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

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

Research output: Contribution to journalArticlepeer-review

37 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 (US)
Pages (from-to)1800723
JournalAdvanced Electronic Materials
Issue number5
StatePublished - Mar 14 2019

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: T.D.A. and A.F.P. acknowledge financial support from King Abdullah University of Science and Technology (KAUST).


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