Fabricating Electrochromic Thin Films Based on Metallo-Polymers Using Layer-by-Layer Self-Assembly: An Attractive Laboratory Experiment

Metallo-supramolecular polyelectrolytes (MEPE) based on iron(II) -acetate and 1,4-bis(2,2':6',2 ''-terpyridin-4'-yebenzene are assembled by layer-by-layer deposition on transparent electrode surfaces. When a potential is applied, the color of the film can be switched from blue to transparent. Due to the strong absorption and the fast switching speed, the color change is readily observed with the eye. The device shows reversible switching and long-term stability. The experiment demonstrates the basic concept of electrochromic windows, an upcoming technology.