Impact of annealing temperature on structural, morphological and optical properties of GO-TiO2 thin films prepared by spin coating technique

Abstract Thin films of graphene oxide – titanium dioxide were synthesized by spin coated on glass substrates. Annealing in air from room temperature to 300, 400 and 500 °C and at heating rate of about 0.16 °C/s affected the film structure, surface morphology and optical properties as studied by X-ray diffractometry, scanning electron microscopy, atomic force microscopy, and ultraviolet–visible transmittance spectroscopy. The film structure changed from amorphous to crystalline state with an increased annealing temperature. A crystalline TiO2 (i.e. anatase) formed at 500 °C. At a higher annealing temperature, the surface roughness and grain size of the films increased. The film transmittance reached a maximum of 80% in the visible region and the optical band-gap energy was changed from 3.00 to 3.71 eV. Therefore, these films could be applied in perovskite solar cells for energy harvesting.