Influence of Backbone Fluorination in Regioregular Poly(3-alkyl-4-fluoro)thiophenes
Ratcliff, Erin L.
McNeill, Christopher R.
KAUST Grant NumberCRG-1-2012-THO-015
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Abstract© 2015 American Chemical Society. 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.
CitationFei Z, Boufflet P, Wood S, Wade J, Moriarty J, et al. (2015) Influence of Backbone Fluorination in Regioregular Poly(3-alkyl-4-fluoro)thiophenes. Journal of the American Chemical Society 137: 6866–6879. Available: http://dx.doi.org/10.1021/jacs.5b02785.
SponsorsThis work was supported by EPSRC grants EP/G060738/1 and EP/K029843/1, a KAUST Competitive Research grant under agreement no. CRG-1-2012-THO-015, and the Australian Research Council (FT100100275, DP130102616). We thank Dr. Scott E. Watkins (CSIRO Melbourne) for the PESA measurements. Part of this research was undertaken on the SAXS/WAXS beamline at the Australian Synchrotron, Victoria, Australia.
PublisherAmerican Chemical Society (ACS)
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