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.

  • Article
  • Published:

Site- and orbital-dependent charge donation and spin manipulation in electron-doped metal phthalocyanines

Nature Materials volume 12, pages 337–343 (2013)Cite this article

Subjects

This article has been updated

Abstract

Chemical doping offers promise as a means of tailoring the electrical characteristics of organic molecular compounds. However, unlike for inorganic semiconductors used in electronics applications, controlling the influence of dopants in molecular complexes is complicated by the presence of multiple doping sites, electron acceptor levels, and intramolecular correlation effects. Here we use scanning tunnelling microscopy to analyse the position of individual Li dopants within Cu- and Ni-phthalocyanine molecules in contact with a metal substrate, and probe the charge transfer process with unprecedented spatial resolution. We show that individual phthalocyanine molecules can host at least three distinct stable doping sites and up to six dopant atoms, and that the ligand and metal orbitals can be selectively charged by modifying the configuration of the Li complexes. Li manipulation reveals that charge transfer is determined solely by dopants embedded in the molecules, whereas the magnitude of the conductance gap is sensitive to the molecule–dopant separation. As a result of the strong spin–charge correlation in confined molecular orbitals, alkali atoms provide an effective way for tuning the molecular spin without resorting to magnetic dopants.

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

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

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

Figure 1: Formation of LixCuPc complexes.
Figure 2: Calculated electronic structure of LixMPc complexes.
Figure 3: Selective orbital doping of CuPc.
Figure 4: Doping of NiPc.
Figure 5: Atom-by-atom doping of CuPc.
Figure 6: Long-range interactions between dopants and molecules.

Similar content being viewed by others

Change history

  • 11 March 2013

    In the version of this Article originally published online, at the start of the second paragraph of the section 'Doping limit of single MPc', the sentence describing a figure that "shows the dI/dV spectra as a function of the number of Li atoms" should have referred to Figure 5b rather than 4b. This error has been corrected in all versions of the Article.

References

  1. Walzer, K., Maennig, B., Pfeiffer, M. & Leo, K. Highly efficient organic devices based on electrically doped transport layers. Chem. Rev. 107, 1233–1271 (2007).

    Article  CAS  Google Scholar 

  2. Tosatti, E., Fabrizio, M., Tóbik, J. & Santoro, G. Strong correlations in electron doped phthalocyanine conductors near half filling. Phys. Rev. Lett. 93, 117002 (2004).

    Article  Google Scholar 

  3. Hebard, A. F. et al. Superconductivity at 18 K in potassium-doped C60. Nature 350, 600–601 (1991).

    Article  CAS  Google Scholar 

  4. Mitsuhashi, R. et al. Superconductivity in alkali-metal-doped picene. Nature 464, 76–79 (2010).

    Article  CAS  Google Scholar 

  5. Takenobu, T., Muro, T., Iwasa, Y. & Mitani, T. Antiferromagnetism and phase diagram in ammoniated alkali fulleride salts. Phys. Rev. Lett. 85, 381–384 (2000).

    Article  CAS  Google Scholar 

  6. Haddon, R. C. et al. Conducting films of C60 and C70 by alkali-metal doping. Nature 350, 320–322 (1991).

    Article  CAS  Google Scholar 

  7. Parthasarathy, G., Shen, C., Kahn, A. & Forrest, S. R. Lithium doping of semiconducting organic charge transport materials. J. Appl. Phys. 89, 4986–4992 (2001).

    Article  CAS  Google Scholar 

  8. Minakata, T., Ozaki, M. & Imai, H. Conducting thin films of pentacene doped with alkaline metals. J. Appl. Phys. 74, 1079–1082 (1993).

    Article  CAS  Google Scholar 

  9. Kido, J. & Matsumoto, T. Bright organic electroluminescent devices having a metal-doped electron-injecting layer. Appl. Phys. Lett. 73, 2866–2868 (1998).

    Article  CAS  Google Scholar 

  10. Hung, L. S. & Tang, C. W. Interface engineering in preparation of organic surface-emitting diodes. Appl. Phys. Lett. 74, 3209–3211 (1999).

    Article  CAS  Google Scholar 

  11. Schwieger, T., Peisert, H., Golden, M., Knupfer, M. & Fink, J. Electronic structure of the organic semiconductor copper phthalocyanine and K-CuPc studied using photoemission spectroscopy. Phys. Rev. B 66, 155207 (2002).

