Thin-film morphology of inkjet-printed single-droplet organic transistors using polarized Raman spectroscopy: Effect of blending TIPS-pentacene with insulating polymer

David T. James, B.K. Charlotte Kjellander, Wiljan T.T. Smaal, Gerwin H. Gelinck, Craig Combe, Iain McCulloch, Richard Wilson, Jeremy H. Burroughes, Donal D.C. Bradley, Ji Seon Kim

Research output: Contribution to journalArticleAcademicpeer-review

91 Citations (Scopus)

Abstract

We report thin-film morphology studies of inkjet-printed single-droplet organic thin-film transistors (OTFTs) using angle-dependent polarized Raman spectroscopy. We show this to be an effective technique to determine the degree of molecular order as well as to spatially resolve the orientation of the conjugated backbones of the 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pentacene) molecules. The addition of an insulating polymer, polystyrene (PS), does not disrupt the π-π stacking of the TIPS-Pentacene molecules. Blending in fact improves the uniformity of the molecular morphology and the active layer coverage within the device and reduces the variation in molecular orientation between polycrystalline domains. For OTFT performance, blending enhances the saturation mobility from 0.22 ± 0.05 cm 2/ (V·s) (TIPS-Pentacene) to 0.72 ± 0.17 cm 2/(V·s) (TIPS-Pentacene:PS) in addition to improving the quality of the interface between TIPS-Pentacene and the gate dielectric in the channel, resulting in threshold voltages of ∼0 V and steep subthreshold slopes.

Original languageEnglish
Pages (from-to)9824-9835
Number of pages12
JournalACS Nano
Volume5
Issue number12
DOIs
Publication statusPublished - 27 Dec 2011
Externally publishedYes

Keywords

  • inkjet printing
  • morphology
  • organic transistors
  • pentacene
  • Raman spectroscopy

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