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

Type
Article

Authors
Wu, Kunlin
Bai, Meilin
Sanvito, Stefano
Hou, Shimin

KAUST Grant Number
FIC/2010/08

Online Publication Date
2013-11-19

Print Publication Date
2013-11-21

Date
2013-11-19

Abstract
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. © 2013 AIP Publishing LLC.

Citation
Wu K, Bai M, Sanvito S, Hou S (2013) Quantitative interpretation of the transition voltages in gold-poly(phenylene) thiol-gold molecular junctions. J Chem Phys 139: 194703. Available: http://dx.doi.org/10.1063/1.4830399.

Acknowledgements
This project was supported by the National Natural Science Foundation of China (Grant No. 61071012) and the MOST of China (Grant Nos. 2011CB933001 and 2013CB933404). S. S. thanks additional funding support from Science Foundation of Ireland (Grant No. 07/IN/I945), by KAUST (FIC/2010/08), and by CRANN.

Publisher
AIP Publishing

Journal
The Journal of Chemical Physics

DOI
10.1063/1.4830399

PubMed ID
24320340

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