Scalable and High-Performance Infrared Electrochromic Devices Enabled by Solvent-Engineered PEDOT/PSS Films

Poly(3,4-ethylenedioxythiophene) (PEDOT) based infrared electrochromic devices (IR-ECDs) show great potential for dynamic thermal management applications. However, their practical deployment is limited by a slow response, poor cycling stability, and scalable fabrication challenges. In this study, we report a scalable, solution-processed strategy for fabricating large-area, flexible PEDOT/PSS IR-ECDs using a one-step solvent post-treatment to selectively remove insulating PSS. This treatment markedly enhances film conductivity, which, in turn, accelerates charge transport and facilitates robust electrochromic switching. The resulting devices demonstrate rapid switching behavior, excellent cycling stability, and a notable mid-infrared emissivity modulation (Δϵ_{8-14 μm}) of 0.23. Theoretical and experimental results reveal that IR modulation of PEDOT/PSS arises primarily from conductivity changes driven by reversible ion doping/dedoping. When the conductivity exceeds ∼500 S/cm, its long-wave IR reflectance closely follows predictions from Drude theory. This study not only offers new insights into the IR electrochromic mechanism of PEDOT/PSS but also opens up opportunities for scalable, cost-effective, and high-performance thermal modulation technologies with potential applications in adaptive concealment, information display, and intelligent thermal regulation.