Synthesis, solid‐state, and charge‐transport properties of conjugated polythiophene‐S,S‐dioxides

An alkylated semiconducting polymer comprising alternating bithiophene-(all)-S,S-dioxide and aromatic mono- thiophene units in the polymer backbone was synthesized with the intent of modifying the energy gap and lowest unoccupied molecular orbital for use as a stable n-type semiconductor. Films spun from this semiconducting polymer were character- ized utilizing X-ray scattering, near edge X-ray absorption fine structure spectroscopy, ultraviolet photoelectron spectroscopy, and thin-film field effect transistors to determine how oxidation of the thiophene ring systems impacts the structural and elec- tronic properties of the polymer. The thiophene-S,S-dioxide polymers have lower optical and electrical band gaps than cor- responding thiophene polymers. X-ray scattering results indi- cate that the polymers are well ordered with the p-p stacking distances increased by 0.4 A u relative to analogous thiophene polymers. The electrical stability of these polymers is poor in transistors with a drop in the field effect mobility by approxi- mately one order of magnitude upon addition of just 5% of the thiophene-S,S-dioxide unit in a copolymer with thiophene. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 000: 000-000, 2012