Moth-Eye Nanopillar Scaffolds Enable Transparent, Durable Superhydrophobic Coatings via Spatial Confinement and Physical Interlocking of Silica Nanoparticles

Transparent superhydrophobic coatings for photovoltaic (PV) cover glass must combine high optical transmission with durable liquid repellency and resistance to outdoor soiling. Here, we report a bioinspired bifunctional transparent superhydrophobic coating (BTSC) inspired by moth-eye optical gradients and sponge-spicule anchoring, comprising an inductively coupled plasma (ICP)-etched moth-eye-like nanopillar scaffold and a dip-coated fluorinated SiO2 nanoparticle layer. The nanopillars create a gradient effective refractive-index interface to suppress reflection, while their interstices spatially confine and physically interlock the nanoparticles, enhancing retention under mechanical stress. BTSC-glass exhibits a water contact angle of 153.9°, a peak transmittance of 95.3%, and an average transmittance of 94.3% over 380–1100 nm, exceeding the average transmittance of pristine glass (93.0%) by 1.3 percentage points, while retaining robust wettability after more than 100 sandpaper abrasion cycles and water-jet and sand-particle impact. It also exhibits thermal and acidic stability together with anti-icing and self-cleaning functionality. As PV cover glass, BTSC-glass yields a 1.61% relative increase in power conversion efficiency (PCE). After 14 days outdoors, its PCE decreased only from 19.60% to 19.50%, compared with 19.29% to 18.14% for pristine glass, corresponding to an approximately 11.5-fold reduction in PCE loss. This interfacial strategy integrates antireflection, superhydrophobicity, durability, and self-cleaning for photovoltaic cover glass.