Functional nanostructured surfaces in hybrid sol-gel glass in large area for antireflective and super-hydrophobic purposes

We demonstrate the modification of substrate surfaces by the fabrication of thin layer sub-wavelength nanostructures in sol-gel glass in large area on their surfaces. Compared with the traditional methods, the sol-gel method eliminates the etching step and therefore becomes more convenient. It is found that 90% of the height of nanostructures in the master can be transferred into the hybrid SiO2-TiO2 sol-gel glass in our experiment, while the horizontal size of the nanostructures can be replicated precisely. The optical characterization results show that the light reflectivity can be reduced by about 1% over a wide waveband ranging from 400 nm to 800 nm for ARS with a height of 32.4 nm. In addition, it is found that the contact angle of the substrate surface with sol-gel nanostructures has been significantly improved from about 47 degrees to 108 degrees. Therefore, it can be concluded that with a thin layer sol-gel glass sub-wavelength nanostructures, the substrate surface can be effectively modified to have the function of both anti-reflectivity and super hydrophobicity, which can find applications in the area of photovoltaic concentrating lenses for enhancing light transmission, antifogging purposes and others.