Study Of The Preparation And Properties On Composite FTO/SiO₂ Film With Transparent And Conductive

In this paper, FTO/SiO2 composite transparent conductive film has been got by sol-gel method. The raw materials are SnCl2·2H2O, NH4F and TEOS. The various parameters of film preparation were studied, including the configuration of FTO and SiO2 sol, matrix processing, coating method, heat treatment, etc. According to adhesion test and optical performance test, the effect of F doping concentration, heat treatment temperature and film thickness on the film crystal structure, surface morphology and optical properties were all studied by XRD, UV-Vis and Square resistance.The conclusions of the experiment:the optimal configuration of SiO2 sol:EtOH/ TEOS/H2O= 4:2:1 (volume ratio), PH= 2-3. The optimal configuration of SnO2 sol:sol concentration of 0.4mol/L, H2O/SnCl2·2H2O= 4 (mol ratio), PH= 2-3;The performance of FTO/SiO2 is better than FTO film. In the same circumstances, FTO/SiO2 film resistance value is less than FTO film. Because the SiO2 film can block appropriately Na+and Ca+into the FTO film during the heat treatment process, in this case to avoid the formation of acceptor within the band gap energy level and reduce the conductivity of film.In FTO/SiO2 film, The appropriate amount of F doping can significantly improve the film conductivity and transmittance; with the increase of heat treatment temperature the film conductivity increased, but little effect on transmittance; with the increase of film thickness the film conductivity increase, but the transmittance decreased.When the F doping concentration is 5mol%, heat treatment temperature at 500℃, and film thickness is 1+3c (1 layer of SiO2 film,3 layers of FTO film), the FTO/SiO2 film has the best optical properties, the average light transmission rate is up to 85%, and sheet resistance is 260Ω/□.