Improving the electrical performance of PDI8-CN 2 bottom-gate coplanar organic thin-film transistors

In this paper, we report on the fabrication of n-type bottom-gate bottom-contact transistors, based on evaporated films of a perylene diimide derivative (PDI8-CN2), displaying electrical performances comparable to their top-contact counterparts. By combining very thin (20 nm) electrodes and a cleaning process with oxygen plasma, indeed, bottom-contact devices with maximum mobility approaching 0.2 cm2/V s and a contact resistance lower than 35 kΩ cm at low VDS values have been achieved. AFM analyses reveal that the improved electrical responses are accompanied by the optimized PDI8-CN2 film morphology which, very significantly, exhibits similar features on the gold and dielectric (i.e., SiO2) surfaces.