Abstract
The degradation of electrochromism in amorphous WO3-TiO2 films prepared by electron-beam deposition have been studied and the lifetime of the WO3-TiO2 films was found to be five times greater than that of the WO3 films. X-ray diffraction revealed that the crystal structure of the WO3-TiO2 films was still amorphous after the coloring and bleaching cycles, while a crystalline peak was observed in the amorphous WO3 films SIMS analysis revealed that lithium accumulated in the WO3 films, but not in the WO3-TiO2 films. The X-ray diffraction and XPS analysis revealed that the as-deposited WO3-TiO2 films were of an amorphous network structure based on the WO3 which has slightly shorter bonds length and that the WO3-TiO2 films are stable against the crystallization by annealing.
From these results, the WO3-TiO2 films have a small number of defect bonds that act as trapping sites for lithium. We conclude that the prolonged lifetime of electrochromism in WO3-TiO2 films is the result of reduced accumulation of lithium in the films.
