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The influence of mechanical rubbing on the field-effect mobility in polyhexylthiophene

Heil, Holger and Finnberg, Torsten and Malm, Norwin von and Schmechel, Roland and Seggern, Heinz von (2003):
The influence of mechanical rubbing on the field-effect mobility in polyhexylthiophene.
93, In: Journal of Applied Physics, (3), pp. 1636-1641. American Institute of Physics Publishing, ISSN 00218979,
[Article]

Abstract

This paper reports on improvements of the field-effect mobility in regioregular head-to-tail coupled poly(3-hexylthiophene) based transistors by mechanically induced alignment of polymer chains in the active layer. It is demonstrated that mechanical rubbing perpendicular to the source drain contacts can increase the field-effect mobility up to 800% whereas rubbing parallel to the source drain contacts results in a reduced mobility. The polymer alignment is thereby deduced from optically polarized transmission spectroscopy on polymer-coated quartz glass substrates and is shown to directly correlate with the electrical behavior of a bottom-gate field-effect transistor. The influence of layer thickness on rubbing is investigated and it is shown that annealing after mechanical rubbing at high temperature can further increase the alignment. Differences between thick drop-cast and thin spin-coated films are explained in terms of different solvent evaporation rates, allowing the material to order to a different degree. This interpretation is deduced from characteristic optical and electrical features of the differently prepared poly(3-hexylthiophene) films.

Item Type: Article
Erschienen: 2003
Creators: Heil, Holger and Finnberg, Torsten and Malm, Norwin von and Schmechel, Roland and Seggern, Heinz von
Title: The influence of mechanical rubbing on the field-effect mobility in polyhexylthiophene
Language: English
Abstract:

This paper reports on improvements of the field-effect mobility in regioregular head-to-tail coupled poly(3-hexylthiophene) based transistors by mechanically induced alignment of polymer chains in the active layer. It is demonstrated that mechanical rubbing perpendicular to the source drain contacts can increase the field-effect mobility up to 800% whereas rubbing parallel to the source drain contacts results in a reduced mobility. The polymer alignment is thereby deduced from optically polarized transmission spectroscopy on polymer-coated quartz glass substrates and is shown to directly correlate with the electrical behavior of a bottom-gate field-effect transistor. The influence of layer thickness on rubbing is investigated and it is shown that annealing after mechanical rubbing at high temperature can further increase the alignment. Differences between thick drop-cast and thin spin-coated films are explained in terms of different solvent evaporation rates, allowing the material to order to a different degree. This interpretation is deduced from characteristic optical and electrical features of the differently prepared poly(3-hexylthiophene) films.

Journal or Publication Title: Journal of Applied Physics
Volume: 93
Number: 3
Publisher: American Institute of Physics Publishing
Uncontrolled Keywords: polymer films, insulated gate field effect transistors, molecular orientation, organic semiconductors, electron mobility, molecular electronics, spin coating, visible spectra, photoluminescence, annealing, casting
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Electronic Materials
Date Deposited: 19 Jun 2013 08:13
Official URL: http://dx.doi.org/10.1063/1.1530720
Identification Number: doi:10.1063/1.1530720
Funders: The authors would like to thank the BMBF and Siemens AG for financial support., The spectral ellipsometer is an item on loan from the DFG.
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