Research On Interface Modification And Composition Control Of Perovskite Solar Cells

The rapid development of the economy requires a large amount of energy demand,which has led to a sharp shortage of traditional energy sources,rising prices,and the environment has also been deteriorated.However,the development of new energy can solve this problem very effectively.Solar cell devices which can convert light directly into electricity by utilizing the photovoltaic effect have attracted more and more attention.Compared with traditional silicon-based solar cells,perovskite solar cell has been considered as the most promising solar cells due to its high efficiency,low cost,and easy preparation.According to the latest report,the highest efficiency of perovskite solar cells has reached 23.6%.However,the poor stability and high Pb content are two main obstructs hindering its large-scale commercialization process.In view of the above problems,To improve the stability of perovskite solar cells,a hydrophobic layer of tin phthalocyanine?SnPc?film was prepared on perovskite by spin coating method,and CaBr₂ has been employed to dope the CsPbBr₃ perovskite by a two-step method to reduce the content of toxic lead in this thesis.Main contents and results are summarized as follows:Tin phthalocyanine?SnPc?film was used as a hydrophobic interface modification layer,which has prepared on the surface of the perovskite by solution spin coating.It can be seen in SEM that the tin phthalocyanine?SnPc?film was successfully prepared on the perovskite,which is beneficial to the later film growth preparation.The uniform hydrophobic SnPc film can effectively blocking moisture into the perovskite as shown in the hydrophobic angle and atomic force microscopy?AFM?test;photoluminescence spectroscopy and impedance spectroscopy?EIS?test results show that the carrier transport was enhanced and recombination of electrons and holes was reduced of perovskite modified by SnPc;photovoltaic performance tests show that photoelectric conversion efficiency was enhanced based on FTO/TiO₂/MAPbI₃/SnPc/Spilo-OMeTAD/Au;The photoelectric conversion efficiency?PCE?of perovskite solar cell is 13.2%from 15.62%modified by SnPc,and the device still can maintain 86%high stability efficiency under the environmental condition of?25°C,relative humidity RH=30%?for 90 days.However,the long-term photoelectric conversion efficiency of the unmodified solar cell only maintained a 10%of the initial efficiency after 60 days.The inorganic perovskite CsPbBr₃ film was prepared by two-step method,and the Pb content was reduced by doping CaBr₂.The perovskite grain was promoted doped by a content of Ca²⁺as shown by scanning electron microscopy?SEM?.X-ray photoelectron spectroscopy?XPS?test and electron probe?EPMA?explain that Ca²⁺is successfully doped onto perovskite and uniformly distributed on the surface of perovskite;and the surface roughness of perovskite doped by Ca²⁺can reduced as indicated from atomic force microscopy?AFM?;Photovoltaic performance tests show that CsPbBr₃ perovskite solar cell devices based on different Ca²⁺doping have different photoelectric conversion efficiencies and exhibit optimal performance at 5%Ca²⁺content,and the photoelectric conversion efficiency PCE=8.16%based on 5%Ca²⁺doping,which is 13%higher than that of the original perovskite solar cell PCE=7.21%.