Synthesis Of Hole-transporting Materials Containing Triphenylamine Structure And Study On Perovskite Solar Cells

Organic inorganic halide perovskites have been widely used in solar cells and light-emitting devices due to their excellent electrical and optical properties in recent years.Perovskite solar cells(PSCs)have the advantages of simple preparation process and high photoelectric conversion efficiency(PCE)(up to 24.2%)which has become a reseach hotpot.Hole transport materials(HTM),as an important functional layer in PSCs,determine the efficiency and stability of the device while also affecting its cost.Conventional HTMs require doping additives to increase mobility,however,the commonly used additives are prone to deliquescence,which accelerate the decomposition of the perovskite material and affect the lifetime of the device.In order to solve the practicality of perovskite solar cells,improving device stability and reducing material costs have become a problem that must be solved.In this thesis,herein,two triphenylamine structural compounds 4,4’-((1E,1’E)-(3,4-dimethoxythiophene-2,5-divinyl-2,1)-bis(N,N-bis(4-methylphenyl)aniline)(DMOT-V-MeTPA,HTM1)and 4,4’-((1E,1’E)-(3,4-dimethoxythiophene)-2,5-divinyl-2,1)-bis(N,N-bis(4-methoxyphenyl)aniline)(DMOT-V-MeOTPA,HTM2)with thiophene ring as the core were designed and synthesized,as well as a triphenylamine structural compound N,N’-bis(4-benzyl)-N,N’-bis(4-(4-N,N-bis(4-benzyl)amino)phenyl)vinyl)-1,1’-biphenyl-4,4’-diamine(XY1)with TPB as the core.The structure of the intermediate and target product was identified by NMR and mass spectrometry.In order to investigate the influence of the structure of the target compound on the properties of the material,its photophysical properties,molecular energy level structure,electrochemical properties,thermal properties and film properties were investigated.The thermal decomposition temperatures of the three materials HTM1,HTM2,and XY1 were 316 ℃,362 ℃ and 399 ℃,respectively,and the glass transition temperatures were 82 ℃,99 ℃ and 101 ℃.The calculated band gaps are 2.72 eV,2.68 eV and 2.79 eV,and the LUMO levels are-5.24 eV,-5.19 eV and-5.28 eV,respectively.The HOMO levels are-2.52 eV,-2.51 eV and-2.49 eV,respectively.The root mean square surface roughness(RMS)of the spin-coated film was 1.089 nm,0.336 nm and 2.193 nm,respectively.On this basis,the three hole transport materials were applied to the perovskite solar cell,which obtained 10.58 %,12.71 % and 13.23 % of PCE,respectively.The unpackaged device was prepared by using XY1 as the HTM.When the relative humidity was 40 %,the efficiency of the device remained unchanged after 600 h aging,and the PCE of the Spiro-OMeTAD-based device decreased to 70.9 % after the same time;in the standard illumination air,the PCE of the device after 480 h aging was 69.8 %,and the PCE of the comparison device was only 24.7 %.Under the high temperature and dark condition of 85 ℃,the PCE of the device after aging for 480 h was 58.7 %,and the PCE of the comparison device was only 32.2 %.The research results show that the target compound synthesis process is simple,and the undoped device prepared as the hole transport material has better stability.