Two-dimensional extended pi-conjugated anthracene-based molecules bearing 4-ethynyl-7-(5-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole at 2,6-and 9,10-substitution positions

Abstract

New 4-ethynyl-7-(5-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole-containing conjugated molecules were synthesized via the Sonogashira coupling reaction. The synthesized anthracene-based molecules showed good solubility in common organic solvents and had good self-film-forming properties. The semi-conducting properties of the two synthesized pi-conjugated molecules, 4 and 8, were evaluated by using the molecules in organic thin-film transistors (OTFTs). As-spun films of these molecules showed fairly high charge carrier mobilities, 0.010-0.10 cm(2) V-1 s(-1) (I-ON/I-OFF > 10(3)). The high charge carrier mobilities were attributed to the strong intermolecular interaction, which resulted in easy crystallization and dense coverage of the insulator surface. In addition, the two molecules were used to fabricate organic photovoltaic (OPV) cells with methanofullerene [6,6]-phenyl C-61-butyric acid methyl ester (PC61BM), without thermal annealing. The best preliminary results were obtained for the photovoltaic cell containing 8: the open-circuit voltage, short-circuit current density, and fill factor were 0.76V, 1.65 mA cm(-2), and 0.44, respectively, and the overall power conversion efficiency (PCE) was 0.55%. (C) 2011 Elsevier B.V. All rights reserved.