Colloidal indium tin oxide nanoparticles for transparent and conductive films

Nanosized colloidal indium tin oxide (ITO) dispersion was prepared for electrically conductive and transparent coating materials. A titanate coupling agent, isopropyl tri(N-ethylenediamino)ethyl titanate, was chosen as a dispersant for the stabilization of ITO nanoparticles in organic solvent. ITO sol was deposited on a cathode ray tube panel for antistatic or electromagnetic shielding purposes, and alkyl silicate was used for the formation of an antireflective over-coat layer. The resulting double-layered coating showed low sheet resistance, which satisfied semi-TCO regulation and low reflectance of visible light. To control the electrical and optical properties of the coating layer, the effects of secondary particle size of ITO aggregates and the dispersant concentration of ITO sol were studied. The stability of ITO sol was estimated by measuring the particle size as a function of the storage days and the aggregation of colloidal ITO dispersion with storage day was explained by depletion flocculation.