Highly reliable copper nanowire electrode with enhanced transmittance and robustness for organic light emitting diodes

Abstract A highly conductive and robust copper nanowire (CuNW) composite film is fabricated through a simple welding and reduction process. The nanowires are welded to a unit and reduced into pure metal copper without oxide layer on the surface by poly(ethylene glycol) (PEG). The electrical conductivity of the film significantly increases and the film's surface roughness decreases greatly since the wire junctions are well welded. When the polymethyl methacrylate (PMMA) is coated on the CuNWs as a protecting layer, the nanowires are tightly bonds to the substrate, and the transmittance of the film increases dramatically. The whole process can be accomplished within 10 min and the obtained film shows a low sheet resistance of 22 Ω/sq with a transmittance of 88%, which is among the top values to the best of our knowledge. This obtained CuNW/PMMA composite film can resist air, water and ethanol exposure without obviously conductivity deterioration. With this CuNW/PMMA composite film as anode for the organic light-emitting diode, the device shows better performance than that with ITO anode.