Roll to roll production of 30 inch graph

We report that 30-inch scale multiple roll-to-roll transfer and wet chemical doping considerably enhance the electrical properties of the graphene films grown on roll-type Cu substrates by chemical vapor deposition. The resulting graphene films show a sheet resistance as low as ~30 Ω/sq at ~90 % transparency, which is superior to commercial transparent electrodes such as indium tin oxides (ITO). The monolayer of graphene exhibits sheet resistances as low as ~125 Ω/sq with 97.4% optical transmittance and half-integer quantum Hall effect, indicating the high quality of these graphene films. As a practical application, we also fabricated a touch screen panel device based on the graphene transparent electrodes, showing extraordinary mechanical and electrical performances.