A layer-by-layer green inkjet printing methodology for developing indium tin oxide (ITO)-based transparent and conductive nanofilms

A facile, cost-effective, and green inkjet printing methodology is proposed for the fabrication of a transparent and conductive nanostructured indium tin oxide (ITO) thin films. Unlike solution deposition methods, the ITO nanoparticles did not deposit herein on the substrate. Instead, they are formed in-situ during the inkjet printing. The layer-by-layer inkjet printing is conducted stepwise, by printing the indium acetate based ink on a glass substrate, then printing the tin acetate-based inkjet ink onto a dry previously printed layer. Next, heat treatment is carried out leading to the formation of nanostructured ITO thin film. The resulting inkjet-printed sustainable transparent three-layer thin films were characteristic of evenly dispersed ITO nanodomains taking the advantage of appropriate wettability and rheological properties of the engineered ink solution. Surprisingly, the electrical resistivity of thin film drastically dropped (874 times) from 43.72 Ω cm for one-layer (48 nm thickness) to 0.05 Ω cm for three-layer (154 nm thickness) thin films, without sensible drop in optical properties (from 88% to 84% in the same order). In view of sustainability, i.e. low-cost clean inkjet printing, green chemicals used, and water-based synthesis, this novel technique opens new avenues for developing sustainable transparent thin films with superior electrical conductivity.