Enhanced diffusion through porous nanoparticle optical multilayers

Herein we demonstrate improved mass transport through nanoparticle one-dimensional photonic crystals of enhanced porosity. Analysis is made by impedance spectroscopy using iodine and ionic liquid based electrolytes and shows that newly created large pores and increased porosity improve the diffusion of species through the photonic crystal. This achievement is based on the use of a polymeric porogen (polyethylene glycol), which is mixed with the precursor suspensions used for the deposition of nanoparticle TiO ₂ and SiO ₂ layers and then eliminated to generate a more open interconnected void network, as confirmed by specular reflectance porosimetry. A compromise between pore size and optical quality of these periodic structures is found.