Quasi-Solid-State Composite Electrolytes Of Dye Sensitized Solar Cells Based On Electrospun PVDF Nanofibre Membranes

Dye-sensitized solar cells?DSSCs?are one of the new types of solar cell developed in recent years,it is called the third-generation solar cell.The research progress of DSSCs in recent years has been how to improve the photoelectric conversion efficiency of cells from the perspective of material selection and design;and how to focus on the assembly characteristics of devices.In the development of DSSCs key materials,it is mainly to find a more suitable electrolyte material,optical electrode material,to improve the photoelectric conversion efficiency and the stability of the DSSCs,and other key parameters.Currently,the electrolytes used as DSSCs is mainly liquid electrolytes,which can make the cells have higher photoelectric conversion efficiency,however,there are obvious disadvantages when it is used,such as the problem of volatile leakage of organic solvents,which seriously slows down the process of large-scale commercialization of DSSCs.Based on these reasons,from the perspective of material selection and design,we intend to research and develop a new type of quasi-solid electrolyte material that can simultaneously make DSSCs with high photoelectric conversion efficiency and stability.The specific research content is as follows:1.Polyvinylidene fluoride?PVDF?membranes were prepared by electrospinning technique.Electrospun PVDF films were immersed in commercial ionic liquid electrolyte to prepare quasi-solid-state composite electrolyte.And then these quasi-solid-state composite electrolytes were used to fabricate DSSCs by the way of heat-press?110??.The results indicated that electrospun PVDF membrane has a three-dimensional network structure with extremely high porosity.The membrane can withstand the conditions of hot-press,showed excellent absorption property for ionic liquid electrolyte,good thermal stability and mechanical strength.The results show that compared to liquid electrolyte,the design of the quasi-solid composite electrolyte,not only keeps the high conversion efficiency of DSSCs,but also enhances the stability.2.In this study,a polydopamine?PDA?coating polyvinylidene fluoride?PVDF?composite membrane?PDA@PVDF?was prepared by using a simple dip coating method to grow a thin layer?PDA?on the surface of electrospun PVDF nanofiber membrane.The PDA@PVDF composite membrane was immersed in commercial ionic liquid electrolyte to prepare quasi-solid-state composite electrolyte,and the quasi-solid-state electrolyte was used to fabricate dye sensitized solar cells?DSSCs?.The results show that the PDA coating does not harm the three-dimensional network structure of PVDF nanofiber membrane.Compared with pure PVDF nanofiber membrane,the PDA@PVDF composite membrane exhibits better hydrophilicity,much higher thermal stability and better mechanical propertie.DSSCs assembled with quasi-solid-state composite electrolyte composed of PDA@PVDF composite membrane have better stability than DSSCs assembled with ionic liquid electrolyte and quasi-solid-state composite electrolyte composed of pure electrospun PVDF nanofiber membrane.3.Si O₂modifying polyvinylidene fluoride membrane?Si O₂@PVDF?was prepared by using the principle of in-situ sol-gel method to coat Si O₂nanoparticles on the surface of PDA@PVDF fiber membrane.The Si O₂@PVDF composite membrane was immersed in ionic liquid electrolyte to prepare quasi-solid-state composite electrolyte.And then the quasi-solid-state composite electrolyte was used to fabricate DSSCs by the way of hot-press?110??.The results show that Si O₂can be evenly coated on the fiber surface of the fiber membrane,and the Si O₂@PVDF composite film has higher thermal stability and mechanical properties than the pure membrane.In addition,the DSSCs assembled by the quasi-solid-state composite electrolyte composed of the composite membrane of Si O₂@PVDF ensures higher photoelectric conversion efficiency and stability.4.Ti O₂modifying PVDF membrane?Ti O₂@PVDF?was prepared by using the principle of in-situ sol-gel method to coat Ti O₂nanoparticles on the surface of PDA@PVDF composite membrane.The Ti O₂@PVDF composite membrane was immersed in ionic liquid electrolyte to prepare quasi-solid-state composite electrolyte.And then the quasi-solid-state composite electrolytes were used to fabricate DSSCs by the way of hot-pressing?110??.The results show that the Ti O₂@PVDF composite film has better strength and toughness than pure PVDF nanofiber membrane.Through the stability test,it is found that the DSSCs using quasi-solid-state composite electrolytes show superior stability than the ionic liquid electrolyte battery.