Flexible thermochromic window based on hybridized VO₂/graphene

Large-scale integration of vanadium dioxide (VO₂) on mechanically flexible substrates is critical to the realization of flexible smart window films that can respond to environmental temperatures to modulate light transmittance. Until now, the formation of highly crystalline and stoichiometric VO₂ on flexible substrate has not been demonstrated due to the high-temperature condition for VO₂ growth. Here, we demonstrate a VO₂-based thermochromic film with unprecedented mechanical flexibility by employing graphene as a versatile platform for VO ₂. The graphene effectively functions as an atomically thin, flexible, yet robust support which enables the formation of stoichiometric VO₂ crystals with temperature-driven phase transition characteristics. The graphene-supported VO₂ was capable of being transferred to a plastic substrate, forming a new type of flexible thermochromic film. The flexible VO₂ films were then integrated into the mock-up house, exhibiting its efficient operation to reduce the in-house temperature under infrared irradiation. These results provide important progress for the fabrication of flexible thermochromic films for energy-saving windows.