Transparent, inorganic-organic thick films by electrophoretic sol-gel deposition using polysilsesquioxane particles

摘要

Transparent, inorganic-organic thick films of a few micrometers in thickness have been prepared on glass substrates coated with indium tin oxide (ITO) by constant-voltage electrophoretic sol-gel deposition method using polysilsesquioxane particles such as polyphenylsilsesquioxane (PhSiO_(3/2)) and polybenzylsilsesquioxane (BnSiO_(3/2)). The films composed of aggregates of PhSiO_(3/2) and BnSiO_(3/2) particles became transparent with morphological changes from aggregates of particles to a monolithic, continuous layer with high refractive indices after heat treatment. The increases in optical transmittance was caused by thermal sintering of the particles in the films. Thermal sintering of PhSiO_(3/2) particles at 140 °C and that of BnSiO_(3/2) particles at 50 °C reduced the interfaces and openings among the particles and decreased light scattering of the films to form transparent films. The thermal sintering of the PhSiO_(3/2) and BnSiO_(3/2) particles was caused by the decrease of viscosity at temperatures higher than the glass transition temperatures.