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DS: Fachverband Dünne Schichten

DS 13: Poster

DS 13.44: Poster

Donnerstag, 20. März 2025, 18:00–20:00, P1

Molecular packing and alignment of prototypical acenes in organic 2D-material heterostructures — •Jan Vincent Schreiber and Gregor Witte — Philipps-Universität Marburg, Molekulare Festkörperphysik, 35032 Marburg, Germany

Heterostructures comprised of thin films of organic molecules and two-dimensional materials, notably monolayers of transition metal dichalcogenides, are emerging as a promising class of systems for applications in organic electronics. Unlike metallic surfaces, two-dimensional materials interact with adsorbates primarily through van der Waals forces, resulting in substrate-adsorbate interactions comparable in strength to intermolecular forces. This delicate balance means that even minor variations in surface characteristics or growth conditions can significantly affect the relative molecular alignment. A systematic investigation of the molecular model systems pentacene and 5,7,12,14-pentacenetetrone allows comparison of the influence of electrostatic forces on the film alignment. Techniques ranging from scanning tunnelling microscopy to optical polarisation microscopy highlight the necessity of understanding these interactions across multiple length scales. We demonstrate that for most substrates, specific molecular orientations optimize the system's structural energy, a phenomenon known as van der Waals epitaxy. Our findings emphasize the need for rigorous structural studies to unravel the interplay between molecular structure and substrate properties.

Keywords: Organic 2D-material heterostructures; Pentacene; Transition metal dichalcogenides; Van der Waals Epitaxie