Control of device characteristics of ambipolar organic field-effect transistors using the hydroxyl in organic insulator

Using poly(vinylalcohol) with hydroxyl and poly(cyanoethylacrylate) without hydroxyl for the gate-insulating layer, we studied the influence of the hydroxyl on the device characteristics of ambipolar organic field-effect transistors (OFET) with copper–phthalocyanine used for the organic semiconductor. More than 10-fold higher mobility and a large threshold voltage were observed in the OFET with poly(cyanoethylacrylate). The ratio of the hole mobility and electron mobility of the ambipolar transistor with poly(vinylalcohol) was two times of that of the ambipolar transistor with poly(cyanoethylacrylate). The presence of the hydroxyl in the gate-insulating layer can control device characteristics of ambipolar OFETs.