Impact of the Gate Dielectric on Contact Resistance in High-Mobility Organic Transistors

Alexandra F. Paterson, Alexander D. Mottram, Hendrik Faber, Muhammad R. Niazi, Zhuping Fei, Martin Heeney, Thomas D. Anthopoulos

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


The impact of the gate dielectric on contact resistance in organic thin-film transistors (OTFTs) is investigated using electrical characterization, bias-stress stability measurements, and bandgap density of states (DOS) analysis. Two similar dielectric materials, namely Cytop and poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene] (Teflon AF2400), are tested in top-gate bottom-contact OTFTs. The contact resistance of Cytop-based OTFTs is found to be greater than that of the AF2400-based devices, even though the metal/OSC interface remains identical in both systems. The Cytop devices are also found to perform worse in bias-stress stability tests which, along with the DOS calculations, suggests that charge trapping at the OSC/dielectric interface is more prevalent with Cytop than AF2400. This increased charge trapping at the Cytop OSC/dielectric interface appears to be associated with the higher contact resistance in Cytop OTFTs. Differences in the molecular structure between Cytop and AF2400 and the large difference in the glass transition temperature of the two polymers may be responsible for the observed difference in the transistor performance. Overall, this study highlights the importance of the gate dielectric material in the quest for better performing OTFTs and integrated circuits.

Original languageEnglish
Article number1800723
JournalAdvanced Electronic Materials
Issue number5
StatePublished - May 2019

Bibliographical note

Publisher Copyright:
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


  • contact resistance
  • dielectric
  • mobility overestimation
  • organic thin-film transistors
  • small molecule polymer blends

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials


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