Hydrophobic Group-Directed Self-Assembly of Gradient Porous Antireflective and Superhydrophilic Coatings on Photovoltaic Glass.

Coatings for photovoltaic glass urgently require antireflection, self-cleaning, and durability. Herein, we leveraged the surface free energy minimization effect of n-butyl hydrophobic groups in n-butyl glycidyl ether (BGE) to design a directed induction strategy, and successfully fabricated a gradient porous superhydrophilic and antireflective coating (BTKS-3). This effect drove the spontaneous migration of hydrophobic groups to the surface, creating a vertical concentration gradient that modulated the local chemical environment and solvent evaporation behavior during film formation, ultimately directing the formation of a gradient porous architecture. As a result, a gradient porous architecture formed spontaneously, going from a dense bottom layer to a porous top layer. Such a gradient enables stepwise refractive index matching from the glass substrate to air, boosting transmittance to 94.61%, which significantly outperforms bare glass and commercial antireflective coatings. Meanwhile, surface hydroxyl groups and nanoscale roughness endow the coating with superhydrophilicity (contact angle < 10°) and self-cleaning ability, along with good abrasion resistance and UV stability. Over, this work achieves synergistic optimization of optical, self-cleaning, and durability properties, offering a new paradigm for high-performance functional coatings on photovoltaic glass.