Integrated Electrochromic‐Electromagnetic Shielding‐Energy Storage Smart Window Based on PEDOT@Fe ₃ O ₄ Core–Shell Functional Layer

Amid intensifying energy and electromagnetic (EM)-pollution pressures, smart windows that couple light modulation with EM protection are urgently needed. Electrochromic (EC) windows offer low power and high contrast; however, multifunctional EC devices often suffer from structural complexity and unstable interfaces, impeding integration. Here, therefore a WO₃-PEDOT@Fe₃O₄ composite cathode paired with a Prussian blue (PB) anode is engineered to assemble an electromagnetic-shielding smart window (ESSW). Specifically, the ESSW delivers 53% UV-vis modulation at 611 nm, fast switching (3.1 s coloration; 4.7 s bleaching), high coloration efficiency (104.7 cm² C^-1), and durable cycling (93.4% of the initial current density after 600 cycles). Moreover, the ESSW cathode exhibits a capacitive contribution of 86.4% and an areal capacitance of 25.12 mF cm^-2 at a discharge current density of 0.2 mA cm^-2. Owing to multiple loss pathways introduced by PEDOT@Fe₃O₄, the EMI shielding effectiveness consequently rises from 15.3 dB (WO₃-ECD) to 31.8 dB (ESSW). Furthermore, a 10 cm × 10 cm spray-coated prototype demonstrates scalability and, in a sunroom scenario, reduces indoor EM-radiation intensity from 108.2 to 19.2 µW cm^-2. Such smart windows, integrating electrochromism, energy storage, and EMI shielding, show strong application potential in aerospace, energy-efficient buildings, and defense equipment.