Thermochromic performances of tungsten-doping porous VO 2 thin films

Using the vanadium oxyacetylacetone (VO(AcAc) 2 ) as the precursor and white powdery tungstic acid as the doping W source, we fabricated the W-doped porous VO 2 films by spin-coating method followed by annealing under the N 2 atmosphere at 550 °C for half an hour. Compared to the pure VO 2 film, the 5 at.% W-doped film exhibits a simultaneous enhancement of the near-IR switching efficiency at 2000 nm from 47.5 to 55.0 % and the maximum value of visible transmittance at 30 °C from 39.5 to 46.7 % as well as the one at 90 °C from 44.7 to 58.1 %, which further confirmed the practicability of introducing pores into the VO 2 film as a strategy to enhance the thermochromic properties. In addition, a possible connection is presented about the relationship of metal–insulator transition process and the evolution of the phase compositions and morphology. Graphical Abstract A possible connection between the morphology and the thermochromic performance for the W-doped VO 2 films was presented.