Prussian blue analogues have attracted significant attention as low-cost electrochromic materials with facile synthesis and stable redox behavior. However, their ion transport limitation impact practical application. To overcome the limitation, in this work a hydrothermal ion exchange strategy is proposed, in which carbon dots are employed as ion carriers. During the hydrothermal process, metal ions carried by the carbon dots in situ replace Fe ions in the Prussian blue films, leading to the formation of Prussian blue analogues films. As the hydrothermal reaction proceeds, carbon dots grow on the surface of the Prussian blue analogues films, yielding a new type of carbon dots/ Prussian blue analogues electrochromic hybrid film. This strategy significantly enhances the electrochromic performance of the film, including rapid response and long-term cycle stability. The constructed device exhibits excellent operational stability, maintaining more than 80% of the initial optical modulation amplitude after 3000 switching cycles over 80 000 s. Achieving the multiple colors (red, green, and yellow) through voltage control holds promising potential for application in the field of multi-color electrochromic displays. The hybrid film shows superior multicolor response, ion diffusion capability, and structural stability. The film opens up promising opportunities in information encryption, and advanced optoelectronic integration.
 

Metal doped carbon dots,Prussian blue analogues,Multi-color electrochromic devices,