Regensburg 2019 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 9: Topical session (Symposium MM): Correlative and in-situ Microscopy in Materials Research
MM 9.8: Talk
Monday, April 1, 2019, 18:15–18:30, H44
In-operando studies on organic field-effect transistors — •Manuel Johnson1, Tim Hawly1, and Rainer H. Fink1,2 — 11Lehrstuhl für Physikalische Chemie II, FAU Erlangen-Nürnberg, Germany — 2CENEM, FAU Erlangen-Nürnberg, Germany
Organic semiconducting films bear high potential for device applications such as field-effect transistors (OFETs). Understanding the correlation between microstructure and charge transport within the active layer of these devices is crucial to achieve high field-effect mobilities. To ad-dress this issue we performed spatially-resolved spectroscopic measurements to correlate the spectroscopic changes with the local microstructure of our thin organic film devices. In our stud-ies we investigated pentacene and different thiophene derivative based OFETs. We could ob-serve small variations in the density of unoccupied states during device operation using X-ray microscopy and local NEXAFS spectroscopy. We attribute the spectral modifications in terms of intramolecular polarization for molecules located at the organic/insulator interface. Spatially-resolved XPS measurements offer additional insight into the absolute change in binding energy (BE). Our recent results contradict the findings from Nagamura et al. that conducted similar studies and reported a BE increase when applying a gate voltage [1]. We discuss the observed decrease in the BE with respect to the operation state of the OFET device and show that it can be used for a visualization of a charge accumulation layer inside the active layer. This research is funded by the DFG within GRK 1896.
[1] N. Nagamura, et al., Appl. Phys. Lett. 106, 2015, 251604