Facile synthesis of hybrid WO3/MoOx electrochromic films for application in complementary electrochromic devices

In this study, WO3 nanoparticles and MoO3 nanoribbons were prepared using a microwave-assisted hydrothermal method. Following a grinding treatment, a stable WO3/MoO3 suspension having a nanoheterojunction structure was obtained. Moreover, oxygen vacancies were introduced in the MoO3 nanoribbons (MoOx) during the grinding process. Consequently, the ground WO3/MoOx composite film exhibited an enhanced electrochromic (EC) performance compared to the ground WO3 and MoO3 films not only due to its favorable morphology for ion transport but also the enhanced intervalence electron transfer. To further evaluate the potential of ground WO3/MoOx electrodes for practical applications, a complementary electrochromic device (ECD) was constructed using ground WO3/MoOx and polyaniline:poly(4-styrenesulfonate) (PANI:PSS) as cathodic and anodic coloring materials, respectively. This complementary ECD yielded a transmittance modulation of 55.4% at 650 nm with rapid switching times of 7.4 s (bleaching) and 3.6 s (coloring). The ECD also exhibited a high coloration efficiency of 154 cm2/C and a high cycling stability with an 80.6% transmittance retention after 2000 cycles. These results demonstrate that ground WO3/MoOx composites are attractive materials for fabricating high-performance ECDs.