Highly conducting polyparaphenylene, polypyrrole, and polythiophene chains: An ab initio study of the geometry and electronic-structure modifications upon doping

Jean-Luc Bredas*, B. Thémans, J. G. Fripiat, J. M. André, R. R. Chance

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

635 Scopus citations

Abstract

The effect of charge-transfer doping on the geometric and electronic structures of conjugated polymers has been investigated at the ab initio level with explicit consideration of the doping agents. Three systems were chosen for study as prototypical examples of conjugated polymers with nondegenerate ground states: polyparaphenylene, polypyrrole, and polythiophene. As a result of charge transfer with electron-donating dopants, extra charges appear on the polymer chains and induce strong geometry modifications. The lattice evolves from an aromatic structure towards a quinoid-like structure. Charged defects associated with lattice deformations such as spinless bipolarons are formed. The influence on the electronic structure of the polymer chains is such that with respect to the undoped case, new states appear within the gap. For the maximum doping levels experimentally achieved, band-structure calculations demonstrate that the states in the gap overlap to form bipolaron bands, a few tenths of an electron volt wide. The presence of these bipolaron bands is consistent with optical data as well as with magnetic data which suggest that the charge carriers in the highly conducting regime are spinless.

Original languageEnglish (US)
Pages (from-to)6761-6773
Number of pages13
JournalPhysical Review B
Volume29
Issue number12
DOIs
StatePublished - Jan 1 1984

ASJC Scopus subject areas

  • Condensed Matter Physics

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