Oxidation suppression of copper nanowire percolation network in ambient condition by ultrafast plasmonic laser nanowelding for flexible transparent conductor

Abstract

Compared with silver nanowire which is not so sensitive to oxidation problem but very expensive, the use of very cheap and highly conductive copper nanowire for percolation network transparent conductor has been very much limited in ambient condition due to the severe oxidation during the conventional thermal annealing process. In this study, we introduce a facile ultrafast laser nanowelding process using plasmonic effect at nanowire junction to suppress oxidation and successfully fabricate copper nanowire based percolation network conductor without any inert novel gas or vacuum environment. Due to the low temperature and fast process nature, plasmonic laser nanowelding could form copper nanowire network on heat sensitive flexible or even stretchable substrates. Through the ultrafast thermal treatment by plasmonic laser nanowelding, copper nanowire percolation network could demonstrate (1) transparent conductors with high transmittance, low sheet resistance for touch panel, and (2) highly stretchable conductors with superior mechanical reliability, which are almost impossible to achieve by conventional bulk thermal treatment.