Impact of 2-Ethylhexyl Stereoisomers on the Electrical Performance of Single-Crystal Field-Effect Transistors

Tao He, Pawaret Leowanawat, Christian Burschka, Vladimir Stepanenko, Matthias Stolte, Frank Würthner

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Many organic semiconductors (OSCs) inherit chiral alkyl chains, which ensure the desirable high solubility for solution-processing but may also lead to disorder, inhomogeneous film-formation, as well as interfacial defects due to the presence of mixtures of stereoisomers or diastereomers, which impair their peak performance. Here, single-crystal field-effect transistors (SCFETs) of a diketopyrrolopyrrole-based organic semiconductor with chiral 2-ethylhexyl substituents by sublimation in air and organic ribbon mask method are fabricated. Devices of the mesomer (R/S), both enantiomers (R/R, S/S), as well as mixtures of these three stereoisomers measured under ambient conditions exhibit all appreciable p-channel charge carrier mobilities of > 0.1 cm2 V−1 s−1 despite different packing arrangement in the R/S, R/R (or S/S), and racemate crystal structures. These results suggest a surprising tolerance for isomeric impurities. The highest literature-reported p-channel mobility so far for a diketopyrrolopyrrole-based OSC of 3.4 cm2 V−1 s−1 (Ion/Ioff of 1 × 106) is, however, only obtained for the pure R/S mesomer, illustrating the inherent potential of stereochemical purity. These results on SCFETs are further substantiated by studies on organic thin-film transistors (OTFTs) of pure and mixed thin films of the different stereoisomers.

Original languageEnglish (US)
Article number1804032
JournalAdvanced Materials
Volume30
Issue number44
DOIs
StatePublished - Nov 2 2018

Bibliographical note

Funding Information:
The authors are grateful to the Alexander-von-Humboldt Foundation for a postdoctoral fellowship for P.L. The authors thank Dr. Hagen Klauk and Dr. Ute Zschieschang (MPI für Festkörperforschung, Stuttgart) for providing us with FOPA-modified substrates and Ana-Maria Krause for the DSC measurements.

Publisher Copyright:
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Keywords

  • chirality
  • diketopyrrolopyrroles
  • organic electronics
  • single-crystal field-effect transistors

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