| In order to alleviate problems such as the energy crisis and environmental pollution,it is urgent to develop clean and renewable energy sources such as solar energy,wind energy,geothermal energy,tidal energy,and water energy.Solar energy has attracted special attention due to its characteristics of being cheap,readily available,inexhaustible,and environmentally friendly.Quantum dot sensitized solar cells are developed from the concept of dye-sensitized solar cells.They directly convert solar energy into electricity.They have the characteristics of simple preparation process,easy acquisition of raw materials,and low cost.However,the conversion efficiency of quantum dot-sensitized solar cells is still far below the shockley-Queisser energy conversion limit.At present,the conversion efficiency is mainly improved from the aspects of photoanode,quantum dots,electrolyte,and counter electrode.In this paper,the photoelectric conversion efficiency of quantum dot-sensitized solar cells is improved by optimizing the preparation process of solar cells,accelerating the rapid deposition of quantum dots,improving the counter electrode,and increasing the catalytic ability of the counter electrode.(1)In the rapid deposition method,the oil phase ZnCuInSe quantum dots were prepared.In the dichloromethane solution of the quantum dots,acetone,ethanol,methyl acetate and other reagents were added by chemical titration,and the polarity of the solvent was changed until the metastable state of the quantum dots just occurred.By heating and evaporating the solvent,the quantum dots can be deposited rapidly.Save the deposition time of quantum dots,simplify the process conditions of quantum dots sensitized solar cells,improve the loading capacity of quantum dots,improve the absorption coefficient of photoanode,and improve the photoelectric conversion efficiency of solar cells.The short-circuit current of the solar cell with dichloromethane and methyl acetate as solvent can reach 21.02 mA/cm2,the filling factor can reach 49.2%,the photoelectric conversion efficiency can reach 5.31%,and the short-circuit current of the quantum dots with ligand exchange deposition can reach 22.84 mA/cm2,filling factor 45.5%,photoelectric conversion efficiency 5.45%.Compared with the ligand guided self-assembly method,the time of vapor dry deposition can be reduced from three hours to ten minutes.(2)The ZIF-8 carbonized electrode was prepared by preparing ZIF-8 and carbon material obtained by high-temperature carbonization,and the three-dimensional graphene electrode was prepared using commercial magnesium oxide nanoparticles as a template and the carbon material obtained by CVD method.The short-circuit current of ZIF-8 carbonized electrode can reach 22.36 mA/cm2,the fill factor can reach 47.1%,the conversion efficiency can reach 5.58%,the short-circuit current of the three-dimensional graphene electrode can reach 22.52 mA/cm2,the fill factor can reach 48.4%,the conversion efficiency up to 5.67%.In order to further improve the catalytic performance of the counter electrode,Cu2S nanoparticles were combined with different carbon materials to obtain a new slurry to prepare the counter electrode,which improved the photoelectric conversion efficiency of quantum dot sensitized solar cells.By optimizing the mixing ratio of Cu2S nanoparticles and carbon materials,the short-circuit current of the counter electrode prepared by the mixed slurry of ZIF-8 carbonized material and Cu2S can reach 22.82 mA/cm2,the fill factor can reach 52.6%,the conversion efficiency can reach 6.36%.Compared with the ZIF-8 carbonized electrode,the photoelectric conversion efficiency is increased by 14%.The short-circuit current of the counter electrode prepared by the mixed slurry of 3D graphene and Cu2S can reach 23.07 mA/cm2,the fill factor can reach 55.6%,and the conversion efficiency can reach 6.67%.Compared with the 3D graphene electrode,the photoelectric conversion efficiency is increased by 17%. |
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