Reversible Zn2+ Insertion in Tungsten Ion-Activated Titanium Dioxide Nanocrystals for Electrochromic Windows

Zinc-anode-based electrochromic devices (ZECDs) are emerging as the next-generation energy-efficient transparent electronics. We report anatase W-doped TiO₂ nanocrystals (NCs) as a Zn²⁺ active electrochromic material. It demonstrates that the W doping in TiO₂ highly reduces the Zn²⁺ intercalation energy, thus triggering the electrochromism. The prototype ZECDs based on W-doped TiO₂ NCs deliver a high optical modulation (66% at 550 nm), fast spectral response times (9/2.7 s at 550 nm for coloration/bleaching), and good electrochemical stability (8.2% optical modulation loss after 1000 cycles).