Transparent and air stable organic field effect transistors with ordered layers of dibenzo[d,d]thieno[3,2-b;4,5-b′]dithiophene obtained from solution

In a search for solution processable and stable p-type semiconductors an analogue of pentacene namely dibenzo[d,d]thieno[3,2-b;4,5-b′]dithiophene (DBTDT) - was tested as an active layer in organic field effect transistors (OFETs). It was found that thin, continuous and transparent films of DBTDT can be obtained with the help of solution based zone-casting technique. This deposition technique allows one to produce highly oriented crystalline layers of DBTDT showing similar molecular arrangement as that of a single crystal. The zone-cast layers of DBTDT were successfully applied in a fabrication process of OFETs with Parylene C® used as the gate dielectric. The best parameters are exhibited by the devices with the bottom-gate, top contact configuration: charge carrier mobility of ca 0.02 cm²/Vs and threshold voltage of ca -50 V and performance of these OFETs remains unchanged after 1 months storage in air.