Room-Temperature Nanowelding of a Silver Nanowire Network Triggered by Hydrogen Chloride Vapor for Flexible Transparent Conductive Films

High contact resistance between silver nano wires (AgNWs) is a key issue in widespread application of AgNW flexible transparent conductive films as a promising candidate to replace the brittle and expensive indium tin oxide. A facile, room-temperature nanowelding method of an AgNW network triggered by hydrogen chloride (HCI) vapor is demonstrated to reduce the sheet resistance of the AgNW, network. Under the visible light, O-2 and HCl vapor serving as an etching couple induced silver atoms to be transferred from the bottom AgNW at the junction to the top one, and then, these silver atoms epitaxially recrystallized at the contact position with the lattice of the top AgNW as the template, ultimately resulting in the coalescence of the junction between AgNWs. Polydimethylsiloxane (PDMS) was spin-coated onto the HCl-vapor-treated (HVT) AgNW network on the polyethylene terephthalate substrate to fabricate PDMS/HVT AgNW films. The fabricated film with low sheet resistance and high transmittance retained its conductivity after 4000 bending cycles. Furthermore, excellent heating performance, electromagnetic interference shielding effectiveness, and foldability were obtained in the PDMS/HVT AgNW film. Thus, the role of the simple nanowelding process is evident in enhancing the performance of AgNW transparent conductive films for emerging soft optoelectronic applications.