Molecular basis of mesophase ordering in a thiophene-based copolymer

Dean M. Delongchamp, R. Joseph Kline, Youngsuk Jung, Eric K. Lin, Daniel A. Fischer, David J. Gundlach, Sarah K. Cotts, Andrew J. Moad, Lee J. Richter, Michael F. Toney, Martin Heeney, Iain Mcculloch

Research output: Contribution to journalArticlepeer-review

88 Scopus citations

Abstract

The carrier mobility of poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b] thiophene) semiconductors can be substantially enhanced after heating through a thermotropic mesophase transition, which causes a significant improvement in thin film structural order. By directly measuring film structure throughout a heating and cooling cycle, we identify the molecular origin of this mesophase transition as the melting of interdigitated linear alkane side chains, in this case quaterdecyl. The morphology and phase behavior throughout the thermal cycle are controlled by the changing conformation of the side chains. Surprisingly, the melting of the side chains allows increases in the backbone order, π-π stacking, and carrier mobility. Upon cooling, the side chains recrystallize to preserve the excellent mesophase order and enhanced electrical performance.

Original languageEnglish (US)
Pages (from-to)5709-5715
Number of pages7
JournalMacromolecules
Volume41
Issue number15
DOIs
StatePublished - Aug 12 2008

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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