Bipyridinium salt solutions

Abstract

The present invention provides solutions of certain 4,4'-bipyridinium salts, such as salts of 1,1'- dibenzyl-2,2',6,6'-tetraalkyl-4,4'-bipyridinium cations. The solutions of the invention are employed as solutions of variable transmittance in solution-phase electrochromic devices, including such devices that are single-compartment and self-erasing. In the solutions of the invention in such devices, the bipyridinium salts are cathodic electrochromic compounds, as reduction of a cation of such a salt causes its molar extinction coefficient at at least one wavelength in the visible range to increase markedly. Electrochromic devices, in which solutions of the invention provide variable transmittance, are, in turn, components of variable transmittance in display devices, windows and other types of light filters, and variable reflectance mirrors, such as those that can be used as dimmable rearview mirrors in motor vehicles.

Dependencies are inferred from the claim text.