Absorption Bands of Electrochemically-Colored Films of WO₃, MoO₃ and Mo_cW_1-cO₃

Abstract

Optical absorption bands of electrochemically-colored films of amorphous WO 3 , MoO 3 and Mo c W 1- c O 3 were investigated. The peak photon energy of the bands depends not only on the amount of injected charges but also on the Mo content. In the WO 3 films, the absorption band originates from the intervalence trasfer of electrons. In MoO 3 and mixed films, however, the absorption bands are considered to consist of two different components. The first is the intervalence trasfer band and the second is a component of absorption at higher energies. The second component is considered to be related to Mo atoms. The area under the absorption curve increases linearly with increasing density of injected charges in the WO 3 film. In the film with large c , the absorption tends to saturate.