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A series of new organic semiconductors based on s-indaceno[1,2-b:5,6-b′]dithiophene-4,9-dione was successfully synthesized and characterized. The electron withdrawing carbonyl group lowers the LUMO energy levels, leading to increased electronegativities, which is beneficial for high photo-stability in air. The n-alkyl substituted compounds, 1c and 1d, crystallize with the rigid coplanar systems packed into slipped face-to-face π-stacks. Interestingly, 1c and 1d also show liquid crystalline behaviors, which give highly ordered molecular packing over large area.

Two new azapentacene derivatives 9,10-dibromo-6,13-bis(triisopropylsilylethynyl)-1-azapentacene (a) and 8,9,10,11-tetrachloro-6,13-bis(triisopropylsilylethynyl)-1-azapentacene (b) were synthesized, and their FET properties were investigated. Compound b exhibits high and balanced ambipolar transport properties, with the hole and electron mobilities reaching up to 0.12 and 0.14 cm(2) V(-1) s(-1), respectively. This work suggests that chlorination to the N-heteropentacene framework is an efficient way for producing high performance ambipolar organic semiconductors.

We report the fabrication of simply structured and high performance organic complementary inverters based on an ambipolar organic semiconductor, 8,9,10,11-tetrachloro-6,13-bis-(triisopropylsilylethynyl)-1-azapentacene (4Cl-Azapen). Individual transistors using symmetric Au electrodes showed high and balanced performance, with good hole (up to 0.23 cm2V−1s−1) and electron (up to 0.21 cm2V−1s−1) mobilities. Integrated complementary inverters showed sharp inversions with high gains (>180) and negligible hysteresis. The inverters using low-cost electrodes, Ag and Cu, also exhibited high gains and high noise margins (>75% of the ideal value).