Flexible core-shell Cs x WO 3 -based films with high UV/NIR filtration efficiency and stability.

Cesium-doped tungsten bronze Cs x WO 3 (CWO) is an ideal near infrared (NIR) shielding material for solar filters. However, the NIR shielding ability of CWO-dispersed films easily deteriorates in hot humid environments, which severely hinders the commercial application of CWO. In this paper, UV/NIR shielding nanocomposite films were prepared by dispersing core-shell structured CWO@polydopamine (CWO@PDA) in a poly(vinyl alcohol) matrix. Because of the strong ultraviolet light absorption ability of PDA, it can shield ultraviolet light, which is generally detrimental to our health. The prepared nanocomposite films can efficiently shield 88.3% UV and 85.5% NIR radiation even though they show relatively high transparency in the visible range. Importantly, the good protection of the continuous PDA shells played an important role in enhancing the stability of CWO nanoparticles. The nanocomposite films also exhibit excellent stability in hot humid environments. Therefore, core-shell structured CWO@PDA nanoparticles have great potential as a novel UV/NIR shielding material for the development of efficient energy-saving windows.