Interfacial Chemical Welding of Component-Tailored Silica Networks for Durable Antireflective Coatings

Achieving precise refractive index matching alongside mechanical robustness remains a bottleneck for high-performance antireflective (AR) coatings. Herein, we propose a synergistic composition-regulation and interface-welding strategy that fundamentally decouples the intrinsic trade-off between optical transparency and mechanical integrity in porous optical thin films. By blending hollow silica nanoparticles (HSNs) and solid silica nanoparticles (SSNs) at precisely controlled volume ratios, the effective refractive index of the coating is continuously tunable over a range from 1.27 to 1.18. At the optimal ratio, the coating delivers a peak transmittance of 98.86% and a transmittance enhancement of 8.8%. Simultaneously, a mild vapor-phase ammonia treatment is employed to catalyze interfacial Si-OH condensation, thereby constructing a continuous Si-O-Si covalent network. This welding process preserves the hollow structure with negligible optical loss (<0.25%) while imparting exceptional durability. The coating maintains >98% transmittance after undergoing three separate durability tests: 80 abrasion cycles (500 g load), five sand impacts, and high-pressure water jetting. This work provides a universal pathway for fabricating multifunctional AR coatings with tailorable indices and superior durability for demanding outdoor photovoltaic and optoelectronic applications.