Metallic state of conducting polymers: Microwave dielectric response and optical conductivity

A. J. Epstein, J. Joo, R. S. Kohlman, A. G. Macdiarmid, J. M. Weisinger, Y. Min, J. P. Pouget, J. Tsukamoto

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)


Recent advances in processing of polyaniline and polyacetylene have resulted in a new generation of conducting polymers with higher dc conductivities. We present the temperature (T) dependent microwave frequency dielectric constant, dc conductivity, and Kramers-Kronig analysis of conducting polyaniline and polyacetylene. The low temperature dielectric constant, ε, increases with the square of the x-ray crystalline domain length for preparations of HCl protonated polyaniline. For the highest crystalline polyaniline samples, ε increases dramatically with increasing T, supporting formation of three-dimensional (3-D) coupled `mesoscopic' metallic regions. A `metallic' negative ε is observed for d,1-camphor sulfonic acid doped polyaniline prepared in m-cresol. Optical studies show a linear increase in reflectivity below 7000 cm-1. Below 600 cm-1 the reflectance increases rapidly. Kramers-Kronig analysis of the ir-visible results are presented. Highly conducting polyaniline is shown to have two plasma frequencies, one at approximately 1.1 eV involving all the conduction band electrons, and one at approximately 0.015 eV (120 cm-1) that is suggested to arise from the most delocalized electrons. The concept of inhomogeneous disorder is introduced. The results for polyaniline are compared to those of highly doped polyacetylene which also show metallic negative ε demonstrating the intrinsic metallic nature of the new generation of conducting polymers.

Original languageEnglish
Title of host publicationElectrical, Optical, and Magnetic Properties of Organic Solid State Materials
EditorsAnthony F. Garito, Alex K-Y. Jen, Charles Y-C. Lee, Larry R. Dalton
PublisherPubl by Materials Research Society
Number of pages12
ISBN (Print)1558992278
Publication statusPublished - 1994
Externally publishedYes
EventProceedings of the MRS 1993 Fall Meeting - Boston, MA, USA
Duration: 1993 Nov 291993 Dec 3

Publication series

NameMaterials Research Society Symposium Proceedings
ISSN (Print)0272-9172


OtherProceedings of the MRS 1993 Fall Meeting
CityBoston, MA, USA

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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