Realization of transparent conducting networks with high uniformity by spray deposition on flexible substrates

Optimization of the spreading and the evaporation behaviors of atomized coating solutions on a substrate is essential for achieving highly uniform network thin films of single-walled carbon nanotubes (SWCNTs) and silver nanowires (AgNWs) on plastic substrates by the spray coating method. We have demonstrated that efficient control of the surface energy of the substrate and the spray coating parameters improves the opto-electrical performance and the uniformity of the network thin film based on the characteristics of the coating solutions. In terms of network formation, the surfactant-assisted aqueous SWCNT dispersion was less sensitive to the surface tension of the substrate than the almost pure aqueous AgNW solution. In addition, the solution containing the AgNWs has to be highly atomized by increasing the gas flow rate to effectively scatter the nanowires on the surface, as the AgNW solution exhibits a high contact angle on hydrophobic substrates. Finally, UV/ozone irradiation of the substrates and deposition of atomically thin and transparent graphene oxide nanosheets on the network thin films enhanced the conductivity and the electrical uniformity of the spray-coated network films.