On Antireflective Coatings with Stable Hydrophobicity for Solar Tube

Antireflective coatings with stable hydrophobicity for solar tube were prepared via sol-gel method and hexamethyldisilazane (HMDS) treatment. The coatings have a high porosity, groove-like surface morphology and a big static water contact angle. As a result, the coatings exhibit high transmittance even in high humidity environments. The transmittance peak can reach up to 99.02% which increased by 7% compared with the substrate and the wavelength band increased by more than 5% is from 438nm to 1000nm. After prolonged exposure to strong ultraviolet (UV) irradiation, the static water contact angle of the HMDS treated antireflective coatings decreased very small from 102o to 98o. In addition, the low-temperature tests showed the contact angle did not decline even at-50°C. The results suggest that the coatings prepared in present paper have stable hydrophobic and antireflective performance in the environment of strong UV radiation and low temperature.