA Saclay 91191 Gif-sur-Yvette Cedex, France.
Yannick J
YJ
Dappe
Department of Chemistry, University of Liverpool , Liverpool, L69 7ZD U.K.
Richard J
RJ
Nichols
Department of Chemistry, University of Liverpool , Liverpool, L69 7ZD U.K.
Li
L
Yang
Graphene-based electrode; alkanedithiol; charge transport; density functional theory; single molecule conductance