Influence of backbone fluorination in regioregular poly(3-alkyl-4-fluoro)thiophenes

Zhuping Fei, Pierre Boufflet, Sebastian Wood, Jessica Wade, John Moriarty, Eliot Gann, Erin L. Ratcliff, Christopher R. Mcneill, Henning Sirringhaus, Ji Seon Kim, Martin Heeney

Research output: Contribution to journalArticle

142 Scopus citations

Abstract

We report two strategies toward the synthesis of 3-alkyl-4-fluorothiophenes containing straight (hexyl and octyl) and branched (2-ethylhexyl) alkyl groups. We demonstrate that treatment of the dibrominated monomer with 1 equiv of alkyl Grignard reagent leads to the formation of a single regioisomer as a result of the pronounced directing effect of the fluorine group. Polymerization of the resulting species affords highly regioregular poly(3-alkyl-4-fluoro)thiophenes. Comparison of their properties to those of the analogous non-fluorinated polymers shows that backbone fluorination leads to an increase in the polymer ionization potential without a significant change in optical band gap. Fluorination also results in an enhanced tendency to aggregate in solution, which is ascribed to a more co-planar backbone on the basis of Raman and DFT calculations. Average charge carrier mobilities in field-effect transistors are found to increase by up to a factor of 5 for the fluorinated polymers.

Original languageEnglish (US)
Pages (from-to)6866-6879
Number of pages14
JournalJournal of the American Chemical Society
Volume137
Issue number21
DOIs
StatePublished - Jun 3 2015

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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    Fei, Z., Boufflet, P., Wood, S., Wade, J., Moriarty, J., Gann, E., Ratcliff, E. L., Mcneill, C. R., Sirringhaus, H., Kim, J. S., & Heeney, M. (2015). Influence of backbone fluorination in regioregular poly(3-alkyl-4-fluoro)thiophenes. Journal of the American Chemical Society, 137(21), 6866-6879. https://doi.org/10.1021/jacs.5b02785