VO 2 /WO 3 -Based Hybrid Smart Windows with Thermochromic and Electrochromic Properties

The integration of electrochromic (EC) and thermochromic (TC) systems is important for realizingmultifunctional smart windows, which can adaptively control light transmittance and solar energy in response to diverse external stimuli. In this study, we developed an all-solid-state multifunctional smart window, in which tungsten oxide (WO 3 )-based EC and vanadium oxide (VO 2 )-based TC cells were integrated into a single device. In hybrid smart windows, the WO 3 -based EC layer modulates optical transmission in response to electrical voltage, while the VO 2 -based TC layer regulates solar energy transmission responding to the surrounding temperature. Therefore, such windows can control optical transmission and solar energy transmission in response to an electric stimulus and temperature change simultaneously or independently, allowing for a selective modulation of light in the visible and near-infrared regions. We demonstrated the viability of the proposed integrated smart window system by varying its optical transmission in four different optical states depending on its EC reaction and TC behavior. The concept for the integration of EC and TC cells into a single device can pave the way for next-generation multifunctional smart window systems.