Effect of anions on bipolaron formation in ionic-liquid-gated transistors fabricated with poly(2, 5-bis(3-hexadecylthiophen-2-yl)thieno[3, 2-b]thiophene) (PBTTT-C16)

Ippei Enokida, Yukio Furukawa

Research output: Contribution to journalReview article


The type of carrier, polaron and bipolaron, generated in PBTTT-C16 ionic-liquid-gated transistors fabricated with [EMIM][TFSI] or [EMIM][FAP] was identified using Raman spectroscopy. Doping levels were obtained from electrochemical measurements. As the doping level increased, positive polarons were formed; positive bipolarons were then formed and dominant. The critical doping level of the polaron-to-bipolaron transition was 4.5 and 12mol %/π electron for [EMIM][TFSI] and [EMIM][FAP], respectively. The large anion FAP- impeded the bipolaron formation even at a high doping level.

Original languageEnglish
Pages (from-to)498-501
Number of pages4
JournalChemistry Letters
Issue number5
Publication statusPublished - 2019 Jan 1



  • Bipolaron
  • Ionic liquid
  • Polaron

ASJC Scopus subject areas

  • Chemistry(all)

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