The Application In Solar Cells Of The Layered Organic-inorganic Hybrids?C₆H₅C₂H₄NH₃?₂?CH₃NH₃?_m-1Pb_mI_3m+1?m=1,2,3?

As the conventional fossil energy resources report an emergency frequently,renewable energy research and development has become the focus of the whole world.Solar cells that convert solar energy into electrical energy have garnered great attention in recent years.Recently the power conversion efficiency?PCE?of CH₃NH₃PbI₃-based perovskite solar cells has rapidly increased to 20%over the past years.However,the perovskite solar cells have poor stability and a short service life because the perovskite layer is easy to degradation when in contact with moisture,oxygen and UV-light.The two-dimensional organic-inorganic perovskite-like hybrids with the general formula?C₆H₅C₂H₄NH₃?₂?CH₃NH₃?_m-1Pb_mI_3m+1(abbreviated as?PEA?₂?MA?_m-1Pb_mI_3m+1;m=1,2,3)have attractive optical,electronic properties and easy energy band structural tunability.Consequently,in this paper the hybrids?PEA?₂?MA?_m-1Pb_mI_3m+1 were successfully synthesized by a solution method.The hybrids films were also prepared and be applied to perovskite solar cells.The effect of the number of Pb-I sheets in each inorganic layer on the optical absorption properties and energy band structure of?PEA?₂?MA?_m-1Pb_mI_3m+1m+1 was investigated.The effect of the different structure of ETL and the number of Pb-I sheets in each inorganic layer on the photovoltaic performance of perovskite solar cells was also investigated.?1?The?PEA?₂?MA?_m-1Pb_mI_3m+1?m=1,2,3?were synthesized by a solution method.The effect of the excess methylammonium iodide in the reactants on the structure of the hybrids is investigated.Results show that the number Pb-I sheets in each inorganic layer of the hybrids can be effectively tailored by adjusting the methylammonium iodide amount.The best raw material mole ratio with PEAI,MAI and PbI₂ were 2:1,2:2:2 and 2:4:3 for the three hybrids.The resulting hybrids?PEA?₂?MA?_m-1Pb_mI_3m+1?m=1,2,3?possess a typical layered perovskite structure.The three hybrids display reduced bandgaps with increased thickness of the inorganic layers.?2?Hybrid?PEA?₂?MA?_m-1Pb_mI_3m+1?m=1,2,3?films were synthesized by solution deposition method.The effects of the number of inorganic layers on the structures,the arrangement on substrate,morphologies,band energies and the stability to atmosphere.The results indicate that the coverage of hybrid films on substrate is perfect and the stability to atmosphere is very good.The growth arrangement for hybrid films on substrate is that?PEA?₂PbI₄ and?PEA?₂?MA?Pb₂I₇ grow parallel to the substrate plane,while?PEA?₂?MA?₂Pb₃I₁₀ grow vertical to it.The band gaps of these three hybrids are 2.34eV,2.06eV and 1.88eV,respectively.The band energies of?PEA?₂?MA?Pb₂I₇ and?PEA?₂?MA?₂Pb₃I₁₀ are perfectly matching to that of TiO₂ and Spiro-OMeTAD.?3?Hybrids?PEA?₂?MA?_m-1Pb_mI_3m+1?m=2,3?films can be used as perovskite solar cell absorber due to their high surface coverage,appropriate band structure and stable structure.Consequently,in this paper the hybrids films were prepared and be applied to perovskite solar cells.The effect of the structure of electron transport layer,thickness of TiO₂ nanorods and the number of Pb-I sheets in each inorganic layer on the photovoltaic performance of perovskite solar cells was also investigated.The results indicate that the power conversion efficiency increases with the increased the number of inorganic layers.Finally,the planar heterojunction and mesoscopic architecture perovskite solar cells were obtained the optimal properties with PCE of 1.62%and 3.72%,respectively.The usage of TiO₂ nanorods effectively increase the J_sc.The J_sc,V_oc and PCE increased firstly and then decreased with increasing nanorod length.In addition,the repeatable and stable perovskite solar cells were prepared with?PEA?₂?MA?₂Pb₃I₁₀ absorber and 500nm-long TiO₂ nanorods.