Preparation Of Perovskite Thin Films By Vacuum Single Source Thermal Evaporation And Their Solar Cells

In solar cells,an all-solid perovskite solar cell has attracted great attention from researchers all over the world because of its high photoelectric conversion efficiency,simple manufacturing,and low cost.Perovskite material structure has great natural advantages,high carrier mobility;low exciton binding energy;high light absorption coefficient and wide absorption spectrum;bipolar transport of carriers,these advantages make it the most popular photovoltaic material available today.This paper is divided into two parts:The first part studies the preparation of CH₃NH₃PbI₃ thin film.The CH₃NH₃PbI₃ thin film was optimized by annealing with mixed solvent?IPA,DMF?.The results show that the film has larger crystal grains and crystallinity,and the surface of the film is dense and flat after the solvent is vapor-assisted at 120?for 20minutes.The coverage is high and the band gap of the film is 1.58 eV close to the theoretical band gap width.A large area?100cm²?perovskite CH₃NH₃PbI₃ thin film was prepared by vacuum single source thermal evaporation.The results show that the large area perovskite CH₃NH₃PbI₃ thin film prepared by vacuum single source thermal evaporation is dense,uniform,smooth,and has high crystalline.Pb and I elements compared with the ideal stoichiometric ratio of CH₃NH₃PbI₃ thin film,the film band gap is 1.58eV.The CH₃NH₃PbI₃ thin film solar cells with different device structures were prepared by vacuum single source thermal evaporation method.The results show that the forward structure porous TiO₂ skeleton has more pores and can be made by single source thermal evaporation.The perovskite is filled into the interior of the pores,which is conducive to the formation of continuous,dense and flat perovskite film,which makes the film formation process more controllable;the addition of the reverse structure to the Bphen layer can increase the conductivity and increase the collection of electrons by the electron transport layer.And transport,in addition,the Bphen layer can prevent the Ag electrode from penetrating into the PC₆₁BM electron transport layer during the evaporation of the Ag electrode.The traditional three-dimensional structure perovskite solar cell has poor stability,and the use of layered calcium ore material as the light absorbing layer is considered to be one of the most effective methods to prevent the degradation of perovskite solar cells in air.Therefore,the second part of this thesis explores the preparation of a layered perovskite?CH₃?CH₂?₃NH₃?₂?CH₃NH₃?₃Pb₄I₁₃(?BA?₂?MA?₃Pb₄I₁₃)thin film.High-quality,high-crystalline?BA?₂?MA?₃Pb₄I₁₃ crystal powder with high stoichiometric ratio was prepared under atmospheric conditions.?BA?₂?MA?₃Pb₄I₁₃ thin film was prepared by vacuum single source thermal evaporation method.The effects of annealing temperature,annealing time and solvent annealing on the microstructure and optical properties of?BA?₂?MA?₃Pb₄I₁₃ thin film showed that:?BA?₂?MA?₃Pb₄I₁₃ thin film was annealed at 120°C for 20 minutes,The characteristic peaks?060?,?080?,?111?and?222?of?BA?₂?MA?₃Pb₄I₁₃ film are obviously strengthened,the FWHM is smaller,the crystallinity is higher,the surface of the film is dense and flat,and the Pb/I element Compared with the ideal stoichiometric ratio of?BA?₂?MA?₃Pb₄I₁₃,after the annealing time is increased to 25 minutes,tabular particles appear on the surface of the film and pinholes appear,and the surface of the film is rough.After 20 minutes of annealing?BA?₂?MA?₃Pb₄I₁₃ thin film at 120°C with?-butyrolactone solvent steam,the solvent annealing treatment was optimized after the solventless annealing of?BA?₂?MA?₃Pb₄I₁₃thin film.The film crystal particles are further enlarged,the surface of the film layer is more compact,the stoichiometric ratio of Pb and I is 0.36,and the forbidden band width is 1.89eV,which satisfies the ideal stoichiometric ratio and theoretical optical band gap of?BA?₂?MA?₃Pb₄I₁₃.Based on the optimization of?BA?₂?MA?₃Pb₄I₁₃ thin film,a perovskite thin film solar cell with ITO/PEDOT:PSS/?BA?₂?MA?₃Pb₄I₁₃/PC₆₁BM/Ag was fabricated.The current density was 10.38 mA/cm²,the voltage was 0.95 V,the fill factor was 46%,and finally the highest was 4.5%,and the average photoelectric conversion efficiency was 4% without hysteresis.