Effects of Odd鈥揈ven Side Chain Length of Alkyl-Substituted Diphenylbithiophenes on First Monolayer Thin Film Packing Structure

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• 作者：Hylke B. Akkerman ; Stefan C. B. Mannsfeld ; Ananth P. Kaushik ; Eric Verploegen ; Luc Burnier ; Arjan P. Zoombelt ; Jonathan D. Saathoff ; Sanghyun Hong ; Sule Atahan-Evrenk ; Xueliang Liu ; Al谩n Aspuru-Guzik ; Michael F. Toney ; Paulette Clancy ; Zhenan Bao
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：July 31, 2013
• 年：2013
• 卷：135
• 期：30
• 页码：11006-11014
• 全文大小：541K
• 年卷期：v.135,no.30(July 31, 2013)
• ISSN：1520-5126

文摘

Because of their preferential two-dimensional layer-by-layer growth in thin films, 5,5鈥瞓is(4-alkylphenyl)-2,2鈥?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鈥揺ven effect in the strength of the intermolecular electronic coupling.