Study On The Influence Of Morphology Control And Interface Modify On The Performance Of Perovskite Solar Cells

Organic-inorganic halide perovskite solar cells have received extensive attention in the photovoltaic field due to their excellent photoelectric properties,and their photoelectric conversion efficiency has exceeded 25%.Although great research progress has been made in the working mechanism and preparation process,perovskite solar cells are still facing some problems in the process of moving from the laboratory to marketization,such as how to further improve the stability of perovskite solar cells to reach the level of commercial application;how to further broaden the light absorption range of the perovskite cell to improve its photoelectric conversion efficiency.The perovskite layer,as the core part of the perovskite solar cell,its composition,crystallinity,morphology,and light absorption properties play a vital role in improving the performance of the device.At present,the main methods to improve the performance of perovskite cells include additive engineering,component engineering and interface engineering.Based on this,the thesis focuses on the nucleation and growth of perovskite film crystals,the quality control of perovskite film,the factors affecting stability,and the light absorption spectrum.The main research contents of the thesis are as follows:1.Rigid organic polycarboxylic acid is introduced in the preparation process to improve the quality of perovskite films.(1)Trimellitic acid(TMA)is introduced to the lead iodide precursor solution to intervene the crystallization process of the MAPb I₃ perovskite film and regulate the formation of crystal nuclei during the film formation process.The-COOH of TMA chelates with Pb²⁺in the perovskite to form an intermediate phase,which prolongs the crystallization time and causes uniform coverage of the perovskite film on the substrate,thereby forming a high-quality perovskite film.Finally,the photoelectric conversion efficiency(PCE)of the perovskite solar cell with TMA increase from14.68%to 17.21%,and has good stability.(2)In order to passivate the defects of the perovskite film when regulating the crystallization process,3,3',5,5'-azobenzene-tetracarboxylic acid(H₄abtc)is introduced into the preparation process of the MAPb I₃ perovskite solar cell.The multifunctional H₄abtc not only significantly improve the stability of the device due to its own structural characteristics,but also adjust the nucleation and crystallization process of the perovskite film.In addition,the Lewis acid base adduct formed by adding H₄abtc can passivate the defects of the perovskite film,thereby inhibiting the non-radiative recombination of charges,finally improving the photoelectric performance of the device.After fabricating the perovskite film with the H₄abtc,a PCE of 17.67%is obtained,which is significantly higher than the efficiency of the perovskite solar cell(14.25%)without the H₄abtc.2.Device aging under oxygen atmosphere has a significant impact on the performance of perovskite photovoltaic cells.The perovskite(MAPb X₃(X=I,Br))cell is placed in an oxygen atmosphere dark condition with a humidity of<10%for different times to explore the influence of O₂ on the passivation of perovskite film defects,and the transient photovoltage(TPV)technology is used to analyze the ion migration of the device before and after aging under different illumination times.The results show that after aging treatment,devices with different halogens show different effects.The performance of devices based on MAPb Br₃ has been significantly improved,and the photoelectric conversion efficiency increases from 3.48%to 6.05%;while the relative performance of devices based on MAPb I₃ reduce,and the photoelectric conversion efficiency decreases from 16.3%to 15.0%.The reason may be because O₂ has the effect of passivating the defects of the perovskite film,but in dark conditions,the degree of oxygen or air diffusion depends on the composition of the perovskite materials,resulting in significant differences in the performance of MAPb I₃ and MAPb Br₃ solar cells.3.To increase the light absorption spectrum of the perovskite solar cell,a narrow band gap organic heterojunction PM6:Y6 is directly deposited on the perovskite layer to construct a perovskite/organic integrated photovoltaic cell(MAPb I_3-xBr_x/PM6:Y6(x=0,1,2,3)),and the interface dynamics of the integrated device is analyzed.In MAPb I_3-xBr_x,different I/Br ratios are used to adjust the energy level of the perovskite and improve the energy transmission performance of interface between the perovskite layer and the organic layer.The results show that:(1)The MAPb I_3-xBr_x/PM6:Y6 integrated cells can broaden the absorption spectrum of perovskite materials to 950 nm,increase the utilization of near-infrared light,and thereby increase the short-circuit current density of the cells.(2)Compared with perovskite solar cells,among the four integrated solar cells,photovoltaic cells based on MAPb I₂Br/OPV and MAPb IBr₂/OPV interfaces have increased current density,resulting in the photoelectric conversion efficiency increased from 5.72%and 3.16%to 7.67%and 5.23%,respectively,while the performance of other cells not improve due to problems such as energy level mismatch or serious charge recombination.