Reducing transition temperature and diluting brown-yellow color of VO2 films via embedding Ag particles periodic arrays

In most previous investigations on VO2 smart windows, a low transition temperature (Tc) and desirable color have not been taken simultaneously, considering that they have not received enough study as yet. Here Ag particles periodic arrays (PPAs) were successfully embedded into monoclinic VO2(M) via self-assembly hexagonal-close-packed polystyrene templates. With the increase of Ag PPAs specific area, the Tc was reduced from 68 to 57.5 °C and the carrier density was increased. The mechanism of Tc reduction of Ag PPAs/VO2 composite films was clearly explained: more free electrons injected into VO2(M) films induces the larger absorbing energy at the nanometal-semiconductor junction. By changing the Ag PPAs specific area, the strong absorption of light in the ~630–730 nm (brown-yellow) band was achieved, thereby diluting the influence of the inherent brown-yellow color of the VO2(M) film. A low Tc and diluted color of the VO2(M) were simultaneously achieved by tuning Ag PPAs specific area, benefiting for the smart window application.