title: Calcination-free micropatterning of rare-earth-ion-doped nanoparticle films on wettability-patterned surfaces of plastic sheets.
abstract: We demonstrate a patterning technique of rare-earth-ion-doped (RE) nanoparticle films directly on wettability-patterned surfaces fabricated on plastic sheets in one step. Self-assembled monolayers consisting of silane-coupling agent with hydrophobic groups were fabricated on plastic sheets. UV-ozone treatments were performed through a metal mask to selectively remove the self-assembled monolayers in a patterned manner, resulting in the formation of wettability-patterned surfaces on plastic sheets. Using a water dispersion of Er(3+) and Yb(3+)-codoped Y2O3 nanoparticles at a diameter of 100 nm, RE-nanoparticle films were fabricated on the wettability-patterned surfaces by a dip-coating technique. By adjusting the concentration of RE-nanoparticle dispersion, withdrawal speed, and withdrawal angle, amount of RE-nanoparticles, we were able to control the structures of the RE-nanoparticle films. Fluorescence microscope observations demonstrate that visible upconversion luminescence and near-infrared fluorescence were emitted from the RE-nanoparticle films on the wettability-patterned surfaces. This technique allows for the fabrication of flexible emitting devices with long-operating life time with minimized material consumption and few fabrication steps, and for the application to sensors, emitting devices, and displays in electronics, photonics, and bionics in the future.
authors.affiliation: Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan. Electronic address: watasato@rs.noda.tus.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
authors.forename: Yudai
authors.initials: Y
authors.lastname: Hamada
authors.affiliation: Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hyodo
authors.affiliation: Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Soga
authors.affiliation: Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
authors.forename: Mutsuyoshi
authors.initials: M
authors.lastname: Matsumoto
keywords: Dip-coating; Flexible device; Near-infrared fluorescence; Rare-earth-ion-doped nanoparticle; Two-photon absorption; Upconversion luminescence; Wettability-patterned surface