Bridging to Commercialization: Record‐Breaking of Ultra‐Large and Superior Cyclic Stability Tungsten Oxide Electrochromic Smart Window

Electrochromic smart windows (ESWs) can significantly reduce energy consumption in buildings, but their cost-effective, large-scale production remains a challenge. In this study, the instability of black phosphorus is leveraged to induce the growth of the tungsten oxide film through its decomposition process, inspired by the 2D material-assisted in situ growth (TAIG) method. This approach results in the preparation of large-scale, high-performance WO_3-x·nH₂O (n < 2) films. Characterization techniques and DFT calculations confirm efficient regulation of structural water and oxygen vacancies during TAIG preparation. The WO_3-x·nH₂O films exhibit excellent electrochromic (EC) properties, including high transmittance modulation (74.2%@1100 nm), fast switching time (t_c= 5.5 s, t_b= 3.8 s), high coloration efficiency (124.7 cm² C^-1), and superior cyclic stability (transmittance modulation retained 94.7% after 20 000 cycles). Ultra-large WO_3-x·nH₂O film are prepared via a simple immersion process, and fabricated into a large-area ESW under facile laboratory conditions, demonstrating the economic and practical feasibility of this approach in industrial-scale production. Operated by the intelligent control circuit, the ESW exhibits remarkable EC properties and cyclic stability This research represents a milestone in improving the performance and industrial-scale production of ESWs, bridging the gap to the commercialization of EC technology.