Organic thin-film transistors with bilayer of rubbed and evaporated hydrocarbon-based acene as active layer

We have investigated organic thin-film transistors (OTFTs) with a bilayer of rubbed and evaporated hydrocarbon-based acene 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) as an active layer. Using a rubbing process after spin-coating the C8-BTBT, crystallinity of the C8-BTBT thin film was improved and resultant superior OTFT characteristics were realized. We obtained a field-effect mobility of 1.6 cm2/Vs, a threshold voltage of −8.2 V, an on-off ratio of 106, and a subthreshold swing of 55 mV/decade.