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Proceedings Paper

Vibration-induced mobility enhancement for a polymer transistor
Author(s): Yuuki Kondo; Tomonori Hiraki; Yuusuke Suenaga; Tomonori Hanasaki; Ichiro Fujieda
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Paper Abstract

Charge transport in an organic thin-film transistor (OTFT) is controlled by many factors such as molecular packing in the semiconductor material and the contact property at the source/drain electrode. One approach utilizes an alignment layer to influence the molecular packing. Charge transport becomes anisotropic. However, additional processes are required to form such a structured layer. Solution processes offer more pathways in influencing the molecular packing. These include the use of solvent mixtures for adjusting the evaporation-induced flows, the temperature gradient in molten materials, drop-casting on tilted substrates, and other flow-induced processes. Common to these approaches is the fact that some forms of forces introduce directionality in semiconductor materials. Here, we propose to agitate organic molecules in a solution by applying ultrasound vibrations during the solvent evaporation. The vibration would translate and rotate the molecules and this might introduce ordering in the organic layer when the solvent evaporation is completed. In experiment, we fabricated bottom-contact polymer transistors by dispensing a poly(3- hexylthiophene)/1,2,4-trichlorobenzene solution on a substrate and subsequently drying it in a container immersed in an ultrasound bath. The average field effect mobility of the transistors prepared from a 0.1wt% solution with 30-min ultrasound vibration was 2.5 times higher than that of the control devices prepared without the vibration. We attribute this result to enhanced ordering of the P3HT molecules in the vibrated solution. Atomic-force microscope observation revealed longer polymer chains for the samples prepared with the vibration. We attribute this mobility enhancement to changes in molecular packing during the solvent evaporation.

Paper Details

Date Published: 20 February 2012
PDF: 6 pages
Proc. SPIE 8258, Organic Photonic Materials and Devices XIV, 82581A (20 February 2012); doi: 10.1117/12.906567
Show Author Affiliations
Yuuki Kondo, Ritsumeikan Univ. (Japan)
Tomonori Hiraki, Ritsumeikan Univ. (Japan)
Yuusuke Suenaga, Ritsumeikan Univ. (Japan)
Tomonori Hanasaki, Ritsumeikan Univ. (Japan)
Ichiro Fujieda, Ritsumeikan Univ. (Japan)

Published in SPIE Proceedings Vol. 8258:
Organic Photonic Materials and Devices XIV
Christopher Tabor; François Kajzar; Toshikuni Kaino; Yasuhiro Koike, Editor(s)

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