Facile preparation of a visible- and near-infrared-active electrochromic film by direct deposition of a ruthenium dioxolene complex on an ITO/glass surface

An electrochromic film was prepared by simple evaporation of a solution of a ruthenium-dioxolene dye on an ITO/glass surface to give a mechanically attached layer, without the need for special anchoring groups or polymerisation to achieve surface attachment. Using an aqueous solvent/electrolyte system, in which the microcrystalline dye is insoluble, reversible electrochemical behaviour is observed leading to substantial changes in absorbance in the visible and near-infrared regions. Alternation of the applied potential resulted in rapid (≈0.1-1 s timescale) on/off switching of NIR absorbance at 1300 nm which persisted over thousands of cycles with minimal degradation.