Comparison of the properties of various sol-gel derived anti-reflective (AR) coatings on SLS glasses

Anti-reflective (AR) coatings are optical coatings that increase the light transmission and therefore, reduce the theoretical reflection of an ordinary soda-lime-silica (SLS) float glass at the level of 8%. For an anti-reflective glass, the surface of glass should be coated with a film that has smaller refractive index than the glass. There is no inorganic material that would satisfy the low refractive requirements of a single-layer anti-reflective coating for commercial SLS glasses. Most SLS glasses used in windows and various containers have an index of refraction similar to1.52. This means 4.3% of the incident light is reflected from each glass surface. Generally, single layer antireflective coatings are based on SiO2 and on these single layer films, low refractive index is controlled by the amount and size of pores. In the present Study, the effects of solution composition and withdrawing speeds on AR properties of single layer films were investigated. Three different solution compositions namely, colloidal, basic and acidic SiO2 solutions were used in sol-gel dip coatings. The results showed that, highest AR properties were achieved with a film produced using base silica solution, on the other hand highest mechanical stability was achieved with a film produced using acidic silica solution.