What could be the Highest Hopping Mobility in Organic Thin-Film Transistors?

ABSTRACTCharge transport properties of pentacene have been investigated by a joint experimental and theoretical study. The growth of pentacene on the substrates shows mainly two different polymorphic phases, a bulk phase and a thin-film phase. The thin-film phase is crucial for the charge transport in two-terminal and three-terminal devices such as organic Schottky diodes and organic thin film transistors, respectively. Experimentally, mobility in two-terminal devices is less by five orders of magnitude than that in three-terminal devices. We show here that this difference can be explained on the basis of strong electronic coupling between molecular dimers located in the ab-plane and relatively weak coupling between the planes (along the c-axis).