Fabrication of transparent, durable and self-cleaning superhydrophobic coatings for solar cells
A superhydrophobic coating with high transparency and ultrahigh adhesive force is designed and prepared for the glass covers of solar cells, which also exhibits excellent thermal stability and strong acid-base corrosion resistance. SiO2 with antireflection effect, as the bottom layer, is prepared via Plasma Enhanced Chemical Vapor Deposition (PECVD) method, then Glycidoxypropyltrimethoxysilane (KH560) hydrolysis condensation which hydroxyl is formed at the two ends is used to form a network structure as the middle connecting layer. The top superhydrophobic layer is obtained by hydrophilicity SiO2 modifed by hexamethyldisilazane (HMDS). The structure of this superhydrophobic surface is similar to the bilayer structure of phospholipid in cell membrane. The superhydrophobic glass exhibits high optical transmittance which can reach at 94% in the visible region. The results show that the superhydrophobic glass has excellent self-cleaning performance (WCA=153°). Moreover, the surface shows remarkable stability against strong acid, strong alkali, and the impact of water drops and sands. Finally, a simple simulation of silicon-based superhydrophobic glass solar cells was carried out, and a long-term outdoor experiment was carried out to test their photoelectric conversion efficiency. During the two-month study period, the power conversion efficiency (PCE) of solar cell module was reduced to 13.01% due to the dust deposited naturally, which was significantly lower than that of superhydrophobic glass cover module with self-cleaning function (PCE was 14.21%).