Facile preparation of a water-based antireflective SiO2 film with high transmittance for perovskite solar cells

The synthesis of anti-reflective (AR) films has been increasingly focused on environmental friendliness and cost efficiency in order to realize green and sustainable development. Herein, a novel strategy for preparing a nanoporous SiO2 AR film with high transmittance by a sol-gel process is proposed based on a sodium silicate aqueous solution. Sodium ions in the as-prepared SiO2 AR film can be effectively removed by a facile washing process, and thus its refractive index can be regulated. Moreover, the pH value of the sol has a huge effect on the structure and properties of the SiO2 AR film. As a result, the AR film exhibited a high transmittance increase of 4.10% at 550 nm and an average transmittance increase by 3.51% in the wavelength range of 380-1100 nm compared with blank glass. In addition, the obtained water-based SiO2 AR film exhibited hydrophilicity and the water contact angle (WCA) can be regulated from 61 degrees to 8.4 degrees. When the AR film was applied to the upper surface of perovskite solar cells, the photoelectric conversion efficiency (PCE) revealed an improvement of 1.44% compared with the PCE of perovskite solar cells without the AR film. Therefore, this work can provide a facile and effective method to prepare water-based antireflective films with high transmittance for solar cells.