| Solar energy is known as clean energy source. Utilization of solar energy has been the major strategic in road of sustainable development to many countries. Therefore, the study of Photo-thermal and photo-voltaic technology are becoming more important. In order to increase Photo-thermal and photo-voltaic conversion efficiency and reduce energy loss caused by reflection on the components, anti-reflection coatings technology was often used. Anti-reflection coatings technology has become the hot use of photo-thermal and photo-voltaic researches today. In this paper, we have, the traditional sol-gel method improved for the preparation of anti-reflection coatings. High-transmittance and broadband anti-reflection coatings with good scratch resistance were prepared by acid-base composite catalysis and PEG-modified process.In this paper, the principles and applications of anti-reflection coatings as well as the sol-gel principles and influencing factors were described. The anti-reflection coatings and sol were prepared using different type of catalyst. The stability of the sols and the properties of anti-reflection coatings were (?). Catalysts different, principles of sol reaction are different. Experimental results (?)ase composite catalyzed approach combines the advantages of acid-catalyzed and bas(?) sol which made the base-catalyzed formed clusters of (?) form a network-like structure in the form of a combination of chemical bonds because ite HCl adding to.The transmittance peak of antireflective coatings obtained from acid and base composite catalyzed sol is much higher than the peak of coatings obtained from the acid catalyzed sol. Compare to the anti-reflection coatings from the base catalyzed sol, the peak of the coatings obtained from acid and base composite catalyzed sol declined but their hardness significantly increased. The experimental results show that it is feasible that dilute HCl was added directly into base catalyzed Sol. The addition of dilute HCl make the pH of sol changed and make chain reaction mechanism formed in acid catalyzed sol. The SiO2chains cross-link with each other, form network structure, make the particles and clusters formed by the base catalyzed sol connected to each other and form a suitable size of pore. Then the ideal refractive index was obtained and the transmittance of the sample was improved. The transmittance peak of the coatings obtained from acid and base composited sol can reach to98.7%while the hardness can reach4H.On the basis of the acid-catalyzed sol the PEG were joined to the sol for its modification which made the preparation process simplified and got a higher peak and a wider band transmittance. PEG were added so that the surface morphology undergone great changes. There had been groove-like structure which did not appear to acid-catalyze coatings and brought a positive impact for the broadband transmittance. By adding different molecular weight of PEG, the relationship between the anti-reflection coatings surface morphology and the transmittance and the molecular weight of the PEG was studied. By controlling the speed of the dip-pulling, the impact of anti-reflection film thickness on the transmittance peak position and the transmittance curve slope were studied. When pulling speed is large, we can only get a single peak and relatively steep of the slope of the transmission curve. When the pulling speed decreased to a certain value, the transmittance-wavelength curve trend was slowing down. When pulling speed is controlled2000μm/s, the peak of the transmittance of the anti-reflection coatings can be achieved f about99.4%at550nm, with the average transmittance of95.5%, increased of5.5%compared with the substrate.In this paper, the high transmittance and broadband anti-reflection coatings were hydrophobic modified. a large number of Si-OH groups were formed in the TEOS hydrolysis process. These groups remaining on the surface of the coatings made the coatings have a strong activity so that the coatings have a strong hydrophilicity. Substituted by inert groups, the hydrophilic Si-OH was replaced by the hydrophobic Si-O-Si (CH3) which made the surface of anti-reflection coatings showed hydrophobic properties with the static water contact angle up to102.93°. In the high-intensity ultraviolet light and in the environment of-40℃the coatings still had good hydrophobicity. |
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