Design Of Photolelectrochromic Energy-storage Devices And Their Performance

Photoelectrochromic device is one kind of devices combining photovoltaic device and electrochromic device,which can use solar energy to adjust its own optical transmittance and realize self-powered.It has a broad application prospect in the field of building energy saving.At present,the existing photoelectrochromic devices have complex structure,poor electrochemical performance,single working mode,and no energy storage function,which is difficult to meet the practical application requirements.In this paper,several kinds of photoelectrochromic devices are designed.The tungsten oxide film is used as electrochromic and energy storage layer.The influence of its morphology on the photoelectrochromic performance is studied,and the application of photoelectrochromic devices in energy storage is explored.The Prussian blue film is used as a pair of complementary matching electrodes with the tungsten oxide film,which realizes the multi working mode and the function of energy storage.A semi solid photoelectrochromic device was designed,and the effects of gel electrolyte layer and hole transport layer on the performance of it are investigated.The main research contents of this paper are as follows:1.Dense tungsten oxide films were prepared by magnetron sputtering,mesoporous tungsten oxide films were prepared by polymer-assisted sol-gel method.The two kinds of tungsten oxide films with different morphologies were assembled into photoelectrochromic devices and the optical and electrochemical properties of the two devices were compared.The assembled device can convert solar energy into electricity and store it,as well as regulate transmittance of visible light and near-infrared light.Compared with the photoelectrochromic device assembled by the dense tungsten oxide film,the photoelectrochromic device assembled by the mesoporous tungsten oxide film have a higher optical modulation.Meanwhile,the device assembled by the mesoporous tungsten oxide film exhibited a specific capacitance of 147.75 F/g after photo-charging,which is higher than the the device assembled by the dense tungsten oxide film.In addition,the device assembled by mesoporous tungsten oxide film exhibited more stable cyclic properties than the device assembled by dense tungsten oxide film.2.Prussian blue films were prepared by electrodeposition method and used as the complementary electrochromic counter electrode of tungsten oxide to assemble a multimode photoelectrochromic device.The photoelectrochromic device has four working modes:warm,cool,bright and dark,which can meet different requirements of users,especially can block near-infrared light in dark mode.The photoelectrochromic device also has the function of adjusting brightness,temperature and energy storage,and it can be charged with light or electricity when used as a supercapacitor,showing a specific capacitance of 11.49 m F/cm² during electrical charging and 8.59 m F/cm²during photo-charging.In addition,the photoelectrochromic device also shows good cyclic performance,and its optical transmittance at 510 nm can maintain 88.5%after2000 cycles.3.The Prussian white film was used as the counter electrode of tungsten oxide film and the gel electrolyte is prepared by PEO to fabricate a semi-solid photoelectrochromic device with complementary structure,the effect of the electrolyte thickness on the performance of itwas also studied.The PW film and WO₃ film of the device with 2 mm thickness electrolyte can not achieve coloring and bleaching at the same time,and the device's optical modulation range is narrow but it has the property of energy storage.The device with electrolyte thickness of 15?m adds a hole transport layer on the surface of Ti O₂/WO₃/FTO electrode,and the PW film and WO₃ film can color at the same time under light,and realize bleaching at the same time by short circuit in the dark.It has53%optical modulation range at 496 nm,but it has no energy storage property.