Long life all-solid-state electrochromic devices by annealing

Annealing temperature has a significant influence on the performances of the electrochromic films and devices, such as optical transmittance modulation, response time and cyclic stability. Although there are lots of reports on the effect of annealing temperature on the performance of monolayer, the relationship between annealing temperature and electrochromic devices (ECDs) is rarely studied. Here, all-solid-state ECDs glass/ITO/NiO/ZrO2/Li/WO3/ITO are prepared by evaporation method and annealed at different temperature from 200 °C to 400 °C. The results show that the cyclic stability of the ECDs has a strong association with the annealing temperature. The ECDs annealed at low temperature suffer from poor cyclic stability because of the irreversible insertion of Li ions in WO3 layer. The ECD annealed at 400 °C exhibits superior stability with high optical modulation of 50.2% even after 50000 cycles at wavelength of 400–1050 nm. The influence mechanism of annealing temperature on the ECDs is analyzed which has great value for practical application.