Roll-to-roll preparation of silver-nanowire transparent electrode and its application to large-area organic light-emitting diodes

Silver-nanowires (AgNWs) transparent electrodes were successfully fabricated on a polyethylene terephthalate (PET) film substrate by roll-to-roll processes. The AgNWs were embedded in a polymer resin so that the surface was flat enough to fabricate organic light-emitting diodes (OLEDs) without an additional surface planarization. For the fabrication of the embedded AgNWs electrodes, a polyimide film was utilized as an AgNWs-carrying film to realize a roll-to-roll process for the first time. Large-area OLEDs were then deposited directly on the embedded AgNWs electrodes by a roll-to-roll vacuum deposition process. The OLEDs with the embedded AgNWs electrodes on a PET film showed 30–40% better performance than those with commercial indium-tin-oxide electrodes on glass substrates. The surface roughness, sheet resistance, and optical transmittance of the embedded AgNWs electrodes on a PET film were around 3 nm, 5 Ω/square, and 85%, respectively. The sheet-resistance uniformity of the embedded AgNWs electrode was higher than 90% in 15 cm × 45 cm area.