Microstructure and electrothermal characterization of transparent reduced graphene oxide thin films manufactured by spin-coating and thermal reduction

We herein report the microstructure, optical and electrothermal properties of a series of reduced graphene oxide (RGO) thin films, which are manufactured by spin-coating (1 and 3 layers) of graphene oxide (GO) dispersion on a quartz substrate and thermal reduction at different temperatures of 800–1000 °C. The energy dispersive X-ray spectra reveal that the relative carbon content of RGO films increases from 84.3 at% to 93.5 at% with increasing the thermal reduction temperature from 800 °C and 1000 °C, whereas the oxygen content decreases from 15.7 at% to 6.5 at%. The optical transmittance of RGO1 (1 spin-coating layer) and RGO3 (3 spin-coating layers) films at 550 nm is characterized 32.7–40.8% and 6.3–12.4%, respectively, although it decreases with increasing the thermal reduction temperature. The sheet resistance of RGO1 films decreases from 5160 Ω/sq to 1220 Ω/sq with the increment of the thermal reduction temperature, whereas the sheet resistance of RGO3 films decreased from 1080 Ω/sq to 350 Ω/sq. The decreases in optical transparency and sheet resistance values of RGO thin films are due to the successful reduction of GO films with oxygen-related functional groups to electrically conductive graphene films during the thermal treatment. The RGO thin films are characterized to exhibit high performance electrothermal behavior in terms of uniform temperature distribution, controllable steady-state saturated temperatures, rapid temperature responsiveness, and electric power efficiency at input power densities.