Graphitizability of polymer thin films: an in situ TEM study of thickness effects on nanocrystalline graphene/glassy carbon formation

The morphology of the thin film, especially the thickness, greatly affects the graphitizability (ability to from ordered graphene/ graphite) and thus the properties of the resulting graphenoid material. Using in situ current annealing inside a transmission electron microscope (TEM), we followed the thickness-dependent structural evolution of the polymer film with a special focus on thickness effects.

Up to intermediate temperatures, the structural evolution during current annealing is similar to the evolution during thermal annealing of the thin films. At higher temperatures, thin samples form large graphene layers oriented parallel to the substrate, whereas in thick samples multi-walled cage-like structures are formed. MD simulations reveal a critical film thickness of 40 Å below which, the carbonized layers align parallel to the surface.