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Proceedings Paper

Solubility- and temperature-driven thin film structures of polymeric thiophene derivatives for high performance OFET applications
Author(s): Scott W. LeFevre; Zhenan Bao; Chang Y. Ryu; Richard W. Siegel; Hoichang Yang
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Paper Abstract

It has been shown that high charge mobility in solution-processible organic semiconductor-based field effect transistors is due in part to a highly parallel π-π stacking plane orientation of the semiconductors with respect to gate-dielectric. Fast solvent evaporation methods, generally, exacerbate kinetically random crystal orientations in the films deposited, specifically, from good solvents. We have investigated solubility-driven thin film structures of thiophene derivative polymers via spin- and drop-casting with volatile solvents of a low boiling point. Among volatile solvents examined, marginal solvents, which have temperature-dependent solubility for the semiconductors (e.g. methylene chloride for regioregular poly(3-alkylthiophene)s), can be used to direct the favorable crystal orientation regardless of solvent drying time, when the temperature of gate-dielectrics is held to relatively cooler than the warm solution. Grazing-incidence X-ray diffraction and atomic force microscopy strongly support that significant control of crystal orientation and mesoscale morphology using a "cold" substrate holds true for both drop and spin casting. The effects of physiochemical post-modificaiton on film crystal structures and morphologies of poly(9,9-dioctylfluorene-co-bithiophene) have also been investigated.

Paper Details

Date Published: 13 September 2007
PDF: 8 pages
Proc. SPIE 6658, Organic Field-Effect Transistors VI, 665812 (13 September 2007); doi: 10.1117/12.734032
Show Author Affiliations
Scott W. LeFevre, Rensselaer Polytechnic Institute (United States)
Zhenan Bao, Stanford Univ. (United States)
Chang Y. Ryu, Rensselaer Polytechnic Institute (United States)
Richard W. Siegel, Rensselaer Polytechnic Institute (United States)
Hoichang Yang, Rensselaer Polytechnic Institute (United States)

Published in SPIE Proceedings Vol. 6658:
Organic Field-Effect Transistors VI
Zhenan Bao; David J. Gundlach, Editor(s)

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