Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Portrait of the potential barrier at metal–organic nanocontacts

Nature Materials volume 9, pages 320–323 (2010)Cite this article

Subjects

Abstract

Electron transport through metal–molecule contacts greatly affects the operation and performance of electronic devices based on organic semiconductors1,2,3,4 and is at the heart of molecular electronics exploiting single-molecule junctions5,6,7,8. Much of our understanding of the charge injection and extraction processes in these systems relies on our knowledge of the potential barrier at the contact. Despite significant experimental and theoretical advances a clear rationale of the contact barrier at the single-molecule level is still missing. Here, we use scanning tunnelling microscopy to probe directly the nanocontact between a single molecule and a metal electrode in unprecedented detail. Our experiments show a significant variation on the submolecular scale. The local barrier modulation across an isolated 4-[trans-2-(pyrid-4-yl-vinyl)] benzoic acid molecule bound to a copper(111) electrode exceeds 1 eV. The giant modulation reflects the interaction between specific molecular groups and the metal and illustrates the critical processes determining the interface potential. Guided by our results, we introduce a new scheme to locally manipulate the potential barrier of the molecular nanocontacts with atomic precision.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Get just this article for as long as you need it

$39.95

Learn more

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Potential barrier across the plane of a molecule–metal nanocontact.
Figure 2: Charge-transfer map of deprotonated PVBA absorbed on Cu(111).
Figure 3: Manipulation of the potential barrier by coordination bonding.

References

  1. Park, Y. D., Lim, J. A., Lee, H. S. & Cho, K. Interface engineering in organic transistors. Mater. Today 10, 46–54 (2007).

    Article  CAS  Google Scholar 

  2. Soubatch, S., Temirov, R. & Tautz, F. S. Fundamental interface properties in OFETs: Bonding, structure and function of molecular adsorbate layers on solid surfaces. Phys. Status Solidi A 205, 511–525 (2008).

    Article  CAS  Google Scholar 

  3. Friend, R. H. et al. Electroluminescence in conjugated polymers. Nature 397, 121–128 (1999).

    Article  CAS  Google Scholar 

  4. Janata, J. & Josowicz, M. Conducting polymers in electronic chemical sensors. Nature Mater. 2, 19–24 (2002).

    Article  Google Scholar 

  5. Nitzan, A. & Ratner, M. A. Electron transport in molecular wire junctions. Science 300, 1384–1389 (2003).

    Article  CAS  Google Scholar 

  6. Xu, B. & Tao, N. J. Measurement of single-molecule resistance by repeated formation of molecular junctions. Science 301, 1221–1223 (2003).

    Article  CAS  Google Scholar 

  7. Smit, R. H. M. et al. Measurement of the conductance of a hydrogen molecule. Nature 419, 906–909 (2002).

    Article  CAS  Google Scholar 

  8. Reed, M. A., Zhou, C., Muller, C. J., Burgin, T. P. & Tour, J. M. Conductance of a molecular junction. Science 278, 252–254 (1997).

    Article  CAS  Google Scholar 

  9. Ishii, H., Sugiyama, K., Ito, E. & Seki, K. Energy level alignment and interfacial electronic structures at organic/metal and organic/organic interfaces. Adv. Mater. 11, 605–625 (1999).

    Article  CAS  Google Scholar 

  10. Cahen, D. & Kahn, A. Electron energetics at surfaces and interfaces: Concept and experiments. Adv. Mater. 15, 271–277 (2003).

    Article  CAS  Google Scholar 

  11. Duhm, S. et al. Orientation-dependent ionization energies and interface dipoles in ordered molecular assemblies. Nature Mater. 7, 326–332 (2008).

    Article  CAS  Google Scholar 

  12. Seitsonen, A. P. et al. Density functional theory analysis of carboxylate-bridged diiron units in two-dimensional metal–organic grids. J. Am. Chem. Soc. 128, 5634–5635 (2006).

    Article  CAS  Google Scholar 

  13. Wandelt, K. Thin Metal Films and Gas Chemisorption 280 (Elsevier, 1987).

    Book  Google Scholar 

  14. Bagus, P. S., Staemmler, V. & Wöll, C. Exchangelike effects for closed-shell adsorbates: Interface dipole and work function. Phys. Rev. Lett. 89, 096104 (2002).

    Article  Google Scholar 

  15. Leung, T. C., Kao, C. L., Su, W. S., Feng, Y. J. & Chan, C. T. Relationship between surface dipole, work function and charge transfer: Some exceptions to an established rule. Phys. Rev. B 68, 195408 (2003).

