Electrical characteristics of highly-oriented F8T2 field-effect transistors formed on photo-aligned polyimide films

Abstract

We have fabricated organic field-effect transistors (OFETs) with a highly oriented active layer of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-bithiophene] (F8T2), which was formed with the help of a photo-aligned polyimide film. Two kinds of OFETs were fabricated: the current flow (channel) direction is parallel or perpendicular to the alignment direction of F8T2. Both OFETs showed normally-off p-channel transistor behavior, and almost no drain current hysteresis was observed. The OFETs exhibited an enhanced hole mobility (0.016 cm²V^-1s^-1) along the F8T2 alignment direction and a suppressed one (0.002 cm²V^-1s^-1) along the perpendicular direction.