Epitaxial growth of ?-stacked perfluoropentacene on graphene-coated quartz.

ABSTRACT: Chemical-vapor-deposited large-area graphene is employed as the coating of transparent substrates for the growth of the prototypical organic n-type semiconductor perfluoropentacene (PFP). The graphene coating is found to cause face-on growth of PFP in a yet unknown substrate-mediated polymorph, which is solved by combining grazing-incidence X-ray diffraction with theoretical structure modeling. In contrast to the otherwise common herringbone arrangement of PFP in single crystals and "standing" films, we report a ?-stacked arrangement of coplanar molecules in "flat-lying" films, which exhibit an exceedingly low ?-stacking distance of only 3.07 Å, giving rise to significant electronic band dispersion along the ?-stacking direction, as evidenced by ultraviolet photoelectron spectroscopy. Our study underlines the high potential of graphene for use as a transparent electrode in (opto-)electronic applications, where optimized vertical transport through flat-lying conjugated organic molecules is desired.

SUBMITTER: Salzmann I 

PROVIDER: S-EPMC3558021 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature