In-situ IR and UV-V spectroelectrochemistry of prussian blue analogues:: Cupric hexacyanoferrate

Cupric hexacyanoferrate films, prepared by a simple coating method, were characterized by coupling electrochemical and in-situ optical measurements. Time resolved UV-Vis spectroscopy showed a fast oxidation of the redox centers, 350 ms switching time, arising from the reversible oxidation of Fe(II) to Fe(III). The relative amount of active redox centers grows as the film thickens whereas the quantity of inactive material seems to be roughly constant and linked to the surface microstructure of the underlying Cu electrode. Non-active centers seem to have a cyanide environment similar to that of the redox centers in the reduced state. Fast color switching and cycling stability are features that make these films promising for applications in electrochromic devices and photoimage formation.