Electrochromic WO₃ Thin Films: Preparation by Nanocrystalloid Liquid Phase Coating and Performance Optimization

Electrochromic materials have been applied in energy-saving buildings, intelligent displays, and other fields, recognized as one of the most promising intelligent materials for research. Liquid phase method for preparation of WO3 electrochromic thin filmscan construct complex polychromies structures, showing great potential in modulation amplitude and short response time, especially in large area and low cost preparation. This study aims to develop a low-cost, easy-to-scale WO3 nanocrystalline liquid phase coating process, and improve cycle stability and preparation process. WO3 electrochromic films with high modulation amplitude, rapid response and fatigue resistance were prepared. Optimized the annealing process, WO3 nanopowders were synthesized with low aggregation and high crystallinity, and then WO3 nanocrystalline coating solution was prepared by ball milling dispersion. Thin film microstructure and coating solution crystallinity were optimized. The obtained thin electrochromic films of WO3 show high tuning amplitude (82%), short response time (t(c)/t(b): 8 s/4.2 s), high colouring efficiency (81.5 cm(2)center dot C-1), and high cycling stability (> 1000 times). In this work, the crystallization and dispersion properties of WO3 nano-powder were modified to comprehensively improve the performance of WO3 electrochromic films prepared by nanocrystalline liquid phase coating technology. All results above demonstrate that the WO3 electrochromic film prepared by the liquid phase method is expected to be used in the future with high color-changing performance and cycle stability.