Rejuvenation of Electrochromic Devices

Electrochromic devices (ECDs) are a hot pot due to their significant energy‐saving effect in green buildings. However, the ECDs suffer from degradation induced by ion trapping during cycling, which restricts their further development. Here, it is demonstrated that the electrochromic performance of the degraded ECDs can be rejuvenated by heat treatment method The release mechanism of trapped ions in films is simulated and validated using three types of ECDs. The semi‐solid‐state ECD evinces a state of near‐failure at low temperatures can regain its initial performance by heating. All‐solid‐state ECDs, including amorphous WO3 (a‐WO3 ECD) and crystalline WO3 (c‐WO3 ECD) as the electrochromic layer, can also release the trapped ions and regain the performance (97.3% and 95.5% of initial optical modulation) by annealing, regardless of the way of degradation. The research has extended the lifespan of multiple ECDs, providing significant practical value and promoting sustainable, and eco‐friendly development. During the cycling process, due to the capture of ions by the electrochromic layer, the optical modulation range of the electrochromic device (ECD) significantly decreases. But after heat treatment, the captured ions gain energy and become free ions again, and the performance of the ECD returns to same level as the initial performance.