Abstract
Sol-gel SiO2 antireflective (AR) coatings with nearly 100 % transmittance have great promise for optical fields. However, the poor environmental stability limits their uses. While hydrophobic modification can effectively improve the environmental stability, it also reduces the refractive index of coatings, which leads to transmittance deterioration. In this work, a simple two-step sol-gel process was used to create superhydrophobic SiO2 antireflective coatings with both high transmittance and excellent environmental stability. By applying the synergistic regulation on the refractive index of coating materials by water (H2O) and hexamethyldisilazane (HMDS), superhydrophobic SiO2 AR coatings with the refractive index ranging from 1.18 to 1.23 were obtained, satisfying the demand of commonly used substrates on the refractive index of coating materials and presenting transmittance around 100 % at the designed central wavelength. Furthermore, these superhydrophobic coatings were able to maintain a high transmittance level above 99.5 % for at least two months while exposed to an environment with 95 % relative humidity. The synergistic influence of H2O and HMDS on the SiO2 sols and the final coatings was investigated systematically, and the corresponding growth process of sol particles was discussed.
Published Version
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