Hopping and trapping mechanisms in organic field-effect transistors

S. J. Konezny, M. N. Bussac, and L. Zuppiroli
Phys. Rev. B 81, 045313 – Published 15 January 2010

Abstract

A charge carrier in the channel of an organic field-effect transistor (OFET) is coupled to the electric polarization of the gate in the form of a surface Fröhlich polaron [N. Kirova and M. N. Bussac, Phys. Rev. B 68, 235312 (2003)]. We study the effects of the dynamical field of polarization on both small-polaron hopping and trap-limited transport mechanisms. We present numerical calculations of polarization energies, band-narrowing effects due to polarization, hopping barriers, and interface trap depths in pentacene and rubrene transistors as functions of the dielectric constant of the gate insulator and demonstrate that a trap-and-release mechanism more appropriately describes transport in high-mobility OFETs. For mobilities on the order 0.1cm2/Vs and below, all states are highly localized and hopping becomes the predominant mechanism.

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  • Received 28 April 2009

DOI:https://doi.org/10.1103/PhysRevB.81.045313

©2010 American Physical Society

Authors & Affiliations

S. J. Konezny*, M. N. Bussac, and L. Zuppiroli

  • Laboratoire d’Optoélectronique des Matériaux Moléculaires, STI-IMX-LOMM, Station 3, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

  • *Present address: Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT 06520-8107, USA; sjkonezny@gmail.com
  • Permanent address: Centre de Physique Théorique, UMR-7644 du Centre National de la Recherche Scientifique, École Polytechnique, F-91128 Palaiseau Cedex, France.

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Vol. 81, Iss. 4 — 15 January 2010

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