Preparation of a Photochromic Glass Doped with Methylviologen Radical Cation via a Sol-Gel Process

Methylviologen cation radical is produced by photolysis of methyl viologen dichloride entrapped in a sol-gel glass. The sol-gel glass is shown to be microporous, and it is suggested that the microporosity prevents oxygen diffusion thereby helping to extend the lifetime of the cation radical to a period of months. Initial losses of a substantial fraction of the charge separation are not observed. These results bear directly on efficient photochemical energy storage.