Plasma Oxidation Followed by Vapor Removal for Enhancing Intactness of Transferred Large-Area Graphene

Transfering large-area graphene from the metal substrate to the target substrate is crucial to its wide potential applications in electromagnetic shielding, supercapacitor, DNA sequencing, seawater desalination, wearable electronics devices, display devices for OLEDs and touch-screen. Polymethyl methacrylate assisted transfer is being widely adopted, however, this technique tends to destroy graphene and to produce polymethyl methacrylate residues on the graphene surface. Here, we reduced the damage of graphene by improving the hydrophilicity and adhesion of graphene and substrate using O-2 plasma followed by heat treatment, and removed the polymethyl methacrylate residuals on the surface of graphene using hot acetone vapor. Both monolayer and multilayer graphene stacks were transferred onto the target substrate with dramatically improved surface hydrophilicity (contact angle decreased from 57.8 degrees to 6.0 degrees), and neither damage nor undesired residues were found. Especially, in the whole test band (400-1100 nm), all transferred graphene stacks exhibited transmittances higher than 90%. This work may bring opportunities for exploitation of large-area chemical-vapordeposited graphene in wider transparent and ultra-thin photovoltaic devices fields.