Highly Transparent Photochromic Coating with Excellent Dimming Capability Based on B─O─W Coordination Bonding Strategy

Abstract Photochromic smart windows with efficient solar heat and sunlight modulation are highly sought after for energy efficiency in buildings. However, the preparation of organic‐inorganic hybrid photochromic coating with high transparency and excellent dimming ability remains a challenge. Here, we achieve a high dispersion of inorganic nanoparticles in the polymer network based on the B─O─W coordination bond locking strategy, and effectively reduce the energy band gap of Phosphotungstic acid (PTA) by adjusting the local coordination and electronic environment of the metal centre (W) to design a novel conjugated organic‐inorganic hybrid photochromic material with high transparency (96.4%), rapid photoresponse (colouring in10 s), and excellent dimming ability (reaching saturation state in 20 min, Visible light modulation range △ T 550 nm = 87.1%, △ T 749 nm = 94.0%). Selective heating and cooling of interiors in winter and summer shows excellent potential for improving indoor sunlight comfort and increasing energy efficiency in buildings.