Sol–gel-derived bayberry-like SiO2@TiO2 multifunctional antireflective coatings for enhancing photovoltaic power generation

Multifunctional coatings with broadband antireflective, durable, photocatalytic, and self-cleaning properties can enhance photovoltaic (PV) power generation by reducing the cleaning frequency and surface light reflection of PV modules. However, such coatings must be cost-effective and maintain their functional integrity under harsh outdoor environmental conditions. In this study, bayberry-like SiO 2 @TiO 2 nanoparticles were prepared by a sol–gel method, and their synthesis procedure and SiO 2 /TiO 2 sol volume ratio were optimized based on the refractive index, transmittance distribution, and methylene blue degradation rate. Afterwards, three-layer gradient refractive index broadband antireflective coatings (TGBA) of the optimized SiO 2 @TiO 2 nanoparticles were simulated theoretically and systematically characterized by various experimental techniques. The average transmittance of TGBA-coated glass was 8.93% (380–1800 nm) higher than that of undipped glass, and the photocatalytic performance of TGBA was verified by studying methylene blue photodegradation. The self-cleaning performance of TGBA was assessed by outdoor exposure, multi-cycle ultraviolet (UV) irradiation, and dark storage. The durability of TGBA was evaluated by conducting hardness measurements, abrasion testing, thermal cycling, and damp heat tests. The external quantum efficiency and J–V curves of TGBA-coated PV mini-modules revealed that their short-circuit current densities and power conversion efficiencies were substantially higher than those of undipped modules. The proposed multifunctional coatings can enhance PV power generation in harsh environments.