Study On The Performance Of Perovskite Solar Cells Regulated By Organic Small Molecules Additives Containing C=O Groups Or F Atoms

There are various types of defects in the organic-inorganic hybrid perovskite materials prepared by the solution method,and these defects can become the center for trapping carriers and the permeation path of water molecules,which will eventually degrade the performance of the devices under the synergistic effect of external environment factors such as moisture and oxygen.Additives engineering has become an effective way to regulate the efficiency and stability of perovskite solar cells（PSCs）.In this paper,additives were introduced into PSCs by adding the organic small molecules containing C=O or F groups into the perovskite precursor solution.The devices performance can be improved by controlling the crystal growth kinetstics of perovskite films and passivating defects,and we also studied the effect of the introduction of molecules of different structures on the dynamic behavior of internal carrier in perovskite.The main research contents and results are as follows:（1）Based on the defects passivation effect of C=O group,we choosed the dipentathiophene dicarboxylic acid（TDCA）as an additive,and prepared the PSCs with different concentrations of TDCA,and explored its effect on the optoelectronic properties and stability of the device.The study shows that the introduction of TDCA can passivate the uncoordinated Pb²⁺defects in the perovskite,delay the crystallization process of the perovskite,and promote the formation of large-sized grains.Compared with the control device（PCE=19.96%）,the efficiency of PSCs was as high as 22.86%after the addition of 1.2 mg/m L TDCA.The results of long-term stability characterization at 25%relative humidity and room temperature shows that the device containing the optimal concentration of TDCA can still maintain 87%of the initial efficiency after aging for1227 h,while the reference device only maintains 70.53%.（2）On the basis of passivation defects,PSCs were prepared with tripentafluorophenylborane（TPFPB）containing hydrophobic group（-F）,the device efficiency was optimized by regulating the concentration of TFPPB,and the effect of TFPPB on the performance of PSCs was explored.The research indicates that the addition of TFPPB can effectively passivate the Pb-I antisite defect in the perovskite,improve the quality of the film,and form a hydrogen bond N-H…F between FA⁺and-F.After the introduction of 0.6 mg/m L TFPPB,devices with a PCE as high as 22.56%were prepared,while the control device was only 20.18%.Long-term stability tests at 40%～45%relative humidity and room temperature shows that the control device and the device containing the optimal concentration of TFPPB maintained 70.3%and 90.01%of their initial efficiencies after 1900 h,respectively.In conclusion,this paper can provide experimental and theoretical guidance for the selection or design of organic small molecule additives to optimize the performance of PSCs in the future.