Anti-soiling effect of porous SiO2 coatings prepared by sol-gel processing

Thin films being composed of a nanoporous SiO2 network and silica nanoparticles were prepared on glass substrates by sol-gel processing. The surfaces combine anti-reflective (AR) and anti-soiling properties as demonstrated in laboratory testing and long term outdoor exposure. Films were characterized by scanning electron microscopy (SEM). It is shown that both, the structure of the nanoporous matrix as well as the particle density, contribute to this effect, the influence of relative humidity (RH) during dust exposure was investigated. Due to their generally improved solar transmittance and dust-repellant properties the coatings are believed to have a vast potential for many photovoltaic and solar thermal applications.