Photochromic Coatings Containing Ag(Cl1− x Br x ) Microcrystals

Abstract

Photochromic ormosil coatings containing Ag(Cl1−xBrx) microcrystals were formed on a glass substrate via the sol-gel process. Methyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane were used as starting materials of the ormosil matrices. 3-chloropropyltrimethoxysilane and bromophenyltrimethoxysilane were added as halogen sources and silver colloidal dispersion was introduced into the precursor sol. The coated glass became transparent and photosensitive after Ag(Cl1−xBrx) microcrystals were precipitated in the coatings above 300°C. Insertion of a SiO2 buffer layer between the substrate and photochromic layer was effective in preventing Ag+ migration into the substrate. Photochromic performances were improved by the substitution of Cl with Br and the incorporation of a minute amount of Cu.