Mechanically robust, humidity-resistant, thermally stable high performance antireflective thin films with reinforcing silicon phosphate centers

- A hierarchically nanoporous antireflective thin film was fabricated from an acid-catalyzed hybrid silica sol.
- The antireflective thin film shows mechanically robust, humidity-resistant and thermally stable properties simultaneously.
- The maximum/average transmittances (400-800 nm) of K9 glass increase from 92.1%/92.0% to 99.7%/98.8%, respectively.
- Silicon phosphate centers cross-link the entire thin film, resulting in a 5H pencil hardness and 5A adhesion to substrate.

High performance, function durability, thermal stability and mechanical robustness have long been pursued for advanced antireflective thin films. In the current work, we developed a novel and effective approach to fabricate mechanically robust, humidity-resistant, thermally stable high-performance antireflective thin films with reinforcing silicon phosphate centers from an acid-catalyzed hybrid silica sol. The thin film has a hierarchically nanoporous structure, resulting in favorable antireflective properties. After being coated with the antireflective thin film, the maximum and average transmittances of K9 glass increase from 92.1% and 92.0% (400-800 nm) to 99.7% and 98.8% (400-800 nm), respectively. In addition, the thin film shows favorable humidity-resistance and heat-resistance, and these extraordinary performances are attributed to its rich heat-resistant and hydrophobic groups. Moreover, mechanical strength measurements indicate the thin film has extraordinary 5H pencil hardness and 5A adhesion to substrate because of the formation of silicon phosphate centers in the thin film, which significantly reinforce the thin film. These high-performance antireflective thin films are promising in solar energy utilization, especially in solar cells.