Hollow core-shell nanocoatings with gradient refractive index structure for enhanced photovoltaic performance

Hollow structure-based multifunctional coatings with broadband antireflectivity, self-cleaning performance, stability, and durability can be applied to photovoltaic (PV) modules to maintain high transmittance and increase solar cell power generation. This research prepared bilayer hollow composite nanoparticles by improving and optimizing the nanoparticle synthesis and volume ratios. The optimal volume ratio of hollow SiO2 to TiO2 was determined using refractive index, transmittance, surface area, photocatalysis, and thermogravimetry. With the modification effect of methyltriethoxysilane, the refractive index interval of the composite coating was obtained, while giving the coating better hydrophobicity. A three-layer broadband antireflective coating (HT-TGBA) with a gradient refractive index structure was prepared using pre-designed simulation software. Various morphological and structural characterizations of HT-TGBA nanoparticles were performed. The transmittance of HT-TGBA-coated glass was significantly improved compared with that of uncoated glass. Its self-cleaning properties were confirmed by photocatalysis and surface hydrophobicity. Damp heat, abrasion tests, and pencil hardness tests proved the excellent durability of HT-TGBA, and measurements of sustained water contact angles demonstrated its stability. The short-circuit current density and photoelectric conversion efficiency were significantly improved by dip-coating HT-TGBA onto mini-modules. These results demonstrate that HT-TGBA has broad application prospects, supporting future large-scale applications of composite coatings in PV modules.