Grafold-driven nucleation of pentacene on graphene

Folds in graphene-grafolds are frequently present even after transferring graphene layers, which were fabricated by chemical vapor deposition (CVD), onto SiO2 substrates. As we are showing in the present Letter, grafolds have a crucial role in determining the morphology of pentacene layers on graphene, and should be as such considered in designing fabrication protocols of pentacene-graphene devices. Our atomic force microscopy investigation of the initial stages of growth of vacuum-evaporated pentacene on CVD graphene shows three-dimensional growth at submonolayer coverages of pentacene. Moreover, islands were found to preferentially nucleate at the location of the grafolds. We interpret this behavior in terms of increased chemical reactivity of grafolds that was predicted in previous theoretical works.