Preparation of Monodispersed Nanoparticles of Transparent Conductive Oxides

Generally, indium-tin-oxides (ITO) thin film is prepared by the sputtering process with ITO target, but only 20 % of ITO yielded from the target is deposited on the substrate. Namely, about 80 % ITO is exhausted by the deposition elsewhere far from the substrate. The recycling process of indium is limited so that ca. 20 % ITO of the starting material is lost without any recovery. Even if the recycling of ITO has been carried out in this process, we should prepare ITO target of 5 times more than apparent use of ITO on film. If we change it to printing process from the sputtering, the reduction in ITO use is expected as ca. 50 %, considering the increase in film thickness by printing. Our target technology also includes ITO nanoink for the project. As a result, monodispersed ITO nanoparticles (NPs) with a cubic shape were fabricated by using quaternary ammonium hydroxide-assisted metal hydroxide organogels. These NPs have perfect uniformity in size with beautiful shape, and perfect single crystalline structure including Sn. As we were attempted to make thin film with ITO nanoink, it was successfully fabricated below 200 nm in thickness and the resistivity was drastically decreased below 1.0 × 10−3 Ω cm after heat treatments. GZO nanoink as substitute of ITO has also been developed.