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Optical and conductive properties of large-area liquid crystalline monodomains of terthiophene derivatives

Grzegorczyk, Wojciech J. and Savenije, Tom J. and Valeton, Josue J. P. and Fratiloiu, Silvia and Grozema, Ferdinand C. and de Leeuw, Dago M. and Siebbeles, Laurens D. A. (2007) Optical and conductive properties of large-area liquid crystalline monodomains of terthiophene derivatives. JOURNAL OF PHYSICAL CHEMISTRY C, 111 (49). pp. 18411-18416.

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Official URL: http://dx.doi.org/10.1021/jp076180h

Abstract

The optical and conductive properties of the liquid-crystalline organic semiconductor 5,5 `'-bis (5-hexyl-2-thienylethynyl)-2,2':5',2 `'-terthiophene (TR5-C6) spin-coated on rubbed polyimide (PI) were studied. The absorption of light linearly polarized parallel to the rubbing direction largely exceeds that in the perpendicular direction. In contrast, a small anisotropy in the photoconductance was found from time-resolved microwave conductivity (TRMC) measurements. From analysis of the optical data, it is inferred that the terthiophene chains in the TR5-C6 molecules are oriented along the PI rubbing direction with a tilt angle of 53 degrees with respect to the plane of the substrate. The absence of a strong anisotropy in the mobility of charge carriers can be understood on the basis of calculated charge transfer integrals, which were found to be comparable for charge-transfer steps in different directions. This is due to arrangement of the molecules in a herringbone structure. Due to the relatively small values of the charge transfer integrals, it is likely that charge transport in TR5-C6 occurs via polaron hopping between localized states.

Item Type:Article
Subjects:Physical Science > Nanophysics
Material Science > Nanochemistry
ID Code:1257
Deposited By:Anuj Seth
Deposited On:15 Dec 2008 15:29
Last Modified:15 Dec 2008 15:29

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