title: X-ray based tools for the investigation of buried interfaces in organic electronic devices.
abstract: X-ray reflectivity combined with grazing incidence diffraction is a valuable tool for investigating organic multilayer structures that can be used in devices. We focus on a bilayer stack consisting of two materials (poly-(3-hexylthiophene)) (P3HT) and poly-(4-styrenesulfonic acid) (PSSA) spin cast from orthogonal solvents (water in the case of PSSA and chloroform or toluene for P3HT). X-ray reflectivity is used to determine the thickness of all layers as well as the roughness of the organic-organic hetero-interface and the P3HT surface. The surface roughness is found to be consistent with the results of atomic force microscopy measurements. For the roughness of P3HT/PSSA interface, we observe a strong dependence on the solvent used for P3HT deposition. The solvent also strongly impacts the texturing of the P3HT crystallites as revealed by grazing incidence diffraction. When applying the various PSSA/P3HT multilayers in organic thin-film transistors, we find an excellent correlation between the determined interface morphology, structure and the device performance.
authors.affiliation: Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria.
authors.forename: Alfred
authors.initials: A
authors.lastname: Neuhold
authors.forename: Hannes
authors.initials: H
authors.lastname: Brandner
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Ausserlechner
authors.forename: Stefan
authors.initials: S
authors.lastname: Lorbek
authors.forename: Markus
authors.initials: M
authors.lastname: Neuschitzer
authors.forename: Egbert
authors.initials: E
authors.lastname: Zojer
authors.forename: Christian
authors.initials: C
authors.lastname: Teichert
authors.forename: Roland
authors.initials: R
authors.lastname: Resel
keywords: Atomic force microscopy; Buried interface morphology; Grazing incidence X-ray diffraction; Mobility enhancement; Organic thin film transistor; X-ray reflectivity
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