| One of the main approaches to utilizing solar energy is converting it to electric energy. As a new member in the solar cell club, dye-sensitized solar cells (DSSCs) have attracted considerable attention in scientific research and practical applications due to the advantages of high conversion efficiency, low cost and simple preparation. As the key component in DSSCs, sensitizers have the responsibility to harvest solar energy. As the Photosynthesis center, porphyrin owns the unique advantage in light harvest and energy conversion. In this thesis, various numbers of triphenylamine and trimethoxyphenyl groups are introduced to the porphyrins as electron donors, and 4-ethynylbenzoic acid is selected as the electron-acceptor group. Thus, several novel porphyrin dyes with D(n)-p-A structure were designed and synthesized as sensitizers for DSSCs, and their structures were characterized by 1-NMR, MS and FT-IR. Their photophysical and electrochemical properties are also investigated. The result demonstrates that the HOMO-LUMO energy gaps remain almost constant irrespective of the donor groups, thus, the variation of the donors significantly affect the HOMO and LUMO values. Under simulated AM1.5 irradiation, the overall conversion efficiencies (η) of the DSSCs based on these dyes lie in the range of 2.70-5.45%, and the zinc porphyrin with two triphenylamine units and one trimethoxyphenyl group as the electron donors (M3T2P) shows the optimized performance. As we all known, the electron injection and dye regeneration processes predominate the overall conversion efficiency. The highest efficiency was achieved by M3T2P because the electron injection and dye regeneration processes are both effective due to the optimally balanced HOMO and LUMO energy levels. In addition, M3T2P has the longest electron lifetime, which is consistent with the highest V∝value. The results are beneficial for the design of efficient DSSC sensitizers by the variation of the donor groups. |
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