6H-Pyrrolo[3,2-b:4,5-b′]bis[1,4]benzothiazines: facilely synthesized semiconductors for organic field-effect transistors

Abstract

6H-Pyrrolo[3,2-b:4,5-b′]bis[1,4]benzothiazine (PBBTZ, 1) and its two 6-substituted derivatives (2 and 3) were conveniently synthesized. Their optical properties were studied by UV-vis and fluorescence spectroscopy, and electrochemical properties were investigated by cyclic voltammetry (CV). Good thermal stability was observed by thermogravimetric analysis. X-Ray analysis revealed a coplanar structure and a column stacking in the single crystal of compound 1. OFET measurements showed that 1–3 were p-type semiconductors. The performance of these devices displayed good reproducibility at ambient conditions. When devices containing 1 were fabricated on OTS-treated SiO₂/Si substrates at 60 °C, the best performance was achieved with the average hole mobility as high as 0.34 cm²V⁻¹ s⁻¹ and the on/off ratio about 10⁶–10⁷. This performance resulted from the well-ordered molecular packing as revealed by XRD and AFM analysis.