Skip to main content

Thank you for visiting 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.

  • Letter
  • Published:

Metallic transport in polyaniline


Despite nearly three decades of materials development, the transport properties in the ‘metallic state’ of the so-called conducting polymers are still not typical of conventional metals1,2,3,4,5,6,7. The hallmark of metallic resistivity—a monotonic decrease in resistivity with temperature—has not been obtained at temperatures over the full range below room temperature; and a frequency dependent conductivity, σ(ω), typical of metals has also not been observed. In contrast, the low-temperature behaviour of ‘metallic’ polymers has, in all previous cases, exhibited an increase in resistivity as temperature is further decreased, as a result of disorder-induced localization of the charge carriers1,2,3,4. This disorder-induced localization also changes the infrared response such that σ(ω) deviates from the prediction of Drude theory5,6,7. Here we report classic metallic transport data obtained from truly metallic polymers. With polyaniline samples prepared using self-stabilized dispersion polymerization8, we find that for samples having room-temperature conductivities in excess of 1,000 S cm-1, the resistivity decreases monotonically as the temperature is lowered down to 5 K, and that the infrared spectra are characteristic of the conventional Drude model even at the lowest frequencies measured.

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

Access options

Buy this article

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

Figure 1: Diagram of the self-stabilized dispersion polymerization of polyaniline.
Figure 2: Temperature dependence of resistivity, ρ(T).
Figure 3: Optical spectra of high-conductivity PANI-CSA.
Figure 4: X-ray diffraction patterns of the SSDP PANI-CSA samples.

Similar content being viewed by others


  1. Heeger, A. J. Nobel Lecture: Semiconducting and metallic polymers: The fourth generation of polymeric materials. Rev. Mod. Phys. 73, 681–700 (2001)

    Article  ADS  CAS  Google Scholar 

  2. Menon, R., Yoon, C. O., Moses, D. & Heeger, A. J. in Handbook of Conducting Polymers 2nd edn (eds Skotheim, T. A., Elsenbaumer, R. L. & Reynolds, J. R.) 27–84 (Marcel Dekker, New York, 1998)

    Google Scholar 

  3. Heeger, A. J. The critical regime of the metal-insulator transition in conducting polymers: experimental studies. Phys. Scr. T102, 30–35 (2002)

    Article  ADS  CAS  Google Scholar 

  4. Kaiser, A. B. Systematic conductivity behaviour in conducting polymers: effects of heterogeneous disorder. Adv. Mater. 13, 927–941 (2001)

    Article  ADS  CAS  Google Scholar 

  5. Kiebooms, R., Menon, R. & Lee, K. in Handbook of Advanced Electronic and Photonic Materials and Devices Vol. 8 (ed. Nalwa, H. S.) 1–102 (Academic, San Diego, 2001)

    Book  Google Scholar 

  6. Kohlman, R. S., Joo, J. & Epstein, A. J. in Physical Properties of Polymers Handbook (ed. Mark, J. E.) 453–478 (AIP, New York, 1996)

    Google Scholar 

  7. Lee, K. in Encyclopedia of Nanoscience and Nanotechnology Vol. 5 (ed. Nalwa, H. S.) 537–549 (American Scientific Publishers, San Diego, 2004)

    Google Scholar 

  8. Lee, S.-H., Lee, D.-H., Lee, K. & Lee, C.-W. High-performance polyaniline prepared via polymerization in a self-stabilized dispersion. Adv. Funct. Mater. 15, 1495–1500 (2005)

    Article  CAS  Google Scholar 

  9. Ashcroft, N. W. & Mermin, N. D. Solid State Physics (Saunders College, New York, 1976)

    MATH  Google Scholar 

  10. Landau, L. D. The theory of a Fermi liquid. Sov. Phys. JETP 3, 920–925 (1957)

    MathSciNet  CAS  MATH  Google Scholar 

  11. Pines, I. D. & Nozieres, P. The Theory of Quantum Liquids (Benjamin, Menlo Park, 1966)

    MATH  Google Scholar 

  12. Mott, N. F. Metal-insulator Transitions (Taylor & Francis, London, 1990)

    Book  Google Scholar 

  13. Anderson, P. W. The Fermi glass: theory and experiment. Comments Solid State Phys. 2, 193–198 (1970)

    Article  Google Scholar 

  14. Fite, C., Cao, Y. & Heeger, A. J. Magnetic susceptibility of one-dimensional metallic chains in solution. Solid State Commun. 73, 607–609 (1990)

