Large-area graphene-based flexible transparent conducting films

A simple approach by direct synthesis of few-layer graphene sheets and transferring them onto flexible substrate is demonstrated. The hydrogen effect on the D band intensity of Raman spectra for few-layer graphene sheets synthesized by chemical vapor deposition (CVD) on Ni-evaporated silicon substrate is investigated by optimizing the mixing ratio of C₂H₄/H₂. While the Ni etchant is used to melt away the squeezed Ni layers between graphene sheet and silicon substrate, the graphene sheet is transferred onto polyethylene terephthalate film by a fishing method. It is found that the condition of graphene transfer strongly relies on the cooling rate of the film during CVD synthesis. The sheet resistance of the film decreases as the film thickness increases. A sheet resistance of 233 Ω/sq is obtained at a transmittance of 62%.