Tungsten oxide, nickel oxide and Prussian blue (PB) are widely investigated inorganic electrochromic materials. We have synthesized a series of nanostructured electrochromic films by wet chemical processes, including PB, NiMoO₄, Nb₁₈W₁₆O₉₃ and WO₃∙xH₂O films. These films exhibit enhanced optical modulation, switching response, and coloration efficiency, showing promising potential for high-performance smart windows and displays. 
Recent studies have further advanced electrochromic devices toward multifunctional and intelligent regulation. Multi-band and multi-state electrochromic regulations have been achieved through cation–anion co-intercalation and independent control of visible (VIS) and near-infrared (NIR) transmittance [1,2]. Additionally, hydrogel electrolytes based on polyacrylamide (PAM), poly(N,N-dimethylacrylamide) (PDMA), polyzwitterionic sulfobetaine, poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA), and PAA/PAM/hypromellose (PAA-PAM-HPMC) have been developed for electrochromic devices. These electrochromic devices exhibit large optical modulations, fast coloration/bleaching responses, and excellent cycling stability (retaining 96.1% of the initial optical modulation after 34,000 cycles) [3]. Wide-temperature operation from −20 to 60 °C has also been demonstrated [4], highlighting the potential of hydrogel electrolytes for fast-response, durable, and high-performance electrochromic smart windows.

References
[1] J. Sun, Z. Chen, R. Zhang, M. Yin, Y. Zhu, J. Hu, Q. Zhou, P. Shao, Q. Huang, D. Ma, R.-T. Wen, J. Wang, Nat. Commun., 2025, 16, 6993.
[2] D. Ma, T. Yang, X. Feng, P. Wang, J. Huang, J. Wang, H. Li, Adv. Sci., 2024, 11, 2307223.
[3] X. Li, H. Cai, Y. Zhou, D. Ma, J. Wang, Sol. Energy Mater. Sol. Cells, 2026, 303, 114392.
[4] Q. Li, J. Li, W. Wang, D. Ma, G. Li, J. Wang, Adv. Funct. Mater., 2025, 35, 2415874.

electrochromic device; solid electrolyte interphase; interface engineering; quasi solid state electrolyte; long cycling stability