Roadmap for electrochromic smart devices: From materials engineering and architectures design to multifunctional application

Electrochromic devices are truly promising contenders for large-scale energy-saving smart windows, low-power displays, self-dimming rear mirrors and wearable electronics because of their environmental friendliness, low power consumption, and excellent optical memory effect under open circuit conditions. Extensive research efforts have been devoted to designing and developing high-performance electrochromic devices. Nevertheless, there are still challenges to realizing their full potential and meeting the performance requirements of commercial applications. This review comprehensively covers and evaluates the recent advances and current limitations along with possible solutions in the pursuit of high-performance electrochromic devices. To guide the future fabrication of high-performance electrochromic devices, considerable emphasis is paid to the design of high-quality electrochromic materials, ion storage materials, electrolytes satisfying wide voltage windows, high ionic conductivity, and high transparency. The solution-processed film-coating methods and the selection strategies of transparent conducting electrodes are also discussed, considering sealing methods and bus-bars formation. Moreover, recent advances in multifunctional electrochromic devices were elaborately reviewed. Ultimately, the future challenges and perspectives of electrochromic devices are outlined. We believe that these analyses and summaries are valuable for a systematic understanding of the structure–activity relationship in electrochromic materials and serve as roadmap for rationally constructing material and surface/interface structures in electrochromic devices.