TY - JOUR
T1 - Influence of backbone fluorination in regioregular poly(3-alkyl-4-fluoro)thiophenes
AU - Fei, Zhuping
AU - Boufflet, Pierre
AU - Wood, Sebastian
AU - Wade, Jessica
AU - Moriarty, John
AU - Gann, Eliot
AU - Ratcliff, Erin L.
AU - McNeill, Christopher R.
AU - Sirringhaus, Henning
AU - Kim, Ji-Seon
AU - Heeney, Martin
PY - 2015
Y1 - 2015
N2 - 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.
AB - 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.
UR - http://pubs.acs.org.ezproxy.lib.monash.edu.au/doi/pdf/10.1021/jacs.5b02785
U2 - 10.1021/jacs.5b02785
DO - 10.1021/jacs.5b02785
M3 - Article
VL - 137
SP - 6866
EP - 6879
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 21
ER -