Graded index sol-gel antireflection coatings
We explore graded index antireflection coatings that can reduce reflection of light at the ambient/cell or ambient/module boundary at all wavelengths and incidence angles. Simulations show that graded index coatings individually enhance absorption in solar cells across nearly the entire wavelength range. Silica sol-gel coatings with varying refractive indices deposited onto glass and silicon substrates are used to form graded index coatings, and the sol-gel layer processes have been adjusted so that the refractive indices are tunable from n=1.1 to n=1.5. Reflectance measurements also show that reflectivity decreases across the entire spectrum with added solgel multilayers.