Scalable fabrication and reversible self-powered electrochromism remain major barriers to the practical deployment of flexible Prussian blue (PB) electrochromic devices. Here, a facile and scalable MXene-assisted in-situ fabrication strategy is developed to construct large-area PB films (40 * 60 cm²) on flexible ITO/PET substrates. Integration with a WO₃ counter electrode enables flexible electrochromic devices of the same size, demonstrating the scalability of the approach from film fabrication to device integration. Furthermore, by harnessing the intrinsic electrochemical potential gradient of the Zn-PB-MnO₂ system, a reversible self-powered electrochromic device is realized, together with smartphone-app-enabled remote control. This work establishes a simple, scalable, and cost-effective route for large-area flexible PB electrochromics while extending their functionality toward self-powered smart optical systems, offering a promising platform for flexible displays, smart windows, and energy-autonomous electrochromic technologies.

Prussian blue,large-area,self-powered