Anti-reflective optical coatings incorporating nanoparticles

Abstract

This paper presents a simple approach for forming anti-reflective film stacks on plasticsubstrates employing aqueous colloidal dispersions of metal oxide nanoparticles. Resultsdemonstrate that it is possible to fabricate a polymeric thin film of continuously tunablerefractive index over a wide range by loading the film with varying concentrationsof metal oxide nanoparticles. Specifically, the refractive index for the polymerfilm was tuned from 1.46 to 1.54 using silica nanoparticle loadings from 50 to0 wt% and from 1.54 to 1.95 using ceria nanoparticle loadings from 0 to 90 wt%,respectively. The low and high refractive index layers are then combined to create ananti-reflective coating which exhibits a reflectance spectrum, abrasion resistance, haze andtransmission values that compare well with those produced using state-of-the-art vacuumbased techniques. Furthermore, the results show that it is possible to begin withaqueous dispersions and then dilute them with organic solvents for use in a spincoating method to prepare the polymer–metal oxide nanoparticle composite films.