Spin coating a mixture of graphene oxide platelets, water, and an organic solvent by placing a drop of the mixture on a spinning substrate while blowing a drying gas onto the substrate and allowing the water and the organic solvent on the substrate to evaporate; and repeating the spin coating one or more times to form a graphene oxide film in contact with the substrate. An about 1-100 nm thick film of overlapping platelets of reduced graphene oxide.