title: Self-cleaning antireflective optical coatings.
abstract: Low-cost antireflection coatings (ARCs) on large optical surfaces are an ingredient-technology for high-performance solar cells. While nanoporous thin films that meet the zero-reflectance conditions on transparent substrates can be cheaply manufactured, their suitability for outdoor applications is limited by the lack of robustness and cleanability. Here, we present a simple method for the manufacture of robust self-cleaning ARCs. Our strategy relies on the self-assembly of a block-copolymer in combination with silica-based sol-gel chemistry and preformed TiO2 nanocrystals. The spontaneous dense packing of copolymer micelles followed by a condensation reaction results in an inverse opal-type silica morphology that is loaded with TiO2 photocatalytic hot-spots. The very low volume fraction of the inorganic network allows the optimization of the antireflecting properties of the porous ARC despite the high refractive index of the embedded photocatalytic TiO2 nanocrystals. The resulting ARCs combine high optical and self-cleaning performance and can be deposited onto flexible plastic substrates.
authors.affiliation: Department of Physics, University of Cambridge , J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
authors.forename: Stefan
authors.initials: S
authors.lastname: Guldin
authors.forename: Peter
authors.initials: P
authors.lastname: Kohn
authors.forename: Morgan
authors.initials: M
authors.lastname: Stefik
authors.forename: Juho
authors.initials: J
authors.lastname: Song
authors.forename: Giorgio
authors.initials: G
authors.lastname: Divitini
authors.forename: Fanny
authors.initials: F
authors.lastname: Ecarla
authors.forename: Caterina
authors.initials: C
authors.lastname: Ducati
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wiesner
authors.forename: Ullrich
authors.initials: U
authors.lastname: Steiner
mesh_terms: D049329:Nanostructures / Q000737:chemistry*; D055095:Optics and Photonics / Q000379:methods*; D011108:Polymers / Q000737:chemistry; D012031:Refractometry; D012822:Silicon Dioxide / Q000737:chemistry; D012993:Solar Energy; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D011108:Polymers; D012822:Silicon Dioxide; D014025:Titanium