Characterization of nano-structured thin films of electrodeposited Ce–Co mixed oxides for EC devices

Composite films of Ce–Co oxides were deposited on ITO-coated glass using electrochemical deposition in aqueous solutions containing cerium and cobalt nitrates with various molar ratios (Ce/Co). Films deposited in equimolar mixture gave highest transmittance and little spectral change during charging and discharging processes in 0.05 M NaOH solution. They have also large charge capacity in the potential range from −900 to 600 mV vs. Ag. The TEM observations and EDS measurements of the Ce–Co composite films revealed that they consist of CeO2 nano-crystals in amorphous host structures. It was concluded that these Ce–Co composite films (Ce/Co=1.0) are most suitable for transparent counter electrodes in electrochromic (EC) devices.