The New Type All‐Thin‐Film Electrochromic Devices: Separated‐Function Design for High‐Performance Intelligent VIS‐IR Multi‐Band Modulation

Smart windows based on all‐thin‐film electrochromic devices (ECDs) with coordinated visible (VIS) and infrared (IR) modulation offer promising solutions for energy‐efficient buildings. However, conventional single‐layer ECDs often suffer from limited IR modulation, sluggish kinetics, poor durability, and restricted spectral control. Here, we develop a separated‐function electrochromic device (SF‐ECD) that decouples VIS and IR regulation into independent functional layers. ENZ‐ITO enables electrically driven IR modulation through carrier‐mediated localized surface plasmon resonance (LSPR), while NiO x provides VIS modulation via polaron‐based electrochromism. This architecture achieves synergistic multi‐band optical control, delivering average emissivity modulations of 0.76, 0.68, 0.75, and 0.68 across the 3–5, 8–14, 16–25, and 2.5–25 µm bands, respectively, with a maximum visible transmittance modulation of 52.1% and emissivity modulation of 0.83. The SF‐ECD exhibits rapid IR switching (<5.0 s), excellent cycling stability (>5 × 10 4 cycles), and sustained performance after 1‐year storage. Outdoor tests demonstrate a temperature reduction of 5°C–6°C under solar irradiation, highlighting its potential for advanced thermal management in intelligent buildings.