    Article  Google Scholar 

  12. Flatz, K., Grobosch, M. & Knupfer, M. The electronic properties of potassium doped copper-phthalocyanine studied by electron energy-loss spectroscopy. J. Chem. Phys. 126, 214702 (2007).

    Article  CAS  Google Scholar 

  13. Giovanelli, L. et al. Phase separation in potassium-doped ZnPc thin films. J. Chem. Phys. 126, 044709 (2007).

    Article  CAS  Google Scholar 

  14. Evangelista, F. et al. Electronic properties and orbital-filling mechanism in Rb-intercalated copper phthalocyanine. J. Phys. Chem. C 112, 6509–6514 (2008).

    Article  CAS  Google Scholar 

  15. Ding, H., Park, K., Green, K. & Gao, Y. Electronic structure modification of copper phthalocyanine (CuPc) induced by intensive Na doping. Chem. Phys. Lett. 454, 229–232 (2008).

    Article  CAS  Google Scholar 

  16. König, A., Roth, F., Kraus, R. & Knupfer, M. Electronic properties of potassium doped FePc from electron energy-loss spectroscopy. J. Chem. Phys. 130, 214503 (2009).

    Article  Google Scholar 

  17. Gargiani, P., Calabrese, A., Mariani, C. & Betti, M. G. Control of electron injection barrier by electron doping of metal phthalocyanines. J. Phys. Chem. C 114, 12258–12264 (2010).

    Article  CAS  Google Scholar 

  18. Yan, L., Watkins, N. J., Zorba, S., Gao, Y. & Tang, C. W. Direct observation of Fermi-level pinning in Cs-doped CuPc film. Appl. Phys. Lett. 79, 4148–4150 (2001).

    Article  CAS  Google Scholar 

  19. Craciun, M. F. et al. Electronic transport through electron-doped metal phthalocyanine materials. Adv. Mater. 18, 320–324 (2006).

    Article  CAS  Google Scholar 

  20. Craciun, M. F., Rogge, S. & Morpurgo, A. F. Correlation between molecular orbitals and doping dependence of the electrical conductivity in electron-doped metal-phthalocyanine compounds. J. Am. Chem. Soc. 127, 12210–12211 (2005).

    Article  CAS  Google Scholar 

  21. Giovannetti, G., Brocks, G. & van den Brink, J. Ab initio electronic structure and correlations in pristine and potassium-doped molecular crystals of copper phthalocyanine. Phys. Rev. B 77, 035133 (2008).

    Article  Google Scholar 

  22. Filibian, M. et al. Strong electronic correlations in LixZnPc organic metals. Phys. Rev. Lett. 100, 117601 (2008).

    Article  CAS  Google Scholar 

  23. Bao, Z., Lovinger, A. J. & Dodabalapur, A. Organic field-effect transistors with high mobility based on copper phthalocyanine. Appl. Phys. Lett. 69, 3066–3068 (1996).

    Article  CAS  Google Scholar 

  24. Boer, R. W. I. de et al. Ambipolar Cu- and Fe-phthalocyanine single-crystal field-effect transistors. Appl. Phys. Lett. 86, 262109 (2005).

    Article  Google Scholar 

  25. Parthasarathy, G., Burrows, P. E., Khalfin, V., Kozlov, V. G. & Forrest, S. R. A metal-free cathode for organic semiconductor devices. Appl. Phys. Lett. 72, 2138–2140 (1998).

    Article  CAS  Google Scholar 

  26. Singh, V. P. et al. Copper-phthalocyanine-based organic solar cells with high open-circuit voltage. Appl. Phys. Lett. 86, 082106 (2005).

    Article  Google Scholar 

  27. Cinchetti, M. et al. Tailoring the spin functionality of a hybrid metal-organic interface by means of alkali-metal doping. Phys. Rev. Lett. 104, 217602 (2010).

    Article  Google Scholar 

  28. Lodi Rizzini, A. et al. Coupling single molecule magnets to ferromagnetic substrates. Phys. Rev. Lett. 107, 177205 (2011).

    Article  CAS  Google Scholar 

  29. Mugarza, A. et al. Orbital specific chirality and homochiral self-assembly of achiral molecules induced by charge transfer and spontaneous symmetry breaking. Phys. Rev. Lett. 105, 115702 (2010).

