Recent advances in flexible multifunctional electrochromic devices.

Electrochromism refers to the phenomenon in which certain materials undergo a redox reaction under an applied voltage or current, resulting in reversible changes in their optical properties and color appearance. Electrochromic devices (ECDs) show great potential in smart windows, anti-glare rear-view mirrors and displays due to the advantages of low energy consumption and simple control mechanisms. However, traditional ECDs are unfavorable for wearable and deformable optoelectronics due to the structural rigidity and limited functions. Thus, flexible ECDs integrating visual information with other advanced technologies can realize multifunctionality and further expand their application fields. This review first introduces the structure and recent development of flexible ECDs, followed by comprehensively summarizing the recent development of flexible multifunctional ECDs, including energy harvesting, energy storage, multicolor displays, and smart windows. Finally, the challenges, development trends and future prospects in flexible multifunctional ECDs are proposed and discussed. We hope that this review can guide and accelerate the development of flexible multifunctional ECDs in the new era of smart optoelectronics.