Abstract
The future success of organic electronic devices strongly depends on the ability to tailor the properties of thin films and interfaces. This calls for well-ordered thin films. However, their properties are dominantly influenced by the formation of the first molecular layer representing a template for further growth. The development of the first layer—in turn—depends on the fine balance of molecule–substrate and molecule–molecule interaction. The latter is usually attractive owing to van der Waals forces and causes the formation of islands and small crystalline grains. Here, we report on organic adsorbates exhibiting a repulsive intermolecular interaction. With increasing coverage, Sn-phthalocyanine molecules continuously rearrange on Ag(111) in a series of ordered superstructures. They always fill the surface terraces homogeneously and maximize the domain size. Thicker films also exhibit extremely large, monocrystalline grains and potentially enable bulk-like properties for thin films. The intermolecular interaction can be tuned by cooling and becomes attractive below ∼120 K.
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Acknowledgements
We thank F. Pollinger and the ESRF staff (T.-L. Lee, J. Zegenhagen) for their help during the XSW experiments. Financial support by the BMBF, the DFG and the ESRF is acknowledged.
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C.S. carried out all SPA-LEED experiments. S.H. participated in measurements on SnPc and I.K. in those on CuPc. XSW measurements were carried out by C.S., C.K., S.H. and I.K., and analysed by C.S. The experiments, data analysis and the manuscript were intensively discussed by C.S., C.K. and E.U. The paper was written by C.S. and C.K.
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Stadler, C., Hansen, S., Kröger, I. et al. Tuning intermolecular interaction in long-range-ordered submonolayer organic films. Nature Phys 5, 153–158 (2009). https://doi.org/10.1038/nphys1176
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DOI: https://doi.org/10.1038/nphys1176