    Article  ADS  CAS  Google Scholar 

  15. Park, Y. W., Choi, E. S. & Suh, D. S. Metallic temperature dependence of resistivity in perchlorate doped polyacetylene. Synth. Met. 96, 81–86 (1998)

    Article  CAS  Google Scholar 

  16. Moses, D., Denenstein, A., Pron, A., Heeger, A. J. & MacDiarmid, A. G. Specific heats of pure and doped polyacetylene. Solid State Commun. 36, 219–224 (1980)

    Article  ADS  CAS  Google Scholar 

  17. Reghu, M., Cao, Y., Moses, D. & Heeger, A. J. Counterion-induced processibility of polyaniline: transport at the metal-insulator boundary. Phys. Rev. B 47, 1758–1764 (1993)

    Article  ADS  CAS  Google Scholar 

  18. Yoon, C. O., Reghu, M., Moses, D. & Heeger, A. J. Transport near the metal-insulator transition: polypyrrole doped with PF6 . Phys. Rev. B 49, 10851–10863 (1994)

    Article  ADS  CAS  Google Scholar 

  19. Wang, Z. H., Scherr, E. M., MacDiarmid, A. G. & Epstein, A. J. Transport and EPR studies of polyaniline: a quasi one-dimensional conductor with three dimensional “metallic” states. Phys. Rev. B 45, 4190–4202 (1992)

    Article  ADS  CAS  Google Scholar 

  20. Lee, K., Heeger, A. J. & Cao, Y. Reflectance of polyaniline protonated with camphor sulfonic acid: disordered metal on the metal-insulator boundary. Phys. Rev. B 48, 14884–14891 (1993)

    Article  ADS  CAS  Google Scholar 

  21. Lee, K. et al. Nature of the metallic state in conducting polypyrrole. Adv. Mater. 10, 456–459 (1998)

    Article  CAS  Google Scholar 

  22. Kohlman, R. S. et al. Limit for metallic conductivity in conducting polymers. Phys. Rev. Lett. 78, 3915–3918 (1995)

    Article  ADS  Google Scholar 

  23. Chapman, B. et al. Low-energy conductivity of PF6-doped polypyrrole. Phys. Rev. B 60, 13479–13483 (1999)

    Article  ADS  CAS  Google Scholar 

  24. Tzamalis, G., Zaidi, N. A., Homes, C. C. & Monkman, A. P. Doping-dependent studies of the Anderson-Mott localization in polyaniline at the metal-insulator boundary. Phys. Rev. B 66, 085202 (2002)

    Article  ADS  Google Scholar 

  25. Lee, K. & Heeger, A. J. Optical investigation of intra and interchain charge dynamics in conducting polymers. Synth. Met. 128, 279–282 (2002)

    Article  CAS  Google Scholar 

  26. MacDiarmid, A. G. & Epstein, A. J. Secondary doping in polyaniline. Synth. Met. 69, 85–92 (1995)

    Article  CAS  Google Scholar 

  27. Yan, H., Ohta, T. & Toshima, N. Stretched polyaniline films doped by (± )-10-camphorsulfonic acid: anisotropy and improvement of thermoelectric properties. Macromol. Mater. Eng. 286, 139–142 (2001)

    Article  CAS  Google Scholar 

Download references


We thank K. Bechgaard for discussions. K.L. was supported at PNU by the National Program for Nanoscience and Technology of the Korea Science and Engineering Foundation. S.-H.L. acknowledges financial support at AU from the Korea Science and Engineering Foundation through the Hyper Structured Organic Materials Research Center in Seoul National University. Work at UCSB was supported by the National Science Foundation.

Author information

Authors and Affiliations


Corresponding authors

Correspondence to Kwanghee Lee or Suck-Hyun Lee.

Ethics declarations

Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Lee, K., Cho, S., Heum Park, S. et al. Metallic transport in polyaniline. Nature 441, 65–68 (2006).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


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