Investigations on structural, optical and electrical properties of microwave-assisted rGO:ZnO nanocomposite thin films

Abstract

The reduced graphene oxide:Zinc oxide (rGO:ZnO) nanocomposite films were fabricated by an optimized wet-chemical sol–gel derived spin-coating method. A simple, fast and effective microwave-assisted approach was adopted for the reduction of the graphene oxide. The influence of rGO on the microstructural and optoelectronic properties of ZnO was studied by varying the weight ratios of rGO. The results showed significant changes in the microstructural and optoelectronic properties of the rGO:ZnO composite films. X-ray diffraction analysis confirmed the polycrystallinity of the composite films with a preferential growth orientation of the crystallites along (002) plane. Good optical transparency in the visible wavelength region was observed in all the composite films. As the weight percentage of rGO increased from 0% to 20%, the red shift of the absorption edge was noticed, indicating the weak Burstein-Moss effect. The optical bandgap of ZnO reduces as the amount of rGO increases, resulting in the reduction of transmittance in the composite thin films. The sheet resistance and therefore the resistivity of the composite films decreases with the loading of rGO into ZnO matrix. The lowest values of sheet resistance and resistivity, and the highest Figure of Merit have been recorded for 10% rGO:ZnO composite film. The obtained results illustrate that the 10% rGO:ZnO composite film could be a potential candidate for electrode applications.