High anisotropy of the field-effect transistor mobility in magnetically aligned discotic liquid-crystalline semiconductors

I.O. Shklyarevskiy, P. Jonkheijm, N. Stutzmann, D. Wasserberg, H.J. Wondergem, P.C.M. Christianen, A.P.H.J. Schenning, D.M. Leeuw, de, Z. Tomovic, J. Wu, K. Müllen, J.C. Maan

Research output: Contribution to journalArticleAcademicpeer-review

174 Citations (Scopus)

Abstract

A magnetic field has been utilized for producing highly oriented films of a substituted hexabenzocoronene (HBC). Optical microscopy studies revealed large area HBC monodomains that covered the entire film, while wide-angle X-ray measurements showed that the HBC molecules are aligned with their planes along the applied field. On the basis of this method, solution-processed field-effect transistors (FET) have been constructed with charge carrier mobilities of up to 10-3 cm2/V·s, which are significantly enhanced with respect to the unaligned material. Exceptionally high mobility anisotropies of 25-75 for current flow parallel and perpendicular to the alignment direction have been measured as a function of the channel length. Atomic force microscopy performed on the FET structures reveals fibril superstructures that are oriented perpendicularly to the magnetic field direction, consisting of molecular columns with a slippage angle of 40° between the molecules. For channel lengths larger than 2.5 µm, the fibrils are smaller than the electrode spacing, which adversely affects the device performance.
Original languageEnglish
Pages (from-to)16233-16237
JournalJournal of the American Chemical Society
Volume127
Issue number46
DOIs
Publication statusPublished - 2005

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