Fabrication of highly conductive graphene/ITO transparent bi-film through CVD and organic additives- free sol-gel techniques

Indium tin oxide (ITO) still remains as the main candidate for high-performance optoelectronic devices, but there is a vital requirement in the development of sol-gel based synthesizing techniques with regards to green environment and higher conductivity. Graphene/ITO transparent bi-film was synthesized by a two-step process: 10 wt. % tin-doped ITO thin films were produced by an environmentally friendly aqueous sol-gel spin coating technique with economical salts of ln(NO3)(3 center dot)H2O and SnCI4( without using organic additives, on surface free energy enhanced (from 53.826 to 97.698 mJm(-2)) glass substrate by oxygen plasma treatment, which facilitated void-free continuous ITO film due to high surface wetting. The chemical vapor deposited monolayer graphene was transferred onto the synthesized ITO to enhance its electrical properties and it was capable of reducing sheet resistance over 12% while preserving the bi-film surface smoother. The ITO films contain the ln(2)O(3) phase only and exhibit the polycrystalline nature of cubic structure with 14.35 +/- 0.5 nm crystallite size. The graphene/ITO bi-film exhibits reproducible optical transparency with 88.66% transmittance at 550 nm wavelength, and electrical conductivity with sheet resistance of 117 Omega/sq which is much lower than that of individual sol-gel derived ITO film.