Study On The Fabrication Of Bismuth And Tin-based Perovskite Solar Cells And Performance

Nowadays,the demand for clean and renewable energy has being driven the development of photovoltaic technology.Organic lead halide perovskite solar cell is considered as a very promising photovoltaic technology.Research about lead-based perovskite solar cell has gained remarkable achievements,however,the toxicity of lead may limit its commercial production and large-scale applications.Thus,it is necessary to develop new environmentally and friendly lead-free perovskite materials.This thesis developed MA₃Bi₂I₉（MBI）and FASnI₃ perovskite materials as light absorbers for solar cells.We study the preparation technology and photoelectric properties with tese two materials.In this thesis,main study includes the following two aspects:1.MA₃Bi₂I₉ perovskite layer was deposited on a mesoporous TiO₂ film through interdiffusion of solution-processed BiI₃/MAI stacking layers,resulting in high homogeneousity and coverage,and higher power conversion efficiency in the perovskite solar cell as compared with that prepared using a conventional one-step solution method.The morphology of film is influenced by the concentration of MAI,when the concentration of MAI is 6 mg/mL,the coverage and crystalline of film is best,as evidenced by both the SEM and XRD,and the highest photoelectric conversion efficiency（PCE）of 0.27%.the open circuit voltage(V_oc)is 604 mV,short circuit current density(J_sc)is 1.06 mA/cm² and fill factor（FF）is 0.43.is achieved,which is about twice higher than that from the one-step method device.Different scanning speed and direction J-V curves almost overlap.The results demonstrated that the two-step device had ignorable hysteresis behavior.2.We use SnI₂ and SnF₂ respectively as Sn source to prepare lead-free FASnI₃perovskite film as the active layer in the mesoporous structure of the solar cell device.Using SnF₂ instead of SnI₂ can improve the crystallinity of perovskite.After the heat treatment,FASnI₃ perovskite formed,corresponding to orthorhombic structure and orientation.The results demonstrate that heat treatment can remove the FAF by-product.The photoelectric conversion efficiency（PCE）of perovskite solar cell is influenced by the temperature and time of heat treatment.When excessive SnF₂ as source of tin,adding a little tin powder,heating at 135℃for 30 min,solar cell device photoelectric conversion efficiency（PCE）is 2.60%,V_oc is 259 mV,J_sc is20.66 mA/cm² and FF is 0.49.Different scanning speed and direction J-V curves almost overlap.The results demonstrated that the two-step device had ignorable hysteresis behavior.