A Solar-Driven Flexible Electrochromic Supercapacitor.

Solar-driven electrochromic smart windows with energy-storage ability are promising for energy-saving buildings. In this work, a flexible photoelectrochromic device (PECD) was designed for this purpose. The PECD is composed of two flexible transparent conductive layers, a photocatalytic layer, an electrochromic material layer, and a transparent electrolyte layer. The photocatalytic layer is a dye-sensitized TiO thick film and the electrochromic layer is a WO thin film, which also possesses a supercapacitive property. Under illumination, dye-sensitized TiO thick film realizes photo-drive electrochromism that the WO changes from colorless to blue with large optical modulation. Meanwhile, the PECD has an electrochemical supercapacitance showing an energy storage property of 21 mF·cm (114.9 F·g vs the mass of WO), stable mechanical performance and long cycle performance. The PECD can effectively adjust the transmittance of visible and near-infrared light without any external power supply, realizing zero energy consumption, and can convert solar energy into electrical energy for storage.