Dresden 2020 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 86: Organic Electronics and Photovoltaics III
CPP 86.8: Talk
Thursday, March 19, 2020, 11:30–11:45, ZEU 260
In Situ and In Operando KPFM Studies on Hexadecafluoro-Copper-Phthalocyanine (F16PcCu) in OFET to Access Electrical Contact Resistance and Energy Level Alignment — •Pascal Schweitzer, Clemens Geis, and Derck Schlettwein — Justus Liebig University Gießen, Institute of Applied Physics
Contact resistances are considered the major limiter of performance of organic field effect transistors (OFET). Perfluorinated copper-phthalocyanine (F16PcCu) is a promising material as n-conductor to build complementary logical circuits. It is characterized by chemical stability under ambient conditions and a reasonably high charge carrier mobility. 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 to the source and drain metal contacts which allow for calculation of contact resistances. Thereby, the field-effect charge carrier mobility of F16PcCu was corrected for 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. We conclude, that tuning the energy level alignment and the interface effects to reduce contact resistances will lead to considerably improved performance of F16PcCu in OFET.