Nano Aerogel-Based VIS-NIR Switchable Electrochromic Supercapacitor: Energy Storage and Heat-Shielding Device.

Power-efficient electrochromic devices that can exhibit multifunctional applications, especially in the areas of energy storage and savings, are increasingly in demand. Here, an inorganic-organic electrochromic smart window has been designed in which a self-supporting aerogel-type network of tin-doped indium oxide (a-ITO) nanoparticles was doped to enable applications in supercapacitive energy storage. The devices based on poly(3-hexylthiophene-2,5-diyl) (doped with incorporated a-ITO) and viologen exhibit bias-induced color modulation in the visible and infrared range. This function can be employed to prevent the transmission of latter radiation to maintain a temperature difference on the two sides of the device when it is turned ON with a bias voltage of 1.6 V. The device exhibits an electrochromic supercapacitor property with a maximum coloration efficiency of 966 cm/C with a switching time of only 0.5 s, color contrast of 61%, and high specific capacitance of 17 F/g. Potential applications of the device in temperature shielding are discussed, and a maximum cooling efficiency of 32% is demonstrated. Overall, a recipe is developed to design energy-storing and energy-saving multicolor-switchable smart windows for application in designing energy-efficient smart windows/buildings.