Sol-gel/rhodamine 6G composite films with tailored microstructures

摘要

A multi-step hydrolysis procedure was developed to prepare composite organic dye/sol-gel thin films with variable porosity for such applications as switches or sensors. Variation of acid and base catalyzed hydrolysis sequences of three sols prepared from tetraethoxysilane with identical H$-2$/O/Si ratios, dilution factors, and pH resulted in considerably different silicate speciation. Under conditions where monomer was avoided, the refractive indices of as-deposited films could be varied by an aging step prior to film deposition. This general strategy, which relies on the aggregation of fractal polymeric clusters, is compatible with the low temperature and near neutral pH requirements of both organic dyes and biologically-active species such as enzymes.