Scalable, robust, omnidirectional antireflective, superhydrophobic coatings based on chitin nanofibers for efficient...

The growing demand for renewable energy has driven the development of antireflective coatings with excellent environmental durability and mechanical robustness, aimed at improving the efficiency of solar energy collection on solar panels. A robust and omnidirectional antireflective superhydrophobic coating with gradient refractive index (1.49 to 1.30 from bottom to top) was fabricated by using chitin nanofibers (ChNFs) and methylsilanized silica (Mesil) through lay-by-layer (LbL) self-assembly. The transmittance gains of a glass substrate with the ChNF/Mesil multilayered coating yielded 8.3 % at 550 nm and 7.6 % at 650 nm, respectively. The antireflective coating possessed superhydrophobicity with a water contact angle of 168° and a near-zero sliding angle of 0.3°. Even after 100 days of outdoor exposure in real environments, the coating maintained its antireflective superhydrophobic properties and self-cleaning performance. Compared with the solar panel (21.7 mV/cm²), the voltage per unit area of the ChNF/Mesil coated solar panel (36.9 mV/cm²) increased 0.7 % under the sunlight intensity of 59.3 × 10³ lx. This study not only provides a feasible approach to fabricate gradient refractive index coatings with excellent robust and omnidirectional antireflective superhydrophobic performance but also demonstrates that the gradient refractive index coatings hold great potential for self-cleaning photovoltaic panels in outdoor practical applications.