title: Bioinspired Superhydrophobic Highly Transmissive Films for Optical Applications.
abstract: Inspired by the transparent hair layer on water plants Salvinia and Pistia, superhydrophobic flexible thin films, applicable as transparent coatings for optoelectronic devices, are introduced. Thin polymeric nanofur films are fabricated using a highly scalable hot pulling technique, in which heated sandblasted steel plates are used to create a dense layer of nano- and microhairs surrounding microcavities on a polymer surface. The superhydrophobic nanofur surface exhibits water contact angles of 166 ± 6°, sliding angles below 6°, and is self-cleaning against various contaminants. Additionally, subjecting thin nanofur to argon plasma reverses its surface wettability to hydrophilic and underwater superoleophobic. Thin nanofur films are transparent and demonstrate reflection values of less than 4% for wavelengths ranging from 300 to 800 nm when attached to a polymer substrate. Moreover, used as translucent self-standing film, the nanofur exhibits transmission values above 85% and high forward scattering. The potential of thin nanofur films for extracting substrate modes from organic light emitting diodes is tested and a relative increase of the luminous efficacy of above 10% is observed. Finally, thin nanofur is optically coupled to a multicrystalline silicon solar cell, resulting in a relative gain of 5.8% in photogenerated current compared to a bare photovoltaic device.
authors.affiliation: Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Vüllers
authors.affiliation: Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.|Light Technology Institute (LTI), Karlsruhe Institute of Technology (KIT), Engesserstrasse 13, 76131, Karlsruhe, Germany.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Gomard
authors.affiliation: Light Technology Institute (LTI), Karlsruhe Institute of Technology (KIT), Engesserstrasse 13, 76131, Karlsruhe, Germany.
authors.forename: Jan B
authors.initials: JB
authors.lastname: Preinfalk
authors.affiliation: Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
authors.forename: Efthymios
authors.initials: E
authors.lastname: Klampaftis
authors.affiliation: Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Worgull
authors.affiliation: Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
authors.forename: Bryce
authors.initials: B
authors.lastname: Richards
authors.affiliation: Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Hölscher
authors.affiliation: Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
authors.forename: Maryna N
authors.initials: MN
authors.lastname: Kavalenka
mesh_terms: D032701:Biomimetics / Q000379:methods*; D057927:Hydrophobic and Hydrophilic Interactions; D053758:Nanoparticles / Q000737:chemistry; D055095:Optics and Photonics / Q000379:methods*; D018515:Plant Leaves / Q000737:chemistry; D013499:Surface Properties
keywords: biomimetics; organic light emitting diodes; solar cells; superhydrophobic; transparent