Researchers from the Universidad Publica de Navarra in Spain and from Virginia Polytechnic Institute and NanoSonic Inc., both in Blacksburg, have shown that an electrostatic self-assembled monolayer process can create multilayered thin-film materials with a controlled refractive index.

The process involves depositing alternating positively and negatively charged layers on an ionized substrate, thus providing electrodynamically determined order at a molecular level. The method, published in the December issue of IEEE Photonics Technology Letters, could be applicable to a variety of diverse substrates, such as ceramics, metals and polymers, with different shapes and forms.

During test trials, the researchers formed multiple structure combinations of a cationic electrolyte formed from poly(diallyldimethyl ammonium chloride) and anionic electrolytes formed from poly(sodium 4-styrene-sulfonate) salt and a polymer dye. The trials produced films with a real refractive index that was controlled from 1.424 to 1.615 at a wavelength of 550 nm.