Bis(thienothiophenyl) diketopyrrolopyrrole-based conjugated polymers with various branched alkyl side chains and their applications in thin-film transistors and polymer solar cells

Jicheol Shin, Gi Eun Park, Dae Hee Lee, Hyun Ah Um, Tae Wan Lee, Min Ju Cho, Dong Hoon Choi

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37 Citations (Scopus)


New thienothiophene-flanked diketopyrrolopyrrole and thiophene-containing π-extended conjugated polymers with various branched alkyl side-chains were successfully synthesized. 2-Octyldodecyl, 2-decyltetradecyl, 2-tetradecylhexadecyl, 2-hexadecyloctadecyl, and 2-octadecyldocosyl groups were selected as the side-chain moieties and were anchored to the N-positions of the thienothiophene-flanked diketopyrrolopyrrole unit. All five polymers were found to be soluble owing to the bulkiness of the side chains. The thin-film transistor based on the 2-tetradecylhexadecyl-substituted polymer showed the highest hole mobility of 1.92 cm2 V-1 s-1 due to it having the smallest π-π stacking distance between the polymer chains, which was determined by grazing incidence X-ray diffraction. Bulk heterojunction polymer solar cells incorporating [6,6]-phenyl-C71-butyric acid methyl ester as the n-type molecule and the additive 1,8-diiodooctane (1 vol %) were also constructed from the synthesized polymers without thermal annealing; the device containing the 2-octyldodecyl-substituted polymer exhibited the highest power conversion efficiency of 5.8%. Although all the polymers showed similar physical properties, their device performance was clearly influenced by the sizes of the branched alkyl side-chain groups.

Original languageEnglish
Pages (from-to)3280-3288
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number5
Publication statusPublished - 2015 Feb 11



  • branched alkyl side chain
  • diketopyrrolopyrrole
  • polymer semiconductor
  • polymer solar cell
  • thin-film transistor

ASJC Scopus subject areas

  • Materials Science(all)

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