Abstract

Organic field-effect transistors (OFETs)often deviate from ideal behaviors in air, which masks their intrinsicproperties and thus significantly impedes their practical applications. A keyissue of how the presence of air affects the ideality of OFETs has not yet beenfully understood. It is revealed that air atmosphere may exert a double-edgedsword effect on the active semiconductor layer when determining the ideality ofOFETs fabricated from p-type crystalline organic semiconductors. Upon exposingthe as fabricated device to air, water and oxygen mainly function as efficientp-type dopants for the active layer in the contact regions, enhancing chargecarrier injection and consequently improving device ideality. Nevertheless, asthe exposure time increases, the trapping centers for the injected minoritycharge carriers appear in the channel region, leading to degradation of deviceideality. Inspired by the double-edged sword behavior of air, a near-ideal OFETis achieved by ingeniously utilizing the doping/positive effect and eliminatingthe trapping/negative effect. The effect of air on the ideality of p-type OFETsis clarified, which not only illuminates some common observations of OFETs inair but also offers useful guidance for the construction of high-performanceideal OFETs.