Sputtering Flexible VO₂ Films for Effective Thermal Modulation

Abstract

Flexible vanadium dioxide (VO₂) thermochromic films show great potential for large-scale fabrication and possess broader applications compared with VO₂ coatings on rigid substrates. However, the fabrication of flexible VO₂ films remains a challenge so far, leading to the scarcity of research on flexible VO₂ films for smart windows. With the aim to obtain a flexible VO₂-based films with excellent optical properties and a long service life, we designed and successfully fabricated a flexible ITO/VO₂/ITO (IVI) film on the colorless transparent polyimide substrate, which could be directly attached to glasses for indoor temperature modulation. This flexible IVI film effectively enhances the luminous transmittance (<i>T</i>_lum) and solar modulation ability (Δ<i>T</i>_sol) (15 and 68% increase relative to a VO₂ single layer), reduces the thermal emissivity (ε_T) (50.7% decrease relative to a VO₂ single layer), and exhibits better durability than previously reported structures. Such excellent comprehensive performance offers it great potential in practical applications on smart windows. This work is supposed to provide a new strategy for facile direct fabrication of flexible VO₂ films and broaden the applications of flexible VO₂ in more coatings and devices.