Properties of fluorine-doped tin oxide films prepared by an improved sol-gel process

Fluorine-doped tin oxide (FTO) films were prepared by an improved sol-gel process, in which FTO films were deposited on glass substrates using evaporation method, with the precursors prepared by the conventional sol-gel method. The coating and sintering processes were combined in the evaporation method, with the advantage of reduced probability of films cracking and simplified preparation process. The effects of F-doping contents and structure of films on properties of films were analyzed. The results showed the performance index (ΦTC=3.535×10−3 Ω−1 cm) of the film was maximum with surface resistance (Rsh) of 14.7 Ω cm−1, average transmittance (T) of 74.4% when F/Sn=14 mol%, the reaction temperature of the sol was 50 °C, and the evaporation temperature was 600 °C in muffle furnace, and the film has densification pyramid morphology and SnO2−xFx polycrystalline structure with tetragonal rutile phase. Compared with the commercial FTO films (ΦTC=3.9×10−3 Ω−1 cm, Rsh=27.4 Ω cm−1, T=80%) produced by chemical vapor deposition (CVD) method, the ΦTC value of FTO films prepared by an improved sol-gel process is close to them, the electrical properties are higher, and the optical properties are lower.