Insights into the optical and electrical properties of controlled reduced graphene oxide prepared by a green and facile routes

Three distinct homogeneous multilayer self-standing thin films, composed of stacked reduced graphene oxide (rGO) planes, were produced by improved Hummer’s method. In order to investigate their structural, electrical, and optical properties, the samples were characterized by Raman spectroscopy, field emission scanning electron microscopy (FESEM), four-point probe measurements, and Fourier-transform infrared spectroscopy (FTIR). The Raman spectra of the samples indicate the presence of minor surface defects and a relatively low oxygen content of rGOs. The FESEM images obtained from the samples reveals a smooth sheet-like surface with few wrinkles. Additionally, the cross-sectional images provide confirmation of the presence of multi-stacked layer structures. Based on the resistance decreasing by about 0.35 to 0.65 percent per kelvin within the region of ambient temperature, the electrical resistance vs. temperature curves imply semiconductive behavior in the rGOs. The FTIR analysis of the samples conducted within the wavelength range of 2.5 to 25 um, demonstrates a significant absorption value exceeding 90%. This observation shows that the developed materials possess favorable characteristics making them an excellent absorber candidate as for sensing detectors in the infrared range. We systematically analyzed and confirmed that the structural as well as optical and electrical properties of our obtained rGOs, may be fine-tuned by adjusting the initial reactants concentration and annealing temperature.