Fabrication of multifunctional closed-surface SiO2-TiO2 antireflective thin films

Multifunctional thin films with superhydrophilicity, broadband antireflective performance, humidity resistance and outstanding mechanical robustness are essential as for their wide applications. However, so far, it remains a big challenge to take into consideration all these properties simultaneously due to the structural contradiction. Herein, we develop an effective dip-coating process to prepare hybrid thin films with mechanical robustness, high transmittance, super-durable moisture resistance, excellent photocatalytic activity and durable superhydrophilicity. Three different nanoparticles were deposited sequentially to construct the above thin film and the maximum transmittance of this particular thin film reached similar to 96.0%. The film surface showed an excellent superhydrophilicity (water contact angle approximate to 3.0 degrees), and antifogging property. The superhydrophilic thin film could keep its property for more than 20 days. The transformation from hydrophilicity to superhydrophilicity of the thin film could be readily realized by UV irradiation. Moreover, its self-cleaning property could be retained after reduplicative storage and UV illumination cycles. Sponge washing test, water drop impact, pencil hardness test and tape peeling test revealed that the thin film possessed outstanding mechanical robustness. Methylene blue photodegradation was chose to weigh the photocatalytic activity of the hybrid thin film. In addition, the thin film shows excellent humidity-resistance at high temperature, and the excellent performance is due to its closed-surface structure. The closed-surface multifunctional thin films pave way toward use in solar cells, high-rise architecture windows under severe climate conditions.