Visible and near infrared, wide-angle, anti-reflection coatings with self-cleaning on glass

Abstract

In this work self-cleaning and transparent surfaces were produced on glass surface with simultaneous wide-angle and good optical transmittance on the visible region. These properties are pursued by combination of multi-scale surface topology based on silica nanoparticles (SNPs), index grading and interference coating, as well as polytetrafluoroethylene (PTFE) self-assembly, using two approaches. In the first, two-layer approach (glass/SNPs/PTFE), the resulting samples presented a water contact angle (WCA) of 169° ± 2° with very low hysteresis, as well as significant antireflection. The second, three-layer approach (glass/SNPs/silica aerogel/PTFE), produced surfaces with WCA of 158° ± 2° with also very low hysteresis (<5°), in addition to normal transmittance of 99% or higher, which decreased less than 2% at 20° incidence. These results show that proper structure-coated glass, with a combination of interference and graded-index effects, may provide simultaneous wide-angle antireflection and self-cleaning properties.