Molecular ordering of high-performance soluble molecular semiconductors and re-evaluation of their field-effect transistor characteristics

Intermolecular hydrophobic interactions between long alkyl chains (fastener effect) can enhance the intermolecular overlap of the semiconducting layer of 2,7-dialkyl[1]benzothieno[3,2-b] [1] benzothiophenes (C-n-BTBTs; n=8, 10, 12), which contributes to improvements of the electric characteristics of their organic field-effect transistors. The molecular ordering of C-n-BTBTs in the thin-film state is elucidated by means of in-plane and out-of-plane X-ray diffraction of spin-coated thin films, and single crystal X-ray analysis.