Non-fluorinated superhydrophobic film with high transparency for photovoltaic glass covers

Nowadays, there are several ways to prepare transparent superhydrophobic films for photovoltaic glass covers, but majority involve fluorosilane modifications, which are not only environmentally unfriendly but also can be hazardous to individuals. In this research, a non-fluorinated dip-coating method was proposed to prepare the film with a superhydrophobic layer and an antireflective layer. The antireflective layer with a network of nanopore-like structures was formed through a pore-forming agent. Then the superhydrophobic layer was deposited on above layer by simple immersion. Superhydrophobic silica nanoparticles would adhere to those structures, thus reducing the nanopore size and roughness, and increasing the transmittance. Finally, to enhance the films' self-cleaning abilities, a non-fluorinated silane modifier Hexamethyldisilazane (HMDS) was adopted. The film presented the average transmittance of 93.66 % in the wavelength range of 300 similar to 1200 nm. The average static water contact angle (WCA) was 152 degrees. In the self-cleaning test no dust was retained on the surface. The UV resistance test revealed that the film possessed outstanding UVA resistance. Moreover, the superhydrophobic films maintained transmittance stability against acidic (pH = 2) and deionized water (pH = 7) immersion. This environment friendly and low-cost preparation creates possibilities in photovoltaic glass covers and other fields.