1. Effects of Odd–Even Side Chain Length of Alkyl-Substituted Diphenylbithiophenes on First Monolayer Thin Film Packing Structure.
- Author
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Akkerman, Hylke B., Mannsfeld, Stefan C. B., Kaushik, Ananth P., Verploegen, Eric, Burnier, Luc, Zoombelt, Arjan P., Saathoff, Jonathan D., Sanghyun Hong, Atahan-Evrenk, Sule, Xueliang Liu, Aspuru-Guzik, Alán, Toney, Michael F., Clancy, Paulette, and Zhenan Bao
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MOLECULAR structure of monomolecular films , *CHAIN length (Chemistry) , *BIPHENYL compounds , *THIOPHENES , *GRAZING incidence , *X-ray diffraction - Abstract
Because of their preferential two-dimensional layer-by-layer growth in thin films, 5,5′bis(4-alkylphenyl)-2,2′-bithiophenes (P2TPs) are model compounds for studying the effects of systematic chemical structure variations on thin-film structure and morphology, which in turn, impact the charge transport in organic field-effect transistors. For the first time, we observed, by grazing incidence X-ray diffraction (GIXD), a strong change in molecular tilt angle in a monolayer of P2TP, depending on whether the alkyl chain on the P2TP molecules was of odd or even length. The monolayers were deposited on densely packed ultrasmooth self-assembled alkane silane modified SiO2 surfaces. Our work shows that a subtle change in molecular structure can have a significant impact on the molecular packing structure in thin film, which in turn, will have a strong impact on charge transport of organic semiconductors. This was verified by quantum-chemical calculations that predict a corresponding odd-even effect in the strength of the intermolecular electronic coupling. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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