Enhanced near-infrared shielding ability of (Li,K)-codoped WO3 for smart windows: DFT prediction validated by experiment.

By means of hybrid density functional theory (DFT) computations, we found that (Li,K)-codoped WO3 shows a significantly enhanced near-infrared (NIR) absorption ability for smart windows, and investigated the influence of doping through the analysis of the electronic structures of pure and doped hexagonal WO3. Furthermore, this codoped material, with a hexagonal tungsten bronze nanostructure, was successfully prepared via a simple one-step hydrothermal reaction for the first time. Transmission electron microscopy images showed that the as-prepared products possessed a nanorod-like morphology with diameters of about 5-10 nm. It was demonstrated that (Li,K)-codoped WO3 presents a better NIR absorption ability than pure, Li-monodoped or K-monodoped WO3, which is in good agreement with our theoretical predictions. The experiment and simulation results reveal that this enhanced optical property in NIR can be explained by the existence of high free electrons existing in (Li,K)-codoped WO3.