Study On Preparation And Performance Optimization Of Perovskite Solar Cells

Perovskite solar cells(PSCs)show good prospects for industrialization due to their advantages of small exciton binding energy,high carrier mobility,strong light-absorbing ability,and large-scale fabrication with the solution-method.However,the current techniques restrict the performance improvement and cost reduction of the cells.The performance of cells can be improved and the costs can be reduced by optimizing the materials composition,solvents,and preparation conditions.Based on this,the dissertation focuses on the conventional CH3NH3PbI3 perovskite solar cells,to optimize the morphology and structure of the electron transport layer,hole transport layer,and perovskite light-absorbing layer.Thus,the optimized cell achieves 12.8%power conversion efficiency(PCE)using the method of one-step solution.In this thesis,the electrical transport behaviors of TiO2 and SnO2 are primarily compared.The SnCl2.2H2O solution has better wettability with the FTO or ITO substrate.Therefore,fewer pinholes are found in SnO2 film with low temperature hydrolysis.Furthermore,the appropriate energy level structure makes SnO2 suitable for electron transporting and hole blocking in PSCs.Owning to this,the PSCs with SnO2 show higher power conversion efficiency(4.03%)than the power conversion efficiency of PSCs with Ti02(3.24%).Secondly,the oxidation techniques of Spiro-OMeTAD and its effects on the performance of PSCs are studied to improve the power conversion efficiency of PSCs.Four oxidation methods are investigated to promote the performance of PSCs with the structure of ITO/SnO2/CH3NH3Pbl3/Spiro-OMeTAD/Ag.The results show that the pure oxygen oxidation of Spiro-OMeTAD precursors leads to the highest efficiency of PSCs and PCE is increased from approximately 4%to 11.02%and FF is increased from 0.21 to 0.48.Finally,the effects of different anti-solvent extractions on the crystallinity,light absorption and morphology of perovskite thin-films are investigated.It indicates that the perovskite thin-film,which is extracted by Ethyl Acetate,has higher crystallinity,larger crystal grains,more uniform distribution size and stronger light absorption compared with these films extracted by other anti-solvents.As a result,the PSC with the perovskite thin film extracted by Ethyl Acetate achieves a maximum PCE of 12.83%.