Bias-stress characterization of solution-processed organic field-effect transistor based on highly ordered liquid crystals

Bias-stress effects in solution-processed, 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10) field effect transistors (FETs) are studied under negative and positive direct current bias. The bottom gate, bottom contact polycrystalline Ph-BTBT-10 FET with a hybrid gate dielectric of polystyrene and SiO2 shows high field effect mobility as well as a steep subthreshold slope when fabricated with a highly ordered smectic E liquid crystalline (SmE) film as a precursor. Negative gate bias-stress causes negative threshold voltage shift (Delta V-th) for Ph-BTBT-10 FET in ambient air, but Delta V-th rapidly decreases as the gate bias decreases and approaches to near zero when the gate bias goes down to 9V in amplitude. In contrast, positive gate bias-stress causes negligible Delta V-th even with a relatively high bias voltage. These results conclude that Ph-BTBT-10 FET has excellent bias-stress stability in ambient air in the range of low to moderate operating voltages. Published by AIP Publishing.