Correlating molecular design to microstructure in thermally convertible oligothiophenes: The effect of branched versus linear end groups

Dean M. DeLongchamp*, Youngsuk Jung, Daniel A. Fischer, Eric K. Lin, Paul Chang, Vivek Subramanian, Amanda R. Murphy, Jean Frechet

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

The thin film microstructure development of functionalized oligothiophenes with branched, thermally removable groups at each end of conjugated cores with five, six, and seven thiophene rings was monitored during their thermal conversion from solution processible precursors to insoluble semiconductor products. The change in end group character provides a comparison of branched vs linear end group functionalization in oligothiophenes. Near edge X-ray absorption fine structure (NEXAFS) spectroscopy confirmed that branched α-, ω-substitutions of the precursors strongly influenced the packing of the conjugated core. The quinque- and sexithiophene precursors oriented perpendicular to the substrate, whereas the septithiophene precursor oriented parallel to the substrate, providing one of the first examples of length dependence in oligothiophene orientation. This dependence may be due to a packing mismatch between the conjugated cores and the branched end groups. The convertible septithiophene exhibits four distinct microstructures as it converts from precursor to product that correlate strongly with its field-effect hole mobility in field-effect transistors. The extent of septithiophene order and the surface-relative orientation of its ordered phases clearly influence field-effect transistor performance.

Original languageEnglish (US)
Pages (from-to)10645-10650
Number of pages6
JournalJournal of Physical Chemistry B
Volume110
Issue number22
DOIs
StatePublished - Jun 8 2006

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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