Molecular Packing of High-Mobility Diketo Pyrrolo-Pyrrole Polymer Semiconductors with Branched Alkyl Side Chains

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• 作者：Xinran Zhang ; Lee J. Richter ; Dean M. DeLongchamp ; R. Joseph Kline ; Matthew R. Hammond ; Iain McCulloch ; Martin Heeney ; Raja S. Ashraf ; Jeremy N. Smith ; Thomas D. Anthopoulos ; Bob Schroeder ; Yves H. Geerts ; Daniel A. Fischer ; Michael F. Toney
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：September 28, 2011
• 年：2011
• 卷：133
• 期：38
• 页码：15073-15084
• 全文大小：1395K
• 年卷期：v.133,no.38(September 28, 2011)
• ISSN：1520-5126

文摘

We describe a series of highly soluble diketo pyrrolo-pyrrole (DPP)-bithiophene copolymers exhibiting field effect hole mobilities up to 0.74 cm² V^鈥? s^鈥?, with a common synthetic motif of bulky 2-octyldodecyl side groups on the conjugated backbone. Spectroscopy, diffraction, and microscopy measurements reveal a transition in molecular packing behavior from a preferentially edge-on orientation of the conjugated plane to a preferentially face-on orientation as the attachment density of the side chains increases. Thermal annealing generally reduces both the face-on population and the misoriented edge-on domains. The highest hole mobilities of this series were obtained from edge-on molecular packing and in-plane liquid-crystalline texture, but films with a bimodal orientation distribution and no discernible in-plane texture exhibited surprisingly comparable mobilities. The high hole mobility may therefore arise from the molecular packing feature common to the entire polymer series: backbones that are strictly oriented parallel to the substrate plane and coplanar with other backbones in the same layer.