A Solar-Driven Flexible Electrochromic Supercapacitor

Abstract

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 TiO2 thick film and the electrochromic layer is a WO3 thin film, which also possesses a supercapacitive property. Under illumination, dye-sensitized TiO2 thick film realizes photo-drive electrochromism that the WO3 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−2 (114.9 F·g−1 vs the mass of WO3), 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.

Advances in Electrochemical Energy Devices Constructed with Tungsten Oxide-Based Nanomaterials

“…This idea is backed by the following reasons. Firstly, the open circuit voltage of the solar cells matches the relevantly low driving voltage of the tungsten oxide-based bifunctional device well [ 30 , 140 ]. Secondly, their positions in a building are not exclusive so that they can operate free of the influence of each other, thus achieving highly efficient energy use [ 185 ].…”

“…The EC part and PV part share the same electrolyte and typically, this kind of integrated method has to sacrifice a certain area of the window. For example, Zhang et al [ 30 ] designed a trifunctional device, photoelectrochromic device (PECD), in which WO 3 and TiO 2 were both used as the anode and Pt was used as the counter electrode ( Figure 18 a,b). When the device is open circuit and exposed to sunlight, dye molecules in the electrolyte are excited and electron-hole pairs are generated.…”

“…We can get direct information about their working condition from color signals, bringing us great convenience and safety, or we can see it as a transparent battery and make good use of the energy stored in it, reducing electricity consumption. Moreover, these bifunctional devices can have more possibilities by integrating other parts, such as solar cells, so that self-powered systems are achieved [ 30 , 31 ]. Further, it can output power generated by the solar cells to effectively use the energy.…”

Photosupercapacitors: A perspective of planar and flexible dual functioning devices

“…Whereas, storage device using NCS electrode shows retention of 90% of their initial capacitance (specific capacitance of 224.6 F/g). Recently, apart from SC, flexible DSSC was integrated with electrochromic devices (ECDs) with energy‐storage ability and the electrolyte is shared by two devices to achieve solar‐driven electrochromism phenomena for smart windows and other applications (Xu et al, 2019; Zhang et al, 2020). Although the research on developing such fiber‐based DSSC and SCs devices started a decade ago, this area is growing remarkably, and further improvement is envisaged in energy conversion and storage performance of the integrated device.…”

A light-fostered supercapacitor performance of multi-layered ReS2 grown on conducting substrates

“…Smart supercapacitors with ability to charge when exposed to light is an attractive research area for developing next generation energy storage devices [1][2][3][4][5][6][7][8][9][10][11][12] . Light sensitive direct band gap semiconductor materials with energy storage capacity are of great importance for such light tunable supercapacitor performances.…”