Inverse Nanocomposites Based on Indium Tin Oxide for Display Applications: Improved Electrical Conductivity via Polymer Addition

A new method for the preparation of electrically conductive nanoparticle-polymer composite (NPC) films is shown in this work. These films are intended to be applied in displays. Thin layers of percolating nanoparticles in an organic polymer matrix are presented. First, a nanoparticle scaffold with high porosity is prepared. Subsequently, it is infiltrated with a monomer, which is finally polymerized. The formed composite is called an inverse nanocomposite, as the continuous percolating nanoparticle scaffold is formed first and mainly preserved during the whole process. Indium tin oxide (ITO) nanoparticles obtained from flame spray pyrolysis (FSP) are laminated onto a substrate. These porous scaffolds are infiltrated using liquid 1,6-hexanediol diacrylate (HDDA) as monomer. Restructuring of the particle network during the liquid imbibition caused by capillary forces leads to an increased electrical conductivity upon addition of the insulating organic monomer. A further and even stronger increase in the electrical conductivity was achieved after UV-curing of the HDDA-filled nanoparticle films, which is explained by the shrinkage forces of the organic phase during polymerization. With this new method, electrically conductive thin films for optoelectronical applications with almost the conductivity of pure ITO coatings can be produced.