Phys. Rev. B 72, 235302 (2005) [5 pages]

Doping-dependent charge injection and band alignment in organic field-effect transistors

Abstract

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Citing Articles (13)

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B. H. Hamadani¹, H. Ding², Y. Gao², and D. Natelson^1,3
¹Department of Physics and Astronomy, Rice University, 6100 Main Street, Houston, Texas 77005, USA
²Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
³Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, Texas 77005, USA

Received 5 August 2005; published 2 December 2005

We have studied metal/organic semiconductor charge injection in poly(3-hexylthiophene) (P3HT) field-effect transistors with Pt and Au electrodes as a function of annealing in a vacuum. At low impurity dopant densities, Au/P3HT contact resistances increase and become nonohmic. In contrast, Pt/P3HT contacts remain ohmic even at far lower doping. Ultraviolet photoemission spectroscopy (UPS) reveals that metal/P3HT band alignment shifts dramatically as samples are dedoped, leading to an increased injection barrier for holes, with a greater shift for Au/P3HT. These results demonstrate that doping can drastically alter band alignment and the charge injection process at metal/organic interfaces.

URL:

http://link.aps.org/doi/10.1103/PhysRevB.72.235302

DOI:

10.1103/PhysRevB.72.235302

PACS:

73.30.+y, 73.61.Jc, 73.61.Ph

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Phys. Rev. B 72, 235302 (2005) [5 pages]

Doping-dependent charge injection and band alignment in organic field-effect transistors