title: Nanostructuring of titania thin films by a combination of microfluidics and block-copolymer-based sol-gel templating.
abstract: Sol-gel templating of titania thin films with the amphiphilic diblock copolymer poly(dimethyl siloxane)-block-methyl methacrylate poly(ethylene oxide) is combined with microfluidic technology to control the structure formation. Due to the laminar flow conditions in the microfluidic cell, a better control of the local composition of the reactive fluid is achieved. The resulting titania films exhibit mesopores and macropores, as determined with scanning electron microscopy, X-ray reflectivity, and grazing incidence small angle X-ray scattering. The titania morphology has three features that are beneficial for application in photovoltaics: 1) a large surface-to-volume ratio important for charge generation with disordered hexagonally arranged mesopores of 25 nm size and a film porosity of up to 0.79, 2) enhanced light scattering that enables the absorption of more light, and 3) a dense titania layer with a thickness of about 6 nm at the substrate (bottom electrode) to prevent short circuits. An optical characterization complements the structural investigation.
authors.affiliation: Lehrstuhl für Funktionelle Materialien, Physik-Department E13, TU München, James-Franck-Strasse 1, 85747 Garching, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Rawolle
authors.forename: Matthias A
authors.initials: MA
authors.lastname: Ruderer
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Prams
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhong
authors.forename: David
authors.initials: D
authors.lastname: Magerl
authors.forename: Jan
authors.initials: J
authors.lastname: Perlich
authors.forename: Stephan V
authors.initials: SV
authors.lastname: Roth
authors.forename: Philipp
authors.initials: P
authors.lastname: Lellig
authors.forename: Jochen S
authors.initials: JS
authors.lastname: Gutmann
authors.forename: Peter
authors.initials: P
authors.lastname: Müller-Buschbaum
mesh_terms: D044085:Microfluidics; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry*; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014965:X-Rays
chemical_list: D011108:Polymers; C009495:titanium dioxide; D014025:Titanium