Research On Perovskite Solar Cells Based On Tin Oxide-based Electron Transport Laye

Perovskite solar cells（PSCs）are one of the most promising new types of photovoltaic cells.After a short period of development,their photoelectric conversion efficiency（PCE）has rapidly increased to 25.7%.In the research of PSCs,a lot of evidence shows that excess/residual lead iodide affects the performance of PSCs.The photoinstability of lead iodide itself causes decomposition reactions and reduces the stability of the device.This paper adopts a combination of theoretical research and experimental improvement to improve the efficiency and stability of perovskite solar cell devices and explores the influencing mechanism of performance improvement.The main research contents of this paper include the following points:（1）This paper systematically studies the excess/residual lead iodide in perovskite films.Generally speaking,residual lead iodide mainly comes from incomplete conversion of lead iodide in film preparation process,mismatched stoichiometric ratio of inorganic salt and organic salt in precursor solution and degradation of perovskite materials.At the same time,this paper also discusses various characterization techniques of lead iodide in perovskite films and its mechanism of affecting performance,and summarizes the regulation methods of lead iodide.（2）This article uses a stripping technique to successfully strip the bottom surface of the perovskite layer and observe the distribution of Pb I₂ at the buried interface.It proposes a strategy for doping ammonium halides with Sn O₂,which not only improves the interface contact between the electron transport layer and the perovskite layer but also regulates the residual Pb I₂ at the bottom interface,greatly improving the light stability of the solar cell device.（3）This article further proposes an improved strategy for doping mixed A-site cation halides（FAI-Cs Br）into Sn O₂.Through this strategy,harmful residual Pb I₂ near the buried interface can be converted into an intrinsically stable FACs system perovskite.The addition of Cs⁺balances the lattice strain caused by MA⁺near the buried interface,eliminates residual tensile stress in the bottom region,suppresses the transformation of perovskite fromαphase toδphase,and improves the phase stability of the solar cell device.Finally,the perovskite solar cells and modules achieved power conversion efficiencies of 24.26%and 20.97%,respectively.These PSCs maintained 94.7%of their initial efficiency after operating under sunlight for 1000hours.