9,10-Bis(phenylethynyl)anthracene-based organic semiconducting molecules for annealing-free thin film transistors

New anthracene-containing conjugated molecules have been synthesized through Stille coupling reaction. 2,6-Dibromoanthracene-9,10-dione was reacted with ethynylbenzene or 1-ethynyl-4-hexylbenzene to yield 2,6-dibromo-9,10-bis(phenylethynyl)anthracene 4 and 2,6-dibromo-9,10-bis((4-hexylphenyl) ethynyl)anthracene 5. Tributyl(5-hexylthiophen-2-yl)stannane was coupled through Stille reaction to generate two anthracene-based X-shaped molecules. They exhibit good solubility in common organic solvents and good self-film-forming properties. The semiconducting properties of the two molecules were evaluated in organic thin film transistors (OTFTs). Two conjugated molecules 7 and 8 exhibit fairly high charge carrier mobilities-as high as 0.010-0.014 cm² V^-1 s^-1 (I_on/I_off = 1.27 × 10⁷ to 4.38 × 10⁶) without thermal annealing process. The X-shaped molecules result in easy crystallization and densely cover the surface of a dielectric layer. This helps in attaining good network interconnection for the carrier transport channel, which is responsible for the relatively high carrier mobility in solution-processed OTFT.