Flexible Thermochromic Window Based on Hybridized VO₂/Graphene

Abstract

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 VO2. 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.

Hydrothermal Synthesis of VO2 Polymorphs: Advantages, Challenges and Prospects for the Application of Energy Efficient Smart Windows

“…Various TCE materials, such as Ag nanowires, carbon nanotube, Al‐doped ZnO, ITO/FTO and graphene are incorporated with VO 2 to activate its thermochromic performance. Specially, as shown in Figure a–d, the electrothermochromic device combining VO 2 nanoparticles with ultra‐long Ag nanowires can regulate the infrared transmittance dynamically as the input voltage and action time change.…”

Properties and Applications of Thermochromic Vanadium Dioxide Smart Coatings

“…In addition, it is clear that progress towards commercial "smart windows" continues to be made in leaps and bounds with the improvement of their transmittance in the visible portion of the spectrum and in solar modulation efficiency 132,137,138 Finally, we can all look forward to the use of VO 2 in combination with noble metals in the fabrication of plasmonic-and metamaterial-based devices that can be used in a wide variety of applications including (but not limited to) optical modulators, 139 negative capacitors, 140 field effect transistors, 141 active shutters, 142 optical limiting devices, 143 sunshields for spacecraft, 144 and photonic resonators. In addition, it is clear that progress towards commercial "smart windows" continues to be made in leaps and bounds with the improvement of their transmittance in the visible portion of the spectrum and in solar modulation efficiency 132,137,138 Finally, we can all look forward to the use of VO 2 in combination with noble metals in the fabrication of plasmonic-and metamaterial-based devices that can be used in a wide variety of applications including (but not limited to) optical modulators, 139 negative capacitors, 140 field effect transistors, 141 active shutters, 142 optical limiting devices, 143 sunshields for spacecraft, 144 and photonic resonators.…”

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

“…Kim et al have introduced the use of VO 2 –graphene hybrid materials for the fabrication of thermochromic films for energy saving windows. VO 2 crystals have been prepared on graphene and the graphene-supported VO 2 is easily transferred to a plastic substrate which enables formation of a new type of flexible thermochromic film [117]. This hybrid film exhibits efficient operation to reduce the in-house temperature under infrared irradiation.…”