| Since the 21 st century,energy has become the top priority of national development strategy.With the highest potential photovoltaic device at present,perovskite solar cells(PSCs)have developed rapidly in the past ten years,its photoelectric conversion efficiency(PCE)have also been reached 25.7%.However,the environmental stability of PSCs still lags behind that of mainstream silicon solar cells,which also restricts the commercial application of PSCs Therefore,how to improve the environmental stability of PSCs has become an urgent problem to be solved.Based on this,a series of new porphyrin metal complexes were designed and synthesized in this paper to modify perovskite films,so as to improve the efficiency and overall stability of PSCs.The thesis consists of the following:The development history of perovskite solar cells,the structure of perovskite crystals,the structure of PSCs,and their working principles are introduced in this thesis.Based on the design of molecular structures,the rencent works by several research groups in improving the efficiency and stability of organic-inorganic PSCs were summarized.Meanwhile,The existing problems in the current work,the research significance,ideas,and research content of this paper are proposed.According to the unsolved problems in the study of PSCs,we designed and synthesized 4-tetraacrylamide porphyrin complex(4-AMMP,M=Ni,Cu,H)and doped in perovskite precursor solution and prepared into corresponding PSCs.The oxygen atom in the amide bond formed a Pb···O bond with perovskite,which was anchored between perovskite crystal boundaries to improve the stability of PSCs.Due to the fact that 4-tetraacrylamide porphyrin complex can self-polymerization in situ between perovskite grain boundaries(GBs)through thermal induction,organic molecules can effectively encapsulate perovskite GBs.At the same time,the extremely strong hydrophobicity of organic materials,this method can greatly improve the environmental humidity stability of PSCs.However,the tendency of 4-tetraacrylamide porphyrin complexes to form polymers that cannot control the degree of polymerization,the efficiency is slightly reduced compared to unmodified PSCs.Through further design of porphyrin molecules,we selected 4-acrylamide porphyrin molecular metal complexes(AMMP,M=Ni,Cu,H)to modify perovskite films.Using in-situ thermal induction method the same,AMMP molecular dimers were constructed between perovskite GBs.After efficiency testing,it was found that AMCuP doped PSCs have the optimal photoelectric conversion efficiency,which is higher than the control group.We have further studied the self-polymerization process inside perovskite and carried out corresponding tests.Finally,through stability testing,it was found that the efficiency and environmental stability of doped AMCuP molecules were higher than those of unmodified PSCs.Although porphyrin modified PSCs with better efficiency and stability have been obtained,the influence of porphyrin molecular configuration on perovskite grain boundaries is still uncertain.To further investigate this problem,the perovskite films were modified by doping a monoamine Cu porphyrin into perovskite films,two porphyrin-based self-assembled supramolecules were successfully prepared between perovskite grains.After annealing,the stacking pattern of the porphyrin skeleton was changed,and a new supramolecular structure(CuP-S2)was constructed in situ.It was found that the amino unit of CuP-S2 is able to significantly change the dipole orientation of the porphyrins,allowing them to form periodic large polarons.The large polaron formed in CuP-S2 with a positive gradient electric field promotes hole transport between perovskite grains and inhibits nonradiative recombination of charge carriers.The optimal efficiency of the CuP-S2-doped device was significantly increased to 24.2% and exhibited excellent environmental stability.Finally,the work done in this paper is summarized and the parts that are still not completed are prospected. |
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