Polypyridyl Metallo-Organic Assemblies for Electrochromic Applications

Electrochromic films undergo optical changes in response to a redox stimulus. This intriguing phenomenon can be used for a wide range of applications, including smart windows, sensors, color displays, and memory elements. Despite the rapid progress of late, designing suitable electrochromic materials that offer low-cost production, appealing colors, and pronounced optical contrast with high efficiency, as well as long-term stability remains an engineering challenge. Solid-state metal oxides, liquid crystals, and organic polymers have been for many years the leading candidates, successfully making their way into commercial products. An alternative class of materials relies on metal complexes that can be processed from solution, offer a variety of colors, and have metal-centered stable and reversible redox chemistry. These metallo-organic materials possess a full range of electrochromic properties, including ultrahigh coloration efficiencies, and cyclic stability. Here, some of the recent scientific developments in this field are highlighted.