Salzmann, I.; Moser, A.; Oehzelt, M.; Breuer, T.; Feng, X.; Juang, Z.-Y.; Nabok, D.; Della Valle, R.G.; Duhm, S.; Heimel, G.; Brillante, A.; Venuti, E.; Bilotti, I.; Christodoulou, C.; Frisch, J.; Puschnig, P.; Draxl, C.; Witte, G.; Müllen, K.; Koch, N.: Epitaxial Growth of pi-Stacked Perfluoropentacene on Graphene-Coated Quartz. ACS Nano 6 (2012), p. 10874-10883
10.1021/nn3042607
Open Access Version (externer Anbieter)
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 π-stacked arrangement of coplanar molecules in “flat-lying” films, which exhibit an exceedingly low π-stacking distance of only 3.07 Å, giving rise to significant electronic band dispersion along the π-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.