Theoretical and experimental results on Au–NiO and Au–CoO electrochromic composite films

This paper reports on the theoretical calculations and experimental results on the optical properties, between 400 and 1000 nm, of Au–NiO and Au–CoO composite films. The calculations were based on the Maxwell Garnett effective medium theory, with Au fill factors f varying from 0.0 to 0.05. The results for both media are very similar. The Au configuration in the insulating matrix was modeled to be isolated single spheres (ISS), single linear chain (SLC) and fcc cluster (FCC), as examples of selective absorption in these composite films. Variations in transmission and reflection can be obtained either by thickness variation, as well as from Au incorporation, as seen from theoretical and experimental results. Au–NiO films with different reflected colors (blue, green, yellow and orange-red) and same Au content were obtained by varying the pressure inside the sputtering deposition chamber. Green colored Au–CoO films with different Au content were deposited.