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

B. H. Hamadani·H. Ding·Y. Hao·D. Natelson
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Abstract

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 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.

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B. H. Hamadani, H. Ding, Y. Hao, D. Natelson. 2005-12-14. Doping dependent charge injection and band alignment in organic field-effect transistors. https://doi.org/10.1103/physrevb.72.235302

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