Solution-processable dithieno[3,2-b: 2′, 3′-d] thiophene derivatives for organic thin-film transistors and complementary-like inverters

Solution-processable dithieno[3,2-b: 2', 3'-d] thiophene (DTT) derivatives, 2,6-bis(phenylethynyl) dithieno[3,2b: 2', 3'-d] thiophene (BP-Et-DTT) and 2,6-bis(thiophen-2-ylethynyl) dithieno[3,2-b: 2', 3'-d] thiophene (BT-Et-DTT) were synthesized and characterized as organic semiconductors for organic thin-film transistors (OTFTs). Thermal, optical, and electrochemical properties of the DTT-based semiconductors were investigated. The solution- sheared thin films based on DTT derivatives exhibited p-channel characteristics as an active layer in organic thin-film transistors. The highest hole mobility was 0.32 cm(2) V(-1)s(-1) based on BP-Et-DTT thin films. The thin films exhibited micrometer-sized crystalline fiber structures which were aligned along the shearing direction, resulting in fiber-alignment-induced charge-transport anisotropy. Furthermore, bulk heterojunction (BHJ) ambipolar transistors were fabricated with an optimized blending ratio of BP-Et-DTT and the representative n-channel semiconductor, PDIFCN2. Complementary-like inverters were fabricated based on the two identical ambipolar transistors, resulting in moderate voltage gains of up to 16.