In this study, we developed a roll-to-roll Ag electroplating process for metallic nanowire electrodes using a galvanostatic mode. Electroplating is a low-cost and facile method for deposition of metal onto a target surface with precise control of both the composition and the thickness. Metallic nanowire networks [silver nanowires (AgNWs) and copper nanowires (CuNWs)] coated onto a polyethylene terephthalate (PET) film were immersed directly in an electroplating bath containing AgNO3. Solvated silver ions (Ag+ ions) were deposited onto the nanowire surface through application of a constant current via an external circuit between the nanowire networks (cathode) and a Ag plate (anode). The amount of electroplated Ag was systematically controlled by changing both the applied current density and the electroplating time, which enabled precise control of the sheet resistance and optical transmittance of the metallic nanowire networks. The optimized Ag-electroplated AgNW (Ag-AgNW) films exhibited a sheet resistance of ∼19 Ω/sq at an optical transmittance of 90% (550 nm). A transmission electron microscopy study confirmed that Ag grew epitaxially on the AgNW surface, but a polycrystalline Ag structure was formed on the CuNW surface. The Ag-electroplated metallic nanowire electrodes were successfully applied to various electronic devices such as organic light-emitting diodes, triboelectric nanogenerators, and a resistive touch panel. The proposed roll-to-roll Ag electroplating process provides a simple, low-cost, and scalable method for the fabrication of enhanced transparent conductive electrode materials for next-generation electronic devices.
Keywords: electroplating; epitaxial growth; roll-to-roll; silver nanowire; transparent electrode.