Ion transport in electrochromic nickel oxide thin films

Dynamic process of ion injection into nickel oxide film in both KOH and LiClO4–PC electrolyte were studied using electrochemical measurement. Cottrell and Butler–Volmer current–time relations were applied to obtain ion diffusion coefficient D and exchange current Iex by fitting the experimental data. Results showed that the film displays complex transport behavior which depends on the deposition rate of the film, the environment and sequence of heat treatment, the adopted electrolyte. The change of the number of the oxygen and nickel vacancies are suggested to be responsible for the phenomena.