Voltage-Gated Switching\nof Moire Patterns in\nEpitaxial Molecular Crystals

Studying molecular\nmaterials at the nanoscale allows\nus to gain\na deeper understanding of supramolecular structure formation and serves\nas the basis for rationally controlling the resulting interfacial\nproperties. Here, we describe the formation of extended Moiré\npatterns resulting from the assembly of dipolar π-conjugated\nmolecules on highly oriented pyrolytic graphite at the liquid–solid\ninterface as characterized by scanning tunneling microscopy (STM).\nBy switching the bias of the sample and thus the orientation of the\nexternal electric field in the vicinity of the STM junction, structural\nreorganization of the molecular building blocks and the resulting\norganic 2D crystal is induced and can conveniently be monitored <i>in situ</i> by the appearance and disappearance of the Moiré\npatterns. Importantly, the formation and loss of the Moiré\npatterns are fully reversible, providing exquisite control over epitaxial\nmolecular crystals. Our approach provides fundamental insights into\nthe supramolecular organization and resulting superstructure formation\nof incommensurable 2D lattices upon applying an electric field and\nenables the rational tuning of Moiré patterns as a key step\ntoward the potential integration of organic 2D crystals in molecular\nnanodevices.