| In the past ten years,perovskite solar cells（PSCs）,as a high-efficiency and low-cost photovoltaic power generation technology,have received extensive attention from all over the world.The photoelectric conversion efficiency has exceeded 25%from 3.8%in just over ten years.In addition to efficiency,the stability of perovskite solar cells is also a constant concern of researchers.For the perovskite material methylamine lead iodine（MAPb I3）studied in this paper,oxygen and moisture in the environment will erode the MAPb I3 perovskite The thin film will greatly reduce the service life of the battery device,and the heavy metal lead decomposed from the thin film will also endanger the ecological environment,and even more seriously endanger personal safety.In this paper,on the basis of traditional MAPb I3 perovskite films,by using different organic cations with large ionic radius to construct two-dimensional/three-dimensional perovskite heterostructures,high-efficiency and stable perovskite solar cells are finally realized.The details are as follows:The two-dimensional/three-dimensional perovskite heterostructure was prepared by introducing phenethylamine iodide（PEAI）with a benzene ring structure,and the thickness of the two-dimensional capping layer was controlled by changing the concentration of PEAI.The layer can improve the stability of perovskite solar cells,and the in-situ growth of the two-dimensional perovskite capping layer acts as a passivation layer,which can effectively eliminate the trap states on the surface of the three-dimensional perovskite thin film,inhibit non-radiative recombination,and be easier to generate holes,thereby increasing the photoelectric conversion efficiency（PCE）of two-dimensional/three-dimensional perovskite solar cells to 18.60%.In order to explore the effect of different molecular rigidity and flexibility on cell efficiency and stability,the benzene ring structure of PEAI was replaced with cyclohexene,that is,2-（1-cyclohexenyl）ethylamine hydroiodide（CEAI）,Taking advantage of its weaker intramolecular interactions,more homogeneous two-dimensional/three-dimensional perovskite films were prepared.Compared with PEAI,the weaker intramolecular interactions of cyclohexene in CEAI could prevent undesirable aggregation,which would produce With more uniform thin films and reduced non-radiative recombination,the perovskite solar cells prepared based on this method achieved efficiencies as high as 19.43%with good repeatability,and the stability of cell devices under natural conditions was greatly improved.By replacing cyclohexene with a flexible alkyl chain that easily disperses into the perovskite lattice,i.e.isopentylamine hydroiodide（PNAI）as the interfacial halide salt,through a simple heat treatment process,the surface of three-dimensional perovskite is Formation of multi-component two-dimensional perovskites with higher n values,as high n value two-dimensional perovskites（n≥3）are more favorable for charge transfer at the interface,obtaining efficiencies as high as 19.89%and lower hysteresis effect The perovskite solar cells,especially the branched structure of PNAI,also endow perovskite with excellent moisture resistance,which can greatly improve the environmental stability of cell devices. |
