Research On Fabrication And Stability For Two-Dimensional Ruddlesden-Popper Perovskite Solar Cell

The organic-inorganic perovskites have potential application prospects in optoelectronic devices,owing to their unique properties,such as strong optical absorption,long charge-carrier diffusion lengths,and high defect tolerance.The power conversion efficiency based on the perovskite solar cell have increased from 3.9 to 25.2%in just over 10 years,which attracted tremendous attention.However,the traditional 3D perovskite solar show a poor stability under humidity,thermal and continuous light,which limits the commercial development of perovskite solar cell.Recently,2D Ruddlesden-Popper perovskite materials have obtained higher stability due to unique structural properties,which has widely favored by researchers.This matertial consists of large organic spacer cations and smaller organic cations,show a multilayer quantum well structure.The interation between different components will lead to different surface morphology,growth orientation,which directly affect the efficiency and stability of the device.In addition,the phase distribution is quite sensitive to processing conditions.Therefore,how to effectively select space cations to control physical property is an important way to achieve the improvement of the photoelectric characteristics for 2D-RP perovskite solar cells.In this paper,we seek to enhance the stability and efficiency simultaneously by tuning organic components in Ruddlesden-Ropper perovskites?2D-RPPs?.Four groups of 2D-RPPs?PEA?₂?MA?_n-1Pb_nI_3n+1,?FPEA?₂?MA?_n-1Pb_nI_3n+1,?PEA?₂?FA?_n-1Pb_nI_3n+1 and?FPEA?₂?FA?_n-1Pb_n I_3n+1 are prepared by combination with the 4-fluorophenethylammonium?FPEA?,phenethylamine?PEA?and formamidinium,methylamine,to investigated how the FPEA and FA cations influence the properties of films and devices performance.The?FPEA?₂?FA?₈Pb₉I₂₈ film is found to be a strong out-of-plane direction,high crystallinity,high carrier mobility and low defects state density by analyzing the properties of perovskite films with different n values.At the same time,its absorption edge substantially extends in infrared region and greatly increases the photocurrent.Later,the relationship between film parameters and interface defect and device performance was studied by SCAPS software.The results show that the carrier mobility and defect density have a serious effect on the short circuit current density and open circuit voltage of the device.Based on this result,we used the different film parameter obtained from experiment for four n=9 perovskite film to simulate the perovskite devices.The simulation results show that?FPEA?₂?FA?₈Pb₉I₂₈perovskite device with lower defect density and higher carrier mobility can obtain the highest conversion efficiency.The experiment measurement results of the photovolatci parameters of the four perovskite devices also show excellent performance for?FPEA?₂?FA?₈Pb₉I₂₈.Finally,the formal structured?FPEA?₂?FA?₈Pb₉I₂₈ perovskite solar cell prepared by one-step spin coating method achieved a conversion efficiency of 16.15%,with an open-circuit voltage of1.07 V,current density of 20.88 mA/cm²,and fill factor of 72.29%.In terms of stability,both?FPEA?₂?FA?₈Pb₉I₂₈ film and device show an excellent humidity and thermal stability.The film does not change significantly after exposed to 50±10%RH for146 days or annealed at 80?for 120 h.The unencapsulatd device maintains 95%of its stating PCE after 2112 h when stored in ambient air with 30-70%RH,which is even superior than the reported stable?PEA?₂?MA?₈Pb₉I₂₈ and?FPEA?₂?MA?₈Pb₉I₂₈ solar cells.