Effect Of Interface Modification On The Performance Of Perovskite Solar Cells

Perovskite solar cells have attracted a lot of researchers’attention because of its high photoelectric efficiency and low preparation cost.However,the cell devices are not easy to be prepared in the air environment due to the high sensitivity of perovskite to temperature and humidity.The energy level structure matching degree of traditional TiO₂ electron transport layer and perovskite layer is low,so this makes the electron transport encounter a large energy level barrier.TiO₂ also has a certain photo-degradation effect,which promotes the decomposition of perovskite layer.In order to solve the above problems,the method of interface modification was used to improve the film-forming property of perovskite by adding anti-solvents in the process of perovskite crystallization,and the optimal scheme of preparing perovskite solar cells in the air environment was determined.Cs₂CO₃with good electron injection ability was introduced to modify the TiO₂ electron transport layer,and its influence on the photoelectric performance of perovskite solar cells was explored.The research contents of this paper are summarized as follows:In the process of preparing perovskite film under air condition,the influence of different anti-solvents（ethyl acetate,chlorobenzene,n-butanol,and acetonitrile）on the photoelectric performance of perovskite solar cells was studied by dropping different anti-solvents.Acetonitrile accelerated the decomposition of perovskite,but the introduction of other anti-solvent promoted the growth of perovskite grains.Compared with the original perovskite film,the coating modified with ethyl acetate as anti-solvent had higher film-forming quality,higher light absorption intensity,and lower carrier recombination due to the growth of crystal grains.The photoelectric efficiency of the perovskite solar cell modified by ethyl acetate was 9.34%,50%higher than that of the cell device without anti-solvent modification.After 180 hours at room temperature and 55%humidity,its photoelectric conversion efficiency still kept 53%of the original efficiency,while the unmodified cell device had completely failed.Therefore,ethyl acetate was the best anti-solvent material in this experiment.Using ethyl acetate as anti-solvent material,different concentrations of Cs₂CO₃ were innovatively introduced to modify the TiO₂ electron transport layer and its influence on the photoelectric performance of perovskite solar cells was explored.The results show that when the concentration of Cs₂CO₃ was 1 mg/m L,the modification effect on the TiO₂electron transport layer was the best,and the bandgap of TiO₂ was reduced.The optimal photoelectric efficiency of the PSC device prepared by Cs₂CO₃ was 12.9%,which was 38%higher than that of the unmodified PSC（9.34%）and could still maintain 78%of the original efficiency after 250 hours,while the unmodified original device has failed.Cs₂CO₃had a good electron injection ability.The introduction of cesium carbonate enhanced the light absorption intensity of the device,reduced the complex quenching phenomenon of carriers and the work function of TiO₂ electron transport layer from 4.96 e V to 4.58 e V,and made the energy level structure match well with the perovskite energy level and reducing the energy level barrier.