Optimizing the Superhydrophobicity of the Composite PDMS/PUA Film Produced by a R2R System

Maintaining the surface of solar cell panels free from contaminants to ensure their efficiency is a time-consuming and tedious task. Therefore, several methods of fabricating artificial transparent superhydrophobic surfaces have been reported to overcome that problem. However, most of the proposed fabrication methods are unscalable due to their complexity. Herein, a facile and cost-effective roll-to-roll system to fabricate a highly flexible and optically transparent polydimethylsiloxane/polyurethane acrylate superhydrophobic (FTPPS) film was proposed. The superhydrophobicity of the film was achieved by the combination of the surface roughness─the ultraviolet curable polyurethane acrylate (PUA) microstructures and the low surface energy material coating─the thin polydimethylsiloxane layer coated on PUA structures using capillary force. The superhydrophobicity of the FTPPS film was carefully optimized using various designs of PUA micro-post and the material properties of the film were examined systematically by different characterization techniques. The highest measured static water contact angle (WCA) of the FTPPS film is 153.3° ± 1.8 and its lowest water sliding angle is ∼9.5° ± 0.2. Moreover, the film still exhibited high WCAs of more than 142° even after being impacted multiple times by an adhesive probe or sand grains. This result demonstrates the high mechanical durability and flexibility of the as-fabricated superhydrophobic film. Finally, the potential application of the film as a protective cover for solar cells was also illustrated through the consistent photovoltaic conversion efficiency of the solar cell module covered by the film compared to that of the uncovered solar panel.