Preparation And Performances Of Ionic Liquid Functionalized Carbon-based Hole Transport Layer-free Perovskite Solar Cells

Perovskite solar cells have become one of the most promising cells in the field of thin film cells due to their excellent photoelectric performance and relatively low manufacturing cost.In recent years,the power conversion efficiency of perovskite solar cells has jumped from 3.8%to 25.2%,showing astonishing growth rate.Considering their commercialization future,to solve the instability and to further improve the power conversion efficiency of perovskite solar cells are still enormous challenges.Till now,the quality of perovskite films and new perovskite materials are desired for improving the performances of perovskite solar cells.In this dissertation,two-dimensional/three-dimensional(2D/3D)hybrid perovskite materials were prepared by doping hydrophobic ionic liquid,and then used to construct carbon-based hole transport layer-free perovskite solar cells,achieving good stability.Furthermore,dense and uniform perovskite films were prepared by doping with hydrophobic ionic liquid,and thus to improve the power conversion efficiency and stability of perovskite solar cells.The contents of this dissertation are summarized as following:(1)Using the cation([AECPIM]⁺)of hydrophobic 1-(2-aminoethyl)-3-(4-carboxyphenyl)-3H-imidazole-1-bistrifluoromethanesulfonimidehydroiodide([AECPIM][NTF₂])ionic liquid as an organic amine cation to partly substitute methylamine cation(CH₃NH₃⁺)in CH₃NH₃Pb I₃,a novel 2D/3D hybrid perovskite structure was prepared.In addition,a variety of(AECPIM)₂(MA)_n-1Pb_nI_3n+1(n=6,8,10 and 20)2D/3D hybrid perovskite materials were designed and prepared.Then,they were used as photoactive layer for the fabrication of carbon-based hole transport layer-free perovskite solar cells.The structure of carbon-based hole transport layer-free perovskite solar cells can be denoted as FTO/c-TiO₂/m-TiO₂/(AECPIM)₂(MA)_n-1Pb_nI_3n+1/Carbon.When n=8,the power conversion efficiency of 8.91%can be obtained for the perovskite solar cell.After being exposed to the air for 42 days under unencapsulated conditions,95.16%of the initial power conversion efficiency can be reserved,meaning good stability.(2)Doping amino-functionalized hydrophobic ionic liquid 1,3-bis(2-aminoethyl)-3H-imidazole-1-bistrifluoromethanesulfonimide salt([DAEIM][NTF₂])into the perovskite precursor solution,ionic liquid-doped perovskite films have been prepared facilely.Using carbon electrode as the back electrode,carbon-based hole transport layer-free perovskite solar cells have been fabricated successfully.Through investigating the influence of the ionic liquid concentration on performances of perovskite solar cells,the optimized concentration is achieved at 0.03 mol L^-1.The maximal power conversion efficiency of the perovskite solar cell is 13.19%.Compared with the undoped perovskite solar cells,the power conversion efficiency has been enhanced 31.08%.Meanwhile,doping with[DAEIM][NTF₂]ionic liquid,the grain size of the perovskite film crystals increases and the grain boundary reduces accordingly,thus to significantly promote the transfer rate of carriers.Moreover,the hydrophobicity of the perovskite film has also been enhanced,which effectively improves the stability of the perovskite solar cells.