The role of graphene topography in initial stages of pentacene layer growth

Using atomic force microscopy, we probed growth of pentacene molecules on graphene that was fabricated by chemical vapor deposition (CVD) and transferred onto 300 nm-thick SiO₂ substrates. We observe that the folds on CVD graphene act as a potential barrier for the surface transport of pentacene molecules.  They are oriented either parallel or perpendicular to the folds, they are also predominantly oriented along the symmetry axes of graphene. Orientation of pentacene islands on graphene evaporated at room temperature has a wide distribution. On the contrary, most of the pentacene islands evaporated at 60°C are oriented at 30° with respect to the fold direction. In addition, we interpret the 3D growth of pentacene islands on graphene in terms of reduced polar components of surface energy on graphene investigated with contact angle measurements. The results were published in ACS Omega.