All-flexible self-cleaning hydrogel smart window with multifunctionality based on an electro-thermal manipulator

Smart windows that can repel diverse liquids are highly attractive for the development of self-cleaning building system. Despite immense achievements having been made in drophobic smart windows, unfortunately, the limitations of inferior transparency, unsatisfactory flexibility, and scarce functionality greatly hinder their practical applications. Here, a multifunctional, all-flexible and slef-cleaning electrothermal-actuated (SETA) module with superior transparency is developed by sandwiching the hydrophobic SiO₂ nanoparticles decorated silver nanowires thin-film heater and the thermo-responsive hydrogel. Through loading/discharging an electric stimulus of 5 V, the optical visibility of SETA could be in situ switched between an opaque state (T₅₅₀ = 11.0%) and a transparent state (T₅₅₀ = 84.9%) relying on the dynamically collapsed and swollen transition of hydrogel on planar and three-dimensional curved surfaces. Moreover, SETA chipset is able to repel diverse liquids, including organic and inorganic species, showcasing an excellent self-cleaning capability. Lastly, all-in-one multifunctionalities, including pixelated display, thermal regulation, defogging, and self-cleaning on a single SETA chipset, are successfully deployed. Compared to the previous windows, the current SETA chipset is more competent for optical switching in reality, owing to its portable, energy-efficient, flexible, highly-transparent, and on-demand manipulating advantages. This work provides inspirations for self-cleaning greenhouse, tunable optics, intelligent vehicles, and so on.