High-performance tungsten-niobium bimetallic oxide films with designable electrochromic properties

For a better environmental sustainable development, the construction and new energy vehicle industries have paid more attention to electrochromic (EC) materials that can regulate light and heat to reduce energy use. We report a series of high-performance tungsten-niobium (W–Nb) bimetallic oxide films composed of nanowire/cluster directly grown on transparent conductive glasses by a solvothermal process. Large optical modulations in visible (Vis) (77.0%) and near-infrared (NIR) (79.7%) light regions, and high average coloration efficiency (CE‾) of 107.8 cm2·C−1 are achieved for the W–Nb bimetallic oxide films. The solvothermal preparation creates conditions for exploring the rules of the EC properties of W–Nb bimetallic oxide films with the atomic ratios of W to Nb. The EC properties of bimetallic oxides are designable by verifying their atomic ratios of W to Nb, which provides a theoretical support for searching high-performance bimetallic oxide EC films. In addition, we introduce real-time CE and CE‾ besides the traditional maximum CE to evaluate the coloration performance of the EC films. This creates a foundation for the further research on the CE of EC materials and devices in the future.