Electrochromic materials and devices: Brief survey and new data on optical absorption in tungsten oxide and nickel oxide films

Current work on inorganic electrochromic materials and devices is reviewed briefly, and the emphasis on thin films of W oxide and Ni oxide is pointed out. New results are presented on the optical properties for sputter-deposited thin films of these two materials: for Li+ intercalated sub-stoichiometric W oxide, it is shown that the absorption can be reconciled with an extended “site saturation” model accounting for electronic transitions between W ions in 6+, 5+, and 4+ states, and for H+ deintercalated Ni oxide, it is found that the coloration efficiency is higher than in prior work presumably as a consequence of the nanocrystalline structure ensuing from the deposition conditions.