Flexible Normally Transparent Smart Window Modulating Near‐Infrared Penetration under Ambient Conditions

Smart windows that both reversibly occlude visible light and modulate the penetration of near-infrared (NIR) light save a great deal of energy. Here, a simple, super-fast, electrically switchable smart window that initially reflects NIR light and then scatters it in response to thermal stimuli is designed and fabricated. Transparent polymer-stabilized cholesteric liquid crystals (PSCLCs) are prepared by photo-polymerizing RM 257 monomers in which the planar CLCs fully reflected NIR light (1050–1550 nm). Next, an ultra-thin, thermotropic, W0.003V0.997O2-doped polyvinylpyrrolidone hybrid thin layer that modulates NIR light penetration over a very broad temperature range is overlaid on the PSCLCs, and the final WVO-PSCLCs smart window features four NIR modulation modes. Specifically, when a model wood house with three 1.5- × 2-cm WVO-PSCLCs smart windows is thermally irradiated by a 250-W infrared light for 10 min, the internal temperature is 4.8 °C less than that of a house lacking smart windows. Flexible smart windows fabricated from polyethylene terephthalate (PET) could be bent through a radius of 15 mm without any noticeable damage, and are very resistant to external vertical pressure. The flexible WVO-PSCLCs smart windows are versatile, and afford outstanding transparency management and modulation of NIR light penetration.