Electrochromic properties of three-colour prussian green ECDs and the evolution of Fe ions during the discoloration process

• Published in: Materials letters 2022-03, Vol.311, p.131627, Article 131627
• Main Authors: Wang, Y.G., Wang, M., Wang, Y.Q., Zhang, Q., Zhou, H.N., Zhao, H.L.
• Format: Article
• Language: English
• Subjects: Color; Discoloration; Electrochromic cells; Electrochromic devices; Electrochromism; Evolution; Iron; Materials science; Optical materials and properties; Photoelectrons; Pigments; Prussian green; Thin films
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2021.131627

•Prussian green ECD was prepared by one-step hydrothermal method.•ECDs can show three color conversions with a single layer electrochromic material.•More active sites and shorter K+ diffusion distance improve the performance of ECDs.•The evolution of Fe in the process of discoloration has been systematically studied.•The color of the film depends on the ratio of Fe3+/Fe2+ in the PB structure. Prussian green (PG) film was directly grown on FTO glass by one-step hydrothermal process for excellent electrochromic performance. The electrochromic devices (ECDs) based on as-grown PG film can show reversible color changes between green, blue and colorless states. The existence state of iron elemental in PG film at different color states was studied by X-ray photoelectron spectroscopy. Compared with the traditional Prussian blue ECDs, PG ECDs achieve a higher optical modulation range (42.7%) and a shorter switching time (tc/tb=1.0/7.4 s). This study provides a novel method for preparing high-performance three-color ECDs by a simple hydrothermal method, and clearly shows the evolution of Fe ions during the discoloration process.