Integrated photoelectrochromic supercapacitor for applications in energy storage and smart windows

While electrochromic devices have been proposed and developed specially for multifunctional smart windows, they still need to be charged by an external power source, which increases complicated installation costs and energy consumption. In spite of efforts dedicated to develop monomer device that combines electrochromic and optoelectronic functions to address aforementioned issue, the practical application is still limited by complication in device structure, expensive cost, and unsatisfied device performance. The current work provides a facile and feasible strategy to fabricate the monomer photovoltaic electrochromic supercapacitors device by integrating dye-sensitized solar cells (DSSC) and electrochromic supercapacitors (ESC) based on the WS2-WO3 counter electrode of DSSC and WO3 electrodes of ESC. As a proof-of-concept presented here, in a typical single device, the ESC achieved an area specific capacitance of 69.9 mF cm-2 and 91.89% capacitance retention after 2000 cycles. In addition, the device exhibited a fast coloring/discoloring response in 30 s. The multifunctional smart window not only can be used as typical electrochromic window, but also can be used as energy storage device simultaneously, providing promise for a wide range of applications in buildings, airplanes, automobiles, etc.