Design and preparation of superhydrophobic, broadband and double-layer antireflective coatings

As one of the most widely used optical films, antireflective coating (ARC) is widely used in lasers, display screens and solar cells. In this article, the double-layer ARC coating consists of a bottom layer using SiO2-TiO2 composite nanomaterials and a top layer of SiO2 modified with Hexamethyldisilazane (HMDS). The optimal parameters of the double-layer ARC were obtained through the simulation software Macleod. Meanwhile, the aging time of SiO2 sol, the volume fraction of HMDS, the annealing temperature, the dip-coating speed, and the volume fraction of TiO2, which affect the refractive index of the bottom and top layers, were explored in order to match the best parameters. By adjusting the structure of the bottom and top layers, the double-layer broadband ARC coating has a maximum transmittance of 97.6% in the 400-1800 nm spectral range, and an average transmittance of 96.0%. In addition, HMDS was used to modify the SiO2 sol to obtain a double-layer ARC with superhydrophobic properties with a hydrophobic angle of 151.4°. After the high-temperature and high-humidity environment test, the antireflective performance of the double-layer ARC has not changed significantly, demonstrating the broad prospects for application in large outdoor solar photovoltaic power plants. Moreover, this work not only provides a new method for adjusting the refractive index of the coating, but also opens up a new way for the preparation of broadband ARC.