Effect of the graphene doping level on the electrical and optical properties of indium tin oxide (ITO) films prepared by spray pyrolysis

A systematic study to optimize the electrical properties of ITO-graphene composite films deposited by spray pyrolysis method was investigated. The Hummers method was used for the synthesis of graphene oxide (GO) powder. Graphene was prepared by chemical reduction method from GO. To reduce GO, the most common reducing agent hydrazine hydrate at 3 ml per 100 mg of GO was used, Then, "ITO-graphene" composite films deposited by spray pyrolysis method. Structural, electrical and optical properties of films by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, two-point probe method, Hall Effect experiment and UV-Vis were analyzed. The results show that graphene sheets and "ITO-graphene" composite have been produced. The obtained ITO-graphene composite films showed an energy band gap from 3.62 to 3.57 eV and sheet resistance from 7.5 to 1.5 K Omega/sq in comparison with undoped ITO films. This study showed that adding graphene to ITO film without causing much change in structural properties and energy gap, reduces the resistance of ITO film about 75 % and increases its transparency up to 90 %. The results of this study may lead to ITO-graphene composite films be more interested in sensing and solar cells applications and composites.