Preparation and characterization of graphene-based fluorine doped tin dioxide thin films via spray pyrolysis technique

In this work, fluorine-doped tin oxide (FTO) and graphene/fluorine-doped (G-FTO) thin films were prepared using a low-cost spray pyrolysis method at a substrate temperature of 500 °C. For the FTOs, stannous chloride was dissolved in methanol and acetic acid to form the precursor solution. A 0.05 mole (M) of hydrofluoric acid was added to the precursor as an n-type impurity. The FTO thin film has an optical transmittance of 82% and electrical sheet resistance of 15 Ω/□. By meticulously integrating graphene into the optimal precursor solution of FTO, a significant improvement in the electrical conductivity of the prepared samples was achieved, leading to a reduction in the sheet resistance to 8 Ω/□ with a suitable optical transmittance of 79%. Structural, morphological, optical, and electrical properties of the prepared sample are investigated using X-ray diffraction, scanning electron microscope, UV spectroscopy, and four-point probe technique. The best performance of the FTO thin films is achieved utilizing 2.5 µmole/L of fluorine concentration at a substrate temperature of 500°C for a spraying exposer time of 20 min. The prepared sample has an electrical sheet resistance of 15 Ω/□, optical transmittance of 82%, and figure-of-merit of 91.2×10⁻⁴ Ω⁻¹.The addition of 0.4 µmole/L of graphene to the optimum FTO samples enhances the performance by a remarkable reduction in the electrical the sheet resistance to 8 Ω/□ and an acceptable reduction in the optical transmittance of 79%. The overall value of the figure-of-merit increased to 118.3×10⁻⁴ Ω⁻¹. The achieved results offer a high potential for adopting the prepared films for electronic and optoelectronic applications.