Versatile electrochromic displays based on TiO2 nanoporous films modified with triruthenium clusters

We report a new versatile electrochromic device based on nanocrystalline titanium dioxide films modified with triruthenium acetate clusters of the type [Ru3O(OOCCH3)6(py)2(BPEB)]PF6 (BPEB = 1,4-bis[2(4-pyridyl)etenyl]benzene). As evaluated from cyclic voltammetry and spectroelectrochemistry, the most relevant electrochromic process in this system is associated with the first reduction of the [Ru3O] cluster core. Typical electrochromic response is observed within a millisecond time scale, covering a wide range optical window (up to 1100 nm), and exhibiting excellent stability over a thousand cycles between 0.5 and −1.0 V.