Scientists unravel the mysteries of irreversibility in electrochromic thin films

Tungsten oxide, an electrochromic (EC) material with immense potential for technical applications such as in smart windows, has attracted much interest for its energy-saving qualities. However, after multiple cycles, such EC devices exhibit degradation in optical modulation and reversibility owing to lithium-ion trapping. Now, scientists have adopted a quantitative approach to understand the irreversibility of lithium intercalated tungsten oxide films, laying the groundwork for developing superior electrochromic materials and devices.