Mechanically robust and self-cleaning antireflection coatings from nanoscale binding of hydrophobic silica nanoparticles

Abstract

Antireflection coatings from silica nanoparticles exhibit promising applications in many energy-related areas such as solar-thermal and photo-voltaic systems. However, the coatings suffer from poor mechanical durability and low self-cleaning capability in outdoor conditions, which limit their practical application. Here, we create mechanically robust and self-cleaning antireflection coatings through nanoscale binding of hydrophobic silica nanoparticles with an organosilica binder. The coatings demonstrated nearly full transmission at desired wavelength of ∼550 nm, with peak transmittance up to 99.9%. Further advantage of these coatings is the combination of hydrophobic silica nanoparticles with the organosilica binder, resulting in hydrophobic and mechanically robust coatings, with water contact angle of 161° and hardness of 4.2 GPa. The coatings maintained their high transmittance under outdoor conditions for 3 months, which is largely attributed to their self-cleaning functionality resulting from super-hydrophobicity. We envision that the mechanically robust and self-cleaning antireflection coatings could find wide applications in outdoor conditions and other harsh environments.