Reversible Metal Electrodeposition Enabled by Composites of PEDOT:PSS/MXene for Durable Smart Windows with Broadband Electromagnetic Wave Modulation

Abstract Reversible metal electrodeposition (RME)‐based electrochromic devices (ECDs) are promising candidates for smart windows due to their simple structure and cost‐effectiveness. However, their performance is limited by unsatisfying cycling stability due to uneven metal deposition and metallic dendrite formation on the electrode. In this work, a PEDOT:PSS/MXene composite (PPM) is developed to modify ITO electrode surface. The PPM composite enhances the electrical conductivity and surface potential uniformity of ITO electrodes, guiding homogeneous Cu/Bi deposition. Moreover, the MXene component in PPM composite accelerates Cu/Bi deposition kinetics and suppresses dendrite formation. The PPM composites enable construction of large‐area smart windows with multi‐spectral electromagnetic wave modulation capabilities. The established PPM/ITO||Cu/Polyamide (PA6) exhibits stable cycling for 1,800 cycles in comparison to 970 cycles for bare ITO‐based device. Additionally, the ECD in its colored state demonstrates a superior near‐infrared blocking ability of T <10%@900–1700 nm and an X‐band electromagnetic interference shielding effectiveness of 44.5 dB@8.2–12.4 GHz. The scalability of this strategy is further demonstrated through a large‐area ECD (12 cm × 12 cm) featuring multi‐state color switching. This work offers a facile and scalable approach to enhance the cycling stability of the RME‐type ECDs and demonstrates great potential in broadband electromagnetic wave modulation toward multi‐functional smart windows.