Modified color for VO₂/Au/VO₂ sandwich structure-based smart windows

In this study, the VO₂/Au/VO₂ sandwiched structure was fabricated by rapid thermal annealing of sputtered V/Au/V sandwiched structure to modify the intrinsic unpleasant brown–yellow color of VO₂ films based on the localized surface plasmon resonance (LSPR) for smart windows. The morphology, crystalline structures, and optical transmittance spectra of the sandwich structure were characterized by scanning electron microscopy, X-ray diffraction and UV-VIS-NIR spectrophotometry, respectively. The obtained results indicate that the VO₂/Au/VO₂ sandwich structure with different Au nanoparticles sizes shows different color from brown–yellow to blue–green due to the appearance and redshift of LSPR peak. Moreover, the phase-transition temperature for the optimized VO₂/Au/VO₂ sandwich structure was only 42.5 °C, far below 68 °C for bulky VO₂. The optimized VO₂/Au/VO₂ thin films could simultaneously meet the requirements of comfortable color and a reduced phase-transition temperature, and these excellent features would benefit the practical application of VO₂ thin film-based smart windows.