High-Performance Thermochromic VO₂-Based Coatings Deposited by Roll-to-Roll High-Power Impulse Magnetron Sputtering

Thermochromic vanadium dioxide (VO2) undergoes a reversible semiconductor-to-metal transition, a property that can be exploited for reduction of the energy consumption in buildings using smart windows. Herein, high-performance thermochromic three-layer ZrO2/V0.98W0.02O2/ZrO2 coatings prepared on ultrathin flexible glass (0.1 mm) without any post annealing in a pilot-scale roll-to-roll deposition device are presented. The V0.98W0.02O2 layers are deposited using a reactive high-power impulse magnetron sputtering with an oxygen flow control at a substrate temperature of approximately 350 degree celsius. The optimized coatings (width of 0.3 m and length over 2.6 m) exhibit a transition temperature of 28 degree celsius, an integral luminous transmittance over 50%, and a modulation of the solar energy transmittance of about 10%. The deposition process is optimized, and the elemental composition (Rutherford backscattering spectrometry), design (field-emission scanning electron microscopy), phase composition (X-ray diffraction), and thermochromic properties (spectrophotometry) of these high-performance VO2-based coatings in the context of potential for commercial applications are characterized.