Dependence of WO 3 Electrochromic Absorption on Crystallinity

The optical absorption of amorphous electrochromic display layers is explained as small polaron absorption. The necessary W 5+ 5d‐electron localization is favored by the lattice disorder. This is concluded from the change of the optical properties to free‐electron‐like behavior upon crystallization of the layers. The increased electrocoloration stability of amorphous layers and the blue shift of the absorption peak in Mo‐doped films can also be explained within the model given.