Contributed Talk - Thursday, 16 September I 10:40 AM (CEST)
Pascal Schweitzer: "KPFM-Analysis of Organic Field Effect Transistors"
Justus-Liebig-University Giessen, Germany
Contact resistances are considered a major show-stopper for organic field effect transistors (OFET). Perfluorinated copper-phthalocyanine (F16PcCu) is a promising material as n-conductor to build complementary logic circuits. It is characterized by chemical stability under ambient conditions. A reasonably high charge carrier mobility around 2E-3 cm²/Vs was estimated from device performance attenuated, however, by neglecting contact resistances. In this work, we used in operando Kelvin probe force microscopy under high vacuum to study the influence of contact resistances at the source and drain contacts on the OFET performance. Potentiometry at different applied external voltages revealed voltage drops at the interfaces. By correcting for such parasitic voltage drops, we were able to extract the charge carrier mobility that was free of contact effects. Significantly higher values were obtained. In situ KPFM during film growth on polycrystalline gold visualizes film formation and corresponding shifts of energy levels confirming the existence of an injection barrier.