SKM 2023 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster Session I

CPP 17.18: Poster

Monday, March 27, 2023, 18:00–20:00, P3

Crystal Orientation and Surface Morphology in Thin Films of Poly-[3-(6-trifluorohexyl)thiophene] on Silicon and Graphene — •Alexander Much¹, Robert Kahl¹, Florian Meichsner², Mukundan Thelakkat², Thomas Thurn-Albrecht¹, and Oleksandr Dolynchuk¹ — ¹Experimental Polymer Physics, Martin Luther University Halle-Wittenberg — ²Applied Functional Polymers, University of Bayreuth

Semiconducting polymers gained much interest for use in electronic devices due to their easy processing from solution and mechanical flexibility. To improve the efficiency of organic electronic devices, it is crucial to understand and control the crystal orientation in thin films.

As recently found in films of poly-(3-hexylthiophene) (P3HT) on graphene, the interfaces to vacuum and graphene induce edge-on and face-on orientation, respectively [1]. We propose to influence the crystal orientation in polythiophenes by increasing the polarity of the end group of the side chains. Thereby, melt-crystallized thin films of poly-[3-(6-trifluorohexyl)thiophene] (P3CF3HT) studied by GIWAXS showed an increased and thickness-dependent tendency to face-on orientation not only on graphene, but also on silicon, which is inactive for P3HT. Furthermore, the film surface morphology probed by AFM strongly depends on the crystal orientation and the substrate. Our results validate the approach and open a pathway to control molecular orientation in polythiophenes.

[1] Dolynchuk et al., Macromolecules 54, 5429-5439, 2021