Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers

Jui Fen Chang, Jenny Clark, Ni Zhao, Henning Sirringhaus*, Dag W. Breiby, Jens W. Andreasen, Martin M. Nielsen, Mark Giles, Martin Heeney, Iain Mcculloch

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

261 Scopus citations

Abstract

Interchain interactions have a profound effect on the optical as well as charge transport properties of conjugated polymer thin films. In contrast to oligomeric model systems in solution-deposited polymer thin films the study of such effects is complicated by the complex microstructure. We present here a detailed study of interchain interaction effects on both charged polarons as well as neutral excitons in highly crystalline, high-mobility poly-3-hexylthiophene (P3HT) as a function of molecular weight. We find experimental evidence for reduced exciton bandwidth and increased polaron delocalization with increasing conjugation length and crystalline quality. From comparative studies of field-effect transistor characteristics, film morphology, and optical properties our study provides a microscopic understanding of the factors which limit the charge transport in P3HT to field-effect mobilities around 0.1 cm2 V s, and which will need to be addressed to improve mobility further.

Original languageEnglish (US)
Article number115318
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume74
Issue number11
DOIs
StatePublished - Oct 2 2006

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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