Study On Mechanism Of Degradation And Repairing Technology Of Hybrid Perovskite Material Degraded By Water

With the increasing concentration of carbon dioxide in the atmosphere,the use of renewable energy has become the consensus of all mankind in order to curb climate change.Therefore,it is necessary to vigorously develop new photovoltaic technology with low price.Perovskite solar cell is a kind of new photovoltaic technology with low price,the photoelectric conversion efficiency of which has increased from 3.8%to 25.2%in the past decade.But for a long time,its stability has hindered its practical use.Among many factors affecting the stability of organic/inorganic hybrid perovskite materials,"water"is the most significant.However,most of the studies are based on"humidity".The degradation of various organic/inorganic hybrid perovskite materials by different forms of water such as"liquid water"and"steam"has not been studied in depth.In order to expand the understanding of the mechanism of degradation of organic/inorganic hybrid perovskite materials caused by various"water",and reduce the dependence on toxic non-polar solvents,the following research has been made:1.In this paper,the reaction process of several representative organic-inorganic hybrid perovskite materials(MAPb I₃ and Cs_0.05(FA_0.85MA_0.15)_0.95Pb(I_0.85Br_0.15)₃)with steam and liquid water is systematically studied.The following conclusions are drawn:only when steam condenses to liquid water on the surface of organic-inorganic hybrid perovskite films,the perovskite material degrades rapidly.While only steam participates the reaction,the degradation of perovskite is very slow.2.Controlling the parameters such as the distance between the nozzle and the substrate,the power of the ultrasonic spray process,the temperature of the substrate material and the rate of the liquid supply,the jet of solvent is evaporated before reaching the surface of the perovskite film.In this way,the hole transport layer is prepared with the hole transport material dispersed in aqueous solvent.The realization of this technology extends the selection range of solvents from toxic solvents such as chlorobenzene and toluene to"green solvents"such as water,which was used to disperse hole transport material while producing perovskite solar cells with n-i-p structure.With PEDOT:PSS dispersed in water and isopropanol as hole transport material,the photoelectric conversion efficiency of MAPb I₃ perovskite solar cells with n-i-p structure reached 10.03%,while that of multi-ion hybrid(Cs_0.05(FA_0.85MA_0.15)_0.95Pb(I_0.85Br_0.15)₃)perovskite solar cells achieved 11.2%.3.The physical and chemical properties of various perovskite films degraded by water were further studied by ultraviolet-visible spectroscopy,scanning electron microscope,atomic force microscope,and so on.As the product of the reaction between water and perovskite material,Pb I₂ was determined.The degraded perovskite film with Pb I₂ has a porous structure and can react with MAI to form dense perovskite film.The efficiency of the corresponding perovskite solar cell was greatly improved by the second reaction of the degraded perovskite film with MAI.After repair,the photoelectric conversion efficiency of MAPb I₃ perovskite solar cell with n-i-p structure increased by about 50%,from 10.05%to 14.85%;the photoelectric conversion efficiency of Cs_0.05(FA_0.85MA_0.15)_0.95Pb(I_0.85Br_0.15)₃ perovskite solar cell with n-i-p structure increased by about 56%,from 11.2%to 16.23%.4.Pb I₂ can easily combine with pyridine to form complex,and then react with MAI to form MAPb I₃ overcoming lower energy barrier,which can form uniform perovskite film at room temperature.The photoelectric conversion efficiency of the corresponding perovskite solar cell was increased from 11.2%to 16.06%,by repairing the Cs_0.05(FA_0.85MA_0.15)_0.95Pb(I_0.85Br_0.15)₃ perovskite film degraded by water at room temperature.