VO2/AZO double-layer films with thermochromism and low-emissivity for smart window applications

Utilizing magnetron sputtering technology, VO2/AZO double-layer films were successfully prepared on glass and characterized by temperature-dependent transmitting spectra, reflective spectra, X-ray diffraction (XRD) and scanning electron microscopy (SEM). With good transmittance (48% at 80 °C and 43% at 20 °C) in visible region, the fabricated VO2/AZO double-layer films have a thermochromic property of 27% transmitting variance in near-infrared region and a low-emissivity of 0.66 (compared to 0.9 of single VO2 film). As for thermal hysteresis loop, compared with single VO2 film owning a transmitting variance of 25% and a temperature width of 27 °C, the VO2/AZO double-layer films have a similar transmitting variance of 27% but a narrower temperature width of 17 °C. SEM micrographs show that AZO substrate can promote the oriented growth of VO2 films. The present work provides a proof about the feasibility to fabricate the multi-functional films with thermochromism and low-emissivity.