High-performance ITO-free electrochromic films based on bi-functional stacked WO3/Ag/WO3 structures

Stacked WO3/Ag/WO3 (WAW) films were employed as both transparent electrodes and electrochromic materials. These nontoxic, low-cost WAW films that were prepared at room temperature exhibited not only low sheet resistance (12.2 Omega/rectangle) and high transmittance ( > 80%) but also compelling electrochromic performance with high optical contrast (53%) at 650 am, long-term cycling stability (3000 cycles), and short switching time (coloration time = 11 s; bleaching time = 10.5 s). The coloration efficiency of the WAW films was 136 cm(2) C-1, which is higher than those of most electrochromic transition metal oxides. In addition, by utilizing such bi-functional films, the flexible electrochromic film with acceptable performance was obtained. (C) 2015 Elsevier B.V. All rights reserved.