TiO₂-SiO₂Composite Film With Anti-reflective And Self-cleaning Properties Was Prepared By Sol-Gel Method

With the advancement of technology, the consumption of energy is increasing. The development and utilization of solar energy has become one of the important ways to meet energy needs. The using of solar energy includes direct using and indirect using. Belong to the direct application of the solar energy. Solar collectors, solar water heating systems, greenhouses belong to the direct application of the solar energy; solar photovoltaic power generation and solar cell belong to the indirect use of the solar energy. For the study and application of the anti-reflection film on the surface of the solar device to improve the utilization of solar energy, people put a lot of manpower and material resources, as result the anti-reflective film performance was significantly improved. But its performance is seriously affected due to outdoor dust, organic material, the exhaust gas, atmospheric sediment contamination of the surface of the solar device. Therefore, the self-cleaning action of the solar device surface film is also important on the premise of antireflective function.In this thesis, on the base of prepared SiO2and TiO2films by sol-gel method and their performance studies, TiO2-SiO2anti-reflective self-cleaning composite film was prepared by using of the network structure and low refractive index of SiO2and self-cleaning effect of TiO2. The research works of this thesis as below.(1) Study firstly the respective performance of the SiO2film and the TiO2film. The transmittance peak of SiO2film was about98%by adding a pore-forming agent PEG and the film do not display catalytic performance. Low transmittance of TiO2films are improved to some extent with the increase of PEG amount and the transmittance peak of TiO2film increased from0.3%to about1.5%. The catalytic efficiency of TiO2film has also been improved to some extent, from0.3%to1.5%.(2) UV-visible spectrophotometer was used to test the transmittance of the composite film and to observe the ratio of precursors TEOS and TBTT, the molecular weight of PEG and dosage, as well as the amount of ethanol and other factors on the composite film transmittance. Results displayed that with the increase of TBTT relative content the transmittance of the composite film reduced accordingly, but the TBTT relative content of the film was lower the catalytic efficiency was restricted, so the experiment TBTT and TEOS volume ratio was1:5. With a corresponding increase in the transmittance of the increase in molecular weight of the PEG, but at the same time the stability of the sol was relatively poor. The increase of the amount of PEG on the transmittance rendered the irregular change. The experiment PEG molecular weight was4000and the amount was5.0g. The amount of ethanol should not be too much also should not be less, because the amount of ethanol indirectly impacted the rate of hydrolysis of the precursor and the rate of polymerization in the experiment, so in the experiment the amount of ethanol was60ml.(3) UV absorption device was used to test the catalytic effect of the film. The results showed that with the increase of TBTT relatively content in film and pulling speed of methylene blue catalytic efficiency was also a corresponding increase from3.331%(VTBTT: VTEOS=1:5) to33.77%(VTBTT:VTEOS=3:5), and then the PEG molecular weight was4000and the amount was5g; when VTBTT:VTEOS ratio was1:5, with the increases of PEG molecular weight, the catalytic efficiency of the composite film increased from0.66%(PEG1000) to14.52%(PEG10000) by a big margin. When the molecular weight of PEG was4000, with PEG dosage increases the catalytic efficiency of the composite film also increased corresponding with the amount of PEG used from0.331%(PEG used in an amount of1.5g) to15.19%(PEG used in an amount of7.5g). Taking into consideration such factors as the stability of the sol, the transmittance of the film with the catalytic efficiency, experiment used VTBTT and VTEOS ratio was1:5, the molecular weight of PEG was4000, the amount of5g and the pulling speed was4,000μm/s, then film transmittance peak was94.45%and the catalytic efficiency was13.52%.(4) The wetting angle meter was used to test the wetting properties of the film and it was found that the wetting properties of the composite film has been improved and the contact angle was less than15°, showing excellent wettability. It was observed that the transmittance of the film increased by3%-5%after being tempered, and the film exhibited good hydrophilic properties. The transmittance of the film reduced with the increase of TiO2relative content to some extent, but at the same time the catalytic efficiency of methylene blue was improved and achieved a fine combination of SiO2and TiO2.