Sol–gel preparation of SiO2/TiO2/SiO2–TiO2 broadband antireflective coating for solar cell cover glass

Triple-layer broadband abrasion-resistant antireflective (AR) coatings with excellent transmittance at 400–800 nm were designed with the aid of thin film design software (TFCalc™). SiO2, TiO2 and SiO2–TiO2 hybrid thin films with refractive indices of 1.44, 2.20 and 1.71 for the up, middle and bottom layers, were dip-coated from SiO2, TiO2 and SiO2–TiO2 hybrid sols by sol–gel process, respectively. SiO2 and TiO2 sols were prepared using tetraethyl orthosilicate (TEOS) and tetrabutyl orthotitanate (TBOT) as precursors and hydrochloric acid as catalyst. These designed triple-layer broadband AR coatings with an average transmittance as high as 98.4% at visible region were successfully obtained. Hexamethyldisilazane (HMDS) was further used to modify the surface of the AR coatings, which greatly improved the hydrophobicity of the coatings, and thus gave the AR coatings some self-cleaning property. These triple-layer abrasion-resistant broadband AR coatings with excellent transmittance in the visible region have potential value in the field of solar cells.