Enhanced electrochromic properties of self-organized nanoporous WO3

Self-organized nanoporous layers of WO3 were grown by anodization, and their electrochemical and electrochromic properties were investigated and compared to compact anodic layers. As-formed WO3 layers had an amorphous structure but could be transferred to a monoclinic structure by thermal annealing treatment. Compared to the compact layer, the nanoporous WO3 layer showed strongly enhanced ion intercalation capacity with reversible characteristics during electrochemical cycling processes. The nanoporous structures showed a significantly enhanced electrochromic contrast, faster switching response, and less sensitivity to intercalation loss by crystallization.