Programmable refractive index of nanoporous organosilicate films through microsphere masking and sacrificial polymer mediated assembly

摘要

We present our preliminary results on experimentation towards designing thin nanoparticle films with programmable refractive indices controlled by amorphous packing density of particles. A sacrificial polymer approach is used with substrate surface energy controlling the wetting of the polymer. Thus the local packing density, and consequentially the refractive index, is controlled by the surface energy of the substrate. Through the use of microsphere lithography and plasma induced isotropic mask shrinking, high and low surface energy regions are patterned on a sub-micron scale. With feature sizes this small, the flow of both the particles and the sacrificial polymer between high and low surface energy regions is overlapped. This creates a film with refractive index proportional to the fractional coverage of high and low surface