Thickness dependence of mobility of pentacene planar bottom-contact organic thin-film transistors

We have fabricated planar bottom-contact organic thin-film transistors as a function of the thickness of the pentacene active layer. The highest mobility of the planar bottom-contact transistors is 0.47 cm²/Vs with only a 7 nm pentacene active layer. Our planar bottom-contact transistors show much higher mobility than conventional bottom-contact counterparts and even higher than the reported mobility values of top-contact counterparts for each thickness in the range from 2.5 to 10 nm. We find that spike at the edges of source and drain electrodes seriously deteriorates device performance.