Tungsten bronze CsxWO3 nanopowders doped by Ti to enhance transparent thermal insulation ability for energy saving

Cesium tungsten bronze (CsxWO3), a unique energy-saving material, has attracted great interest because of its excellent visible transmittance and near-infrared absorption. In order to improve its optical properties, the Ti doping modification was carried out in this work, and a series of Ti-doped CsXWO3 (Ti-CsxWO3) nanopowders were synthesized by a solvothermal reaction and post-annealing. The 1.71 at. % of Ti dopants achieved remarkable enhancement of both integral visible transmittance (Tlum, 380–780 nm) and near-infrared shielding efficiency (ΨNIR, 780–2500 nm) of CsxWO3. The Tlum and ΨNIR of the 1.71 at. % Ti-CsxWO3 polymer film reaches 63.87 % and 76.90 %, respectively, higher by 51.88 % and 65.00 % than those of the CsxWO3 film. The improvement of Tlum is attributed to the broadening of band gap and smaller size of the nanoparticles induced by Ti doping, and the enhanced ΨNIR would result from the increased free electron concentration and energy levels of impurities. The incorporation of Ti elements renders CsxWO3 a promising application in the field of energy saving.