First principles investigation on Li or Sn codoped hexagonal tungsten bronzes as the near-infrared shielding material

The 52% energy of the solar radiation is contributed by near-infrared radiation (NIR, 780–2500 nm). Therefore, the material design for the energy-saving smart window, which can effectively shield NIR and has acceptable visible transmittance, is vital to save the energy consumed on the temperature control system. It is important to find a non-toxic stable material with excellent NIR-shielding ability and acceptable visible transmittance. The systematic first-principles study on Li x Sn y WO 3 ( x = 0, 0.33, 0.66, and y = 0, 0.33) exhibits that the chemical stability is a positive correlation with the doping concentration. After doping, the Fermi-energy upshifts into the conduction band, and the material shows metal-like characteristics. Therefore, these structures Li x Sn y WO 3 (except the structure with x = 0.33 and y = 0) show pronounced improvement of NIR shielding ability. Our results indicate that when x = 0 and y = 0.33, the material exhibits the strongest NIR-shielding ability, satisfying chemical stability, wide NIR-shielding range (780–2500 nm), and acceptable visible transmittance. This work provides a good choice for experimental study on NIR shielding material for the energy-saving window.