Synthesis and Characterization of Novel Semiconductors Based on Thieno[3,2-<i>b</i>][1]benzothiophene Cores and Their Applications in the Organic Thin-Film Transistors

The synthesis and characterization of four new organic semiconductors with thieno[3,2-<i>b</i>][1]benzothiophene cores and different π-bridge spacers are reported. Cyclic voltammetry measurement indicates that the materials have low energy levels of the highest occupied molecular orbitals and large band gaps. The single-crystal X-ray diffraction experiment reveals that 1,2-di(thieno[3,2-<i>b</i>][1]benzothiophenic-2-)ethylene (DTBTE) molecules have a nearly coplanar structure and crystallize into a herringbone arrangement with strongly intermolecular multiple S···S, S···C, and CH···π interactions. These interactions facilitate charge carrier transport. The DTBTE-based organic thin-film transistors (OTFTs) on an octyltrichlorosilane-modified SiO<sub>2</sub>/Si substrate exhibit good field-effect performance with the highest mobility of 0.50 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup>. Furthermore, the DTBTE-based OTFTs have been fabricated on a flexible polyethylene terephthalate substrate and showed a maximum mobility of up to 0.45 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup>, indicating its potential application as an organic semiconductor in the flexible OTFTs.