Preparation And Performance Of CsPbIBr₂ Perovskite Solar Cells

Organic-inorganic hybrid perovskite materials have received extensive attention and in-depth research due to their excellent optoelectronic properties,such as adjustable band,high absorption coefficient,high carrier mobility and long diffusion length.The power conversion efficiency of perovskite-based solar cells has been rapidly improved from 3.8% at the beginning to 25.5% at present,becoming one of the most promising solar cells.However,in the process of perovskite solar cells commercialization,there are still many problems to be solved.Among them,the quality of perovskite film is the key to obtain high performance devices.Therefore,it is very important to obtain the perovskite film with high coverage rate,large grain size,uniform density and no pinhole.In this thesis,the inorganic perovskite material CsPbIBr₂ was selected and based on the structure of FTO/Ti O₂/CsPbIBr₂/Spiro-OMe TAD/Au planar heterojunction solar cells,the device preparation and performance were studied in detail.In this thesis,two methods to improve the film are proposed.First,by introducing the volatile organic salt formamidine acetate（FAAc）into the precursor solution of CsPbIBr₂,the crystal growth process and internal defect state density of inorganic perovskite CsPbIBr₂film were regulated.The optimal device performance was obtained when the concentration of FAAc additive was 40 mg/m L.Compared with the reference devices,the power conversion efficiency of CsPbIBr₂perovskite solar cells based on FAAc regulation is improved by more than 35%,up to 9.44%,and the open-circuit voltage and short-circuit current density are also improved.At the same time,the average power conversion efficiency of the 20 independent devices is increased from 5.77%to 8.31%,and the device efficiency distribution is concentrated,which has better repeatability.The second,a small amount of Zn X₂（X:I,Br,Cl）was introduced into the precursor solution of CsPbIBr₂,and the crystal structure of CsPbIBr₂perovskite was fine-adjusted by replacing part of Pb²⁺by Zn²⁺.This is beneficial to improve the crystallinity of the corresponding film,making its grain size increase and defect reduction.The power conversion efficiency of CsPbIBr₂solar cells doped with 0.5%Zn X₂increased from 6.93%to 8.14%,7.45%and 7.82%,respectively.At the same time,the average power conversion efficiency of their 20independent devices increased from 5.87%to 7.09%,6.44%and 6.60%,respectively,and the device efficiency distribution was concentrated,with good repeatability.