Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 92: Postersession DS/HL

HL 92.33: Poster

Donnerstag, 10. März 2016, 16:00–19:00, Poster A

Molecular order in dihexylsexithiophene thin film OFETs — Nina Zeilmann¹, Hans-Georg Steinrück^2,3, Manuel Johnson¹, Andreas Magerl², and •Rainer Fink¹ — ¹FAU Erlangen-Nürnberg, Physical Chemistry 2, Erlangen, Germany — ²FAU Erlangen-Nürnberg, LS Kristallografie, Erlangen, Germany — ³present address: SSRL, Menlo Park, USA

The end-functionalized sexithiophene Hex6THex represents a benchmark molecule for organic electronic applications such as OFETs due to its high charge carrier mobility. The latter is mainly related to the high degree of molecular ordering and π-π-stacking within the films. We have employed several probes to investigate the morphologies, molecular order and orientations of such films (thicknesses around 10 layers) prepared by vacuum sublimation at various substrate temperatures on inert SiO2 or Si3N4 substrates. X-ray reflectivity (XRR) probes the vertical electron density distribution that provides information on the thickness and density of individual sublayers. In particular, XRR yields high quality data on the arrangements of both the hexyl functionalities and the thiophene backbone. It is found that the projected length of both film features critically depends on the substrate temperature during deposition. Based on the experimental results, a model proposing the molecular orientation of the Hex6THex molecules with respect to the substrate is derived. These results are in very good agreement with AFM and micro-NEXAFS studies. Some correlations to the electrical transport properties of the films are drawn.