    Article  Google Scholar 

  16. Velic, D., Hotzel, A., Wolf, M. & Ertl, G. Electronic states of the C6H6/Cu(111) system: Energetics, femtosecond dynamics, and adsorption morphology. J. Chem. Phys. 109, 9155–9165 (1998).

    Article  CAS  Google Scholar 

  17. De Renzi, V. et al. Metal work-function changes induced by organic adsorbates: A combined experimental and theoretical study. Phys. Rev. Lett. 95, 046804 (2005).

    Article  CAS  Google Scholar 

  18. Ploigt, H.-C., Brun, C., Pivetta, M., Patthey, F. & Schneider, W.-D. Local work function changes determined by field emission resonances: NaCl/Ag(100). Phys. Rev. B 76, 195404 (2007).

    Article  Google Scholar 

  19. Dougherty, D. B., Maksymovych, P., Lee, J. & Yates, J. T. Jr Local spectroscopy of image-potential-derived states: From single molecules to monolayers of benzene on Cu(111). Phys. Rev. Lett. 97, 236806 (2006).

    Article  CAS  Google Scholar 

  20. Zerweck, U., Loppacher, C., Otto, T., Grafström, S. & Eng, L. M. Accuracy and resolution limits of Kelvin probe force microscopy. Phys. Rev. B 71, 125424 (2005).

    Article  Google Scholar 

  21. Olesen, L. et al. Apparent barrier height in scanning tunneling microscopy revisited. Phys. Rev. Lett. 76, 1485 (1996).

    Article  CAS  Google Scholar 

  22. Sotiropoulos, A., Milligan, P. K., Cowie, B. C. C. & Kadodwala, M. A structural study of formate on Cu(111). Surf. Sci. 444, 52–60 (2000).

    Article  CAS  Google Scholar 

  23. Johnston, S. M., Rousseau, G., Dhanak, V. & Kododwala, M. The structure of acetate and trifluoroacetate on Cu(111). Surf. Sci. 477, 163–173 (2001).

    Article  CAS  Google Scholar 

  24. Lin, N. et al. Two-dimensional adatom gas bestowing dynamic heterogeneity on surfaces. Angew. Chem. Int. Ed. 44, 1488–1491 (2005).

    Article  CAS  Google Scholar 

  25. Rusu, P.C., Giovannetti, G., Weijtens, C., Coehoorn, R. & Borcks, G. Work function pinning at metal–organic interfaces. J. Phys. Chem. C 113, 9974–9977 (2009).

    Article  CAS  Google Scholar 

  26. Tait, S. L. et al. One-dimensional self-assembled molecular chains on Cu(100): Interplay between surface-assisted coordination chemistry and substrate commensurability. J. Phys. Chem. C 111, 10982–10987 (2007).

    Article  CAS  Google Scholar 

  27. Barth, J. V., Costantini, G. & Kern, K. Engineering atomic and molecular nanostructures at surfaces. Nature 437, 671–679 (2005).

    Article  CAS  Google Scholar 

  28. Gambardella, P. et al. Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface. Nature Mater. 8, 189–193 (2009).

    Article  CAS  Google Scholar 

  29. Baroni, S. et al. <http://www.quantum-espresso.org>.

  30. Bengtsson, L. Dipole correction for surface supercell calculations. Phys. Rev. B 59, 12301 (1999).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

We thank Mario Ruben for synthesizing the PVBA. A.D.V. and G.L. acknowledge funding from EPSRC grant EP/G044864/1 and the ESF-EUROCORES SONS Programme.

Author information

Authors and Affiliations

  1. Max-Planck-Institut für Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany

    Lucia Vitali, Giacomo Levita, Robin Ohmann & Klaus Kern

  2. INFM-DEMOCRITOS National Simulation Center and Center of Excellence for Nanostructured Materials (CENMAT), University of Trieste, via Valerio 6a, 34127 Trieste, Italy

    Giacomo Levita

  3. Physics Department, King’s College London, Strand, London WC2R 2LS, UK

    Alessio Comisso & Alessandro De Vita

  4. Institut de Physique de la Matière Condensée, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland

    Klaus Kern

Authors
  1. Lucia Vitali
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Giacomo Levita
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Robin Ohmann
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Alessio Comisso
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Alessandro De Vita
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Klaus Kern
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

All authors contributed extensively to the work.

Corresponding author

Correspondence to Lucia Vitali.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 533 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Vitali, L., Levita, G., Ohmann, R. et al. Portrait of the potential barrier at metal–organic nanocontacts. Nature Mater 9, 320–323 (2010). https://doi.org/10.1038/nmat2625

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat2625

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing