Five-ring-fused asymmetric thienoacenes for high mobility organic thin-film transistors: the influence of the position of the S atom in the terminal thiophene ring?

Journal of Materials Chemistry C Pub Date: 2019-02-27 DOI: 10.1039/C9TC00552H

Abstract

Two isomeric 2-hexyl substituted five-ring-fused asymmetric thienoacenes, i.e., thieno[1]benzothieno[3,2-b][1]benzothiophene (BTBTT6), in which the S atom in the terminal thiophene ring is located at different positions relative to the BTBT core, were synthesized and characterized. The syn-isomer forms bilayer “head-to-head” structures with herringbone packing modes within the layers in crystals, while the anti-isomer shows “head-to-tail” single-layer structures and sandwich-herringbone packing within the layers. The difference in packing structures involved the fact that the syn-isomer has stronger intermolecular interactions than the anti-isomer. Importantly, organic thin-film transistors (OTFTs) with near-ideal transfer and output characteristics were fabricated. Mobilities in the saturation and the linear regime (μsat and μlin) of up to 11.7 and 10.6 cm2 V?1 s?1, respectively, were achieved for the syn-isomer. This is the first report on OTFTs with both μsat and μlin above 10 cm2 V?1 s?1.

Graphical abstract: Five-ring-fused asymmetric thienoacenes for high mobility organic thin-film transistors: the influence of the position of the S atom in the terminal thiophene ring
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