Cold Wall Chemical Vapor Deposition Graphene-Based Conductive Tunable Film Barrier

In this paper, we report on a continuous, flexible, and transparent graphene film obtained by cold wall chemical vapor deposition (CVD) on Cu foil. The good continuity of the graphene film, obtained in optimized conditions (e.g., pretreatment to increase copper grain size, Ar flow during synthesis to control Cu sublimation) was successfully transferred on a PET substrate to be applied with a double function of window electrode and barrier film. PET film after a single layer graphene deposition showed good performance: a sheet resistance of 0.6 kΩ/sq, a low reduction of transmittance in comparison with the bare polymer (only ∼3% in a large range), an increment of 95% for the oxygen barrier properties, and a very low water vapor transmission rate (WVTR) (∼96% reduction respect to PET substrate). This shows that graphene film may be an important alternative to conventional transparent electrode materials. We also speculate on the possibility to modulate polymer permeability at the nanoscale just applying a controlled-nanoporosity graphene layer.