Revealing the role of anchoring groups in the electrical conduction through single-molecule junctions.

A combined experimental and theoretical study is presented revealing the influence of metal-molecule coupling on electronic transport through single-molecule junctions. Transport experiments through tolane molecules attached to gold electrodes via thiol, nitro, and cyano anchoring groups are performed. By fitting the experimental current-voltage characteristics to a single-level tunneling model, we extract both the position of the molecular orbital closest to the Fermi energy and the strength of the metal-molecule coupling. The values found for these parameters are rationalized with the help of density-functional-theory-based transport calculations. In particular, these calculations show that the anchoring groups determine the junction conductance by controlling not only the strength of the coupling to the metal but also the position of the relevant molecular energy levels.

[1]  M. Steigerwald,et al.  Contact chemistry and single-molecule conductance: a comparison of phosphines, methyl sulfides, and amines. , 2007, Journal of the American Chemical Society.

[2]  J. Gilman,et al.  Nanotechnology , 2001 .

[3]  E. Scheer,et al.  Conductance of individual C60 molecules measured with controllable gold electrodes , 2007 .

[4]  T. Bjørnholm,et al.  Molecular electronics with single molecules in solid-state devices. , 2009, Nature nanotechnology.

[5]  Yuyuan Tian,et al.  Measurement of Single-Molecule Resistance by Repeated Formation of Molecular Junctions , 2003, Science.

[6]  K. Müller.  Effect of the atomic configuration of gold electrodes on the electrical conduction of alkanedithiol molecules , 2006 .

[7]  O. Sankey,et al.  Electron transport through single alkane molecules with different contact geometries on gold , 2006 .

[8]  Amine-linked single-molecule circuits: systematic trends across molecular families. , 2008, Journal of physics. Condensed matter : an Institute of Physics journal.

[9]  Michel Devoret,et al.  Adjustable nanofabricated atomic size contacts , 1996 .

[10]  M. Steigerwald,et al.  Electronics and chemistry: varying single-molecule junction conductance using chemical substituents. , 2007, Nano letters.

[11]  E. Scheer,et al.  Point-contact spectroscopy on aluminium atomic-size contacts: longitudinal and transverse vibronic excitations , 2009 .

[12]  N. J. Tao,et al.  Electron transport in molecular junctions , 2006, Nature nanotechnology.

[13]  Christian A. Martin,et al.  Fullerene-based anchoring groups for molecular electronics. , 2008, Journal of the American Chemical Society.

[14]  Resonant tunnelling through a C(60) molecular junction in a liquid environment. , 2005, Nanotechnology.

[15]  Comparative study of anchoring groups for molecular electronics: structure and conductance of Au-S-Au and Au-NH(2)-Au junctions. , 2008, Journal of physics. Condensed matter : an Institute of Physics journal.

[16]  S. Louie,et al.  Amine-gold linked single-molecule circuits: experiment and theory. , 2007, Nano letters.

[17]  J. Cuevas,et al.  Cluster-based density-functional approach to quantum transport through molecular and atomic contacts , 2008, 0806.4173.

[18]  A. Majumdar,et al.  Identifying the length dependence of orbital alignment and contact coupling in molecular heterojunctions. , 2009, Nano letters.

[19]  Hans W. Horn,et al.  Fully optimized contracted Gaussian basis sets for atoms Li to Kr , 1992 .

[20]  M. Steigerwald,et al.  Single-molecule circuits with well-defined molecular conductance. , 2006, Nano letters.

[21]  N. D. Lang,et al.  Measurement of the conductance of a hydrogen molecule , 2002, Nature.

[22]  J. Perdew,et al.  Density-functional approximation for the correlation energy of the inhomogeneous electron gas. , 1986, Physical review. B, Condensed matter.

[23]  Colin Nuckolls,et al.  Dependence of single-molecule junction conductance on molecular conformation , 2006, Nature.

[24]  Zhenyu Li,et al.  Nature of well-defined conductance of amine-anchored molecular junctions : Density functional calculations , 2007 .

[25]  Electrical conductance of atomic contacts in liquid environments. , 2004, Small.

[26]  Andreas Arnold,et al.  Charge transport in single Au / alkanedithiol / Au junctions: coordination geometries and conformational degrees of freedom. , 2008, Journal of the American Chemical Society.

[27]  M. Ford,et al.  Rectification in donor–acceptor molecular junctions , 2008, Journal of physics. Condensed matter : an Institute of Physics journal.

[28]  S. J. van der Molen,et al.  Interpretation of transition voltage spectroscopy. , 2009, Nano letters.

[29]  End group effect on electrical transport through individual molecules: A microscopic study , 2003, cond-mat/0312495.

[30]  Ranganathan Shashidhar,et al.  Tuning current rectification across molecular junctions , 2004 .

[31]  Mark A Ratner,et al.  Spectroscopic tracking of molecular transport junctions generated by using click chemistry. , 2009, Angewandte Chemie.

[32]  H. B. Weber,et al.  Statistical approach to investigating transport through single molecules. , 2007, Physical review letters.

[33]  Hans W. Horn,et al.  ELECTRONIC STRUCTURE CALCULATIONS ON WORKSTATION COMPUTERS: THE PROGRAM SYSTEM TURBOMOLE , 1989 .

[34]  Sergey Kafanov,et al.  Electronic transport in single molecule junctions: control of the molecule-electrode coupling through intramolecular tunneling barriers. , 2008, Nano letters.

[35]  Zhifeng Huang,et al.  Effect of anchoring groups on single-molecule conductance: comparative study of thiol-, amine-, and carboxylic-acid-terminated molecules. , 2006, Journal of the American Chemical Society.

[36]  R. Rosenfeld.  Nature , 2009, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[37]  A. Majumdar,et al.  Probing the chemistry of molecular heterojunctions using thermoelectricity. , 2008, Nano letters.

[38]  Yuyuan Tian,et al.  Conductance of single alkanedithiols: conduction mechanism and effect of molecule-electrode contacts. , 2006, Journal of the American Chemical Society.

[39]  M. Steigerwald,et al.  Formation and evolution of single-molecule junctions. , 2009, Physical review letters.

[40]  Marcel Mayor,et al.  Electric current through a molecular rod-relevance of the position of the anchor groups. , 2003, Angewandte Chemie.