title: Vacuum-free, maskless patterning of Ni electrodes by laser reductive sintering of NiO nanoparticle ink and its application to transparent conductors.
abstract: We introduce a method for direct patterning of Ni electrodes through selective laser direct writing (LDW) of NiO nanoparticle (NP) ink. High-resolution Ni patterns are generated from NiO NP thin films by a vacuum-free, lithography-free, and solution-processable route. In particular, a continuous wave laser is used for the LDW reductive sintering of the metal oxide under ambient conditions with the aid of reducing agents in the ink solvent. Thin (∼ 40 nm) Ni electrodes of glossy metallic surfaces with smooth morphology and excellent edge definition can be fabricated. By applying this method, we demonstrate a high transmittance (>87%), electrically conducting panel for a touch screen panel application. The resistivity of the Ni electrode is less than an order of magnitude higher compared to that of the bulk Ni. Mechanical bending test, tape-pull test, and ultrasonic bath test confirm the robust adhesion of the electrodes on glass and polymer substrates.
authors.affiliation: Laser Thermal Laboratory, Department of Mechanical Engineering, University of California , Berkeley, California 94720-1740, United States.
authors.forename: Daeho
authors.initials: D
authors.lastname: Lee
authors.forename: Dongwoo
authors.initials: D
authors.lastname: Paeng
authors.forename: Hee K
authors.initials: HK
authors.lastname: Park
authors.forename: Costas P
authors.initials: CP
authors.lastname: Grigoropoulos
keywords: Ni electrode; NiO nanoparticle ink; flexible substrate; selective laser reductive sintering; solution-processable route; touch screen panel