High‐Fidelity, High‐Conductivity and Multifunctional PEDOT:PSS Hydrogel for Efficient Electromagnetic Interference Shielding and Ultrafast Response Electrochromic Applications

Abstract Poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hydrogel are promising for applications in electromagnetic interference (EMI) shielding, energy storage, and electrochromic (EC) devices. However, challenges such as low conductivity at reduced solid content, limited charge storage, poor mechanical properties, and structural distortion during solvent treatment limit their high‐performance applications. To address these issues, a high‐fidelity, high‐conductivity and multifunctional PEDOT:PSS hydrogel is developed by an ice crystal‐assisted skeleton stacking and stepwise treatment strategy, achieving ultrahigh conductivity of 87,249 S m −1 at 5.8 wt% solid content. The PEDOT:PSS hydrogel also features a charge storage capacity of 35.66 mC cm −2 and a capacitance density of 587.6 mF cm −2 . Additionally, The PEDOT:PSS hydrogel demonstrates exceptional EMI shielding effectiveness, achieving 81.2 dB, and also exhibits an ultrahigh specific surface shielding efficiency of 30,769.23 dB cm 2 g −1 . Notably, The PEDOT:PSS maintains high EMI shielding stability even after undergoing various harsh conditions. Using femtosecond laser direct writing, the highly stable all‐solid‐state EC reflective displays are developed with ultrafast response (<0.3 s) and superior durability.