Effect Of DJ Type Two-dimensional Perovskite On The Efficiency And Stability Of Solar Cells

Organic-inorganic metal halide perovskite（OIHP）solar cells have emerged as outstanding candidates for the emerging photovoltaic industry due to their characteristics of high efficiency and low manufacturing cost.Recently,the power conversion efficiency（PCE）of three-dimensional（3D）perovskite solar cells has rapidly increased from 3.8%to 25.7%,promising to replace crystalline silicon-based solar cells.However,there are still many defects on the surface and in the bulk phase of perovskite,the high defect density is the center of charge non-radiation recombination and channels for ion migration,which affects the efficiency and stability of the device.Therefore,two-dimensional（2D）perovskite can be modified and designed to improve the photovoltaic performance of 3D perovskite by taking advantage of its unique photoelectric characteristics and ultra-high environmental stability.At present,there are few studies on the corresponding application of DJ（Dion-Jacobson）-type 2D perovskite in 3D perovskite interface modification and quasi-2D perovskite direction in the field of perovskite solar cells.Based on the above situation,this paper conducts an in-depth study on the application of DJ-type 2D perovskite in the field of 3D perovskite solar energy,and its related work is as follows:（1）Three organic cations of PMA（RP）,MDMA（DJ）,and PDMA（DJ）were used to modify the upper interface of 3D perovskite,forming 2D/3D perovskite by annealing process.It is found that the modified devices have improved PCE and stability.In addition,2D perovskite formed by MDMA organic cations exhibits double passivation at the interface and grain boundary of perovskite.The good passivation effect inhibits the non-radiative recombination of carriers and increases the PCE of the device from20.26%to 22.01%.In addition,the optical,wet,and thermal stabilities were enhanced,and 2D/3D perovskite formed by MDMA（DJ）and PDMA（DJ）showed stronger stability than 2D/3D perovskite formed by PMA（RP）.The results also show that DJ-type 2D/3D perovskite has stronger environmental stability than RP-type 2D/3D perovskite.（2）Two novel organic cations（MDAN and EDAN）with different angles were used to form a nominal n=6 DJ-type 2D perovskite.It is found that the（EDAN）MA₅Pb₆I₁₉:0.15MACl perovskite device achieved a power conversion efficiency of 13.0%,outperforms the 9.6%PCE achieved by（MDAN）MA₅Pb₆I₁₉:0.15MACl based device.The formation of quasi-2D perovskites with high-n values was observed for both compounds,while the superior performance is demonstrated by（EDAN）MA₅Pb₆I₁₉:0.15MACl based device,which could be attributed to its better film morphology and lower defect density.In addition,the MDAN-based quasi-2D perovskite is concentrated near the surface of the film,resulting in an unsatisfactory arrangement of electron bands,which is not conducive to carrier transport,and thus loss of photovoltaic performance.Finally,the two（MDAN/EDAN）MA₅Pb₆I₁₉:0.15MACl perovskite films remained unchanged for 20days in the air with a relative humidity of 50%.