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 (Phi(TC)=3.535x10(-3) Omega(-1) cm) of the film was maximum with surface resistance (R-sh) of 14.7 Omega cm(-1), average transmittance (T) of 74.4% when F/Sn= 14 mol%, the reaction temperature of the sol was 50 degrees C, and the evaporation temperature was 600 degrees 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 (Phi(TC)=3.9x10(-3) Omega(-1) cm, R-sh=27.4 Omega cm(-1), T=80%) produced by chemical vapor deposition (CVD) method, the Phi(TC) 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.