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Title: Quantitative interpretation of the transition voltages in gold-poly(phenylene) thiol-gold molecular junctions

The transition voltage of three different asymmetric Au/poly(phenylene) thiol/Au molecular junctions in which the central molecule is either benzene thiol, biphenyl thiol, or terphenyl thiol is investigated by first-principles quantum transport simulations. For all the junctions, the calculated transition voltage at positive polarity is in quantitative agreement with the experimental values and shows weak dependence on alterations of the Au-phenyl contact. When compared to the strong coupling at the Au-S contact, which dominates the alignment of various molecular orbitals with respect to the electrode Fermi level, the coupling at the Au-phenyl contact produces only a weak perturbation. Therefore, variations of the Au-phenyl contact can only have a minor influence on the transition voltage. These findings not only provide an explanation to the uniformity in the transition voltages found for π-conjugated molecules measured with different experimental methods, but also demonstrate the advantage of transition voltage spectroscopy as a tool for determining the positions of molecular levels in molecular devices.
Authors:
; ;  [1] ;  [2]
  1. Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871 (China)
  2. School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2 (Ireland)
Publication Date:
OSTI Identifier:
22251417
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 139; Journal Issue: 19; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BENZENE; BIPHENYL; COUPLING; DISTURBANCES; ELECTRIC POTENTIAL; FERMI LEVEL; PERTURBATION THEORY; SIMULATION; SPECTROSCOPY; THIOLS