    Article  CAS  Google Scholar 

  30. Mugarza, A. et al. Electronic and magnetic properties of molecule-metal interfaces: Transition-metal phthalocyanines adsorbed on Ag(100). Phys. Rev. B 85, 155437 (2012).

    Article  Google Scholar 

  31. Mugarza, A. et al. Spin coupling and relaxation inside molecule–metal contacts. Nature Commun. 2, 490 (2011).

    Article  Google Scholar 

  32. Stepanow, S. et al. Giant spin and orbital moment anisotropies of a Cu-phthalocyanine monolayer. Phys. Rev. B 82, 014405 (2010).

    Article  Google Scholar 

  33. Qiu, X. H., Nazin, G. V. & Ho, W. Vibronic states in single molecule electron transport. Phys. Rev. Lett. 92, 206102 (2004).

    Article  CAS  Google Scholar 

  34. Cohen, A. J., Mori-Sánchez, P. & Yang, W. Insights into current limitations of density functional theory. Science 321, 792–794 (2008).

    Article  CAS  Google Scholar 

  35. Yamachika, R. Controlled atomic doping of a single C60 mlecule. Science 304, 281–284 (2004).

    Article  CAS  Google Scholar 

  36. Roth, F., König, A., Kraus, R. & Knupfer, M. Potassium induced phase transition of FePc thin films. J. Chem. Phys. 128, 194711 (2008).

    Article  CAS  Google Scholar 

  37. Simic-Milosevic, V. et al. Substrate-mediated interaction and electron-induced diffusion of single lithium atoms on Ag(001). Phys. Rev. B 75, 195416 (2007).

    Article  Google Scholar 

  38. Song, C-L. et al. Charge-transfer-induced cesium superlattices on graphene. Phys. Rev. Lett. 108, 156803 (2012).

    Article  Google Scholar 

  39. Muiño, R. D., Sánchez-Portal, D., Silkin, V. M., Chulkov, E. V. & Echenique, P. M. Time-dependent electron phenomena at surfaces. Proc. Natl Acad. Sci. USA 108, 971–976 (2011).

    Article  Google Scholar 

  40. Sanvito, S. Molecular spintronics. Chem. Soc. Rev. 40, 3336 (2011).

    Article  CAS  Google Scholar 

  41. Koenraad, P. M. & Flatté, M. E. Single dopants in semiconductors. Nature Mater. 10, 91–100 (2011).

    Article  CAS  Google Scholar 

  42. Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999).

    Article  CAS  Google Scholar 

  43. Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comp. Mater. Sci. 6, 15–50 (1996).

    Article  CAS  Google Scholar 

  44. Tang, W., Sanville, E. & Henkelman, G. A grid-based Bader analysis algorithm without lattice bias. J. Phys. Condens. Matter 21, 084204 (2009).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

We thank N. Lorente and D. Sánchez-Portal for useful discussions. This work was supported by the European Research Council (StG 203239 NOMAD), Ministerio de Economı´a y Competitividad (MAT2010-15659), and Agència de Gestió d’Ajuts Universitaris i de Recerca (2009 SGR 695). A.M. acknlowledges the Spanish Ministerio de Ciencia e Innovación for a Ramon y Cajal Fellowship.

Author information

Authors and Affiliations

  1. Catalan Institute of Nanotechnology (ICN), UAB Campus, E-08193 Barcelona, Spain

    Cornelius Krull, Aitor Mugarza & Pietro Gambardella

  2. Centre d’Investigacions en Nanociència i Nanotecnologia CIN2 (ICN-CSIC), UAB Campus, E-08193 Barcelona, Spain

    Roberto Robles

  3. Institució Catalana de Recerca i Estudis Avançats (ICREA) and Departament de Fı´sica, Universitat Autonoma de Barcelona, E-08193 Barcelona, Spain

    Pietro Gambardella

Authors
  1. Cornelius Krull
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Roberto Robles
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Aitor Mugarza
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Pietro Gambardella
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

C.K., A.M. and P.G. planned the experiment; C.K. and A.M. performed the measurements; C.K., A.M. and P.G. analysed the data and wrote the manuscript. R.R. performed the DFT calculations. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Aitor Mugarza.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1208 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Krull, C., Robles, R., Mugarza, A. et al. Site- and orbital-dependent charge donation and spin manipulation in electron-doped metal phthalocyanines. Nature Mater 12, 337–343 (2013). https://doi.org/10.1038/nmat3547

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat3547

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