Research On Preparation And Stability Improvement Of Perovskite Solar Cells

With the development of social economy,energy shortage and environmental pollution have more and more impacts on human life.Solar energy,a new type of clean energy,has been vigorously promoted and researched.Among them,perovskite semiconductor materials have the characteristics of bipolar transmission,adjustable band gap,fast carrier diffusion,long diffusion distance,simple preparation process,and low price,which are widely used in the field of solar cells.The photoelectric conversion efficiency of perovskite solar cells has been continuously improved in the past ten years of research.However,while pursuing high photoelectric conversion efficiency,the long-term service stability of perovskite solar cells is currently the most important problem to be solved.This thesis aims to improve the photoelectric conversion performance and stability of perovskite solar cell devices through different strategies including the selection of the structure of the perovskite solar cell,the optimization of the preparation process,and the passivation of the perovskite film.The main contents are as follows:Organic-inorganic hybrid perovskite solar cell is the perovskite system possessing the highest photoelectric conversion efficiency at present.By preparing perovskite solar cells with compact TiO₂ or SnO₂ as electron transport layers,the relationship between photoelectric conversion efficiency and stability of perovskite solar cells with different electron transport layers was investigated.The results show that the SnO₂-based perovskite solar cell has a higher charge extraction rate and a faster charge transfer.Therefore,it is found that there is almost no hysteresis effect from forward scanning and reverse scanning tests.The photoelectric conversion efficiency is higher,and the stability is stronger compare to compact TiO₂ perovskite solar cells.The photoelectric conversion efficiency of the final device reached 22.03%,and it maintained 79% of the initial efficiency after 30 days of dark storage in a dry environment.In order to improve the stability of the perovskite solar cell,selected a suitable functional layer material,CsPbI₃ inorganic perovskite material with better thermal stability and light stability is choosen as the light-absorbing layer.The crystal growth of CsPbI₃ could be regulated by using dimethylamine iodine as an additive and preheating the substrate before preparation.The results show that when the concentration of the perovskite precursor additive is 0.78 M and the preheating temperature is 100?,the perovskite film morphology is the smoothest and densest,and the photoelectric performance is the best.Meanwhile,the process of light absorption,charge transfer and charge collection of the CsPbI₃ light-absorbing layer are efficiently improved,thus improving the performance of the CsPbI₃ perovskite solar cell.Finally,the photoelectric conversion efficiency could reach 17.66% when the all-inorganic perovskite solar cell was fabricated with compact TiO₂ electron transport layer,CsPbI₃ light absorbing layer,Spiro-OMe TAD hole transport layer,and Ag electrode was prepared in a dry environment.In order to improve the photoelectric conversion efficiency of CsPbI₃ all-inorganic perovskite solar cells prepared in air environment,high-performance all-inorganic perovskite solar cells were successfully prepared by using a new cheap 2-bromoterephthalic acid material to passivate the surface of the CsPbI₃ perovskite film.The research results demonstrate that there is no change in the perovskite phase and microstructure by using 2-bromoterephthalic acid passivation.The improved performance of the perovskite solar cell could be explained by that the 2-bromoterephthalic acid passivation at the interface of CsPbI₃/hole transport layer inhibits the recombination of defects in the electron and hole transport process in the perovskite cell,thus enhancing fluorescence emission intensity of the CsPbI₃ film and the electron transport capacity of the TiO₂/CsPbI₃ interface.Finally,photoelectric conversion efficiency of the CsPbI₃ perovskite solar cell reached 12.19%prepared by using better stability carbon as the electrode,and the packaged perovskite solar cell device maintains 83% of the initial efficiency after 30 days of dark storage in the air environment.