| The chlorophyll as one kind of porphyrin compounds can be widely found in the nature. It has a wide absorption band in the ultraviolet visible light range due to its π conjugate ring structure. The chlorophyll plays a role in capturing and transfering light energy in the photosynthesis of green plants. In this paper, Based on the unique molecular structure and photoelectric properties of the chlorophyll, chlorophyll derivatives as dyes were used to build dye-sensitised solar cells(DSSC), and the photoelectric performances were investigated in this paper.The chlorophyll was extracted from bamboo leaves and modified to obtain Chl-Mg Na, and the photoelectric and electrochemical properties of Chl-Mg Na were investigated in this paper. The results showed that Chl-Mg Na has strong absorption in ultraviolet visible light range, the ground state and excited state energy levels of Chl-Mg Na meet the requirements of the DSSC for the energy levels of dyes. Chl-Mg Na as dye was used to assemble DSSC, and the sensitized conditions of the dye concentration, p H value, temperature and so on were optimized. Sensitized electrode was prapared under the optimal conditions with the silver foil as the background of the cells to obtain the highest photoelectric conversion rate, Up to 0.44%. Chl-Mg Na and chlorophyll structure was optimizated using quantum chemistry calculation. The result shows that the carboxyl group makes Chl-Mg Na easy to be adsorbed to the surface of Ti O2.Mg2+ ions in Chl-Mg Na was replaced by Zn2+ to obtain Chl-Zn Na derivatives. The investigation of the photoelectric and electrochemical properties of the derivatives shows that there are great effects of the central metal ions on the electronic absorption spectra, fluorescence emission spectra and fluorescence quantum efficiency. Different central metal ions derivatives have different ground state potential and excited state potential. Photoelectric test shows that the photoelectric conversion rate of the zinc derivatives was the highest, up to 0.552%. Based on the analysis of the molecular frontier orbital, it was speculated that the different central ion radius will be responsible for the difference of conjugated porphyrins, and excited state electron delocalization, affecting the photoelectric properties of derivative fluorescence quantum efficiency of the cells。Chl-Mg Na was modificated to prepare 3 kinds of manganese chlorophyll derivatives. The results of quantum chemical calculation and fluorescence test showed that the manganese chlorophyll derivatives have strong fluorescence and their photoelectric conversion rate can up to 2.3 times higher than that of chlorophyll-Mg Na. The photoelectric performance of Chl-Mn H is better than that of Chl-Zn Na though the electron cloud delocalization of Chl-Mn H is poor than that of Chl-Zn Na according to the graph of molecular frontier orbital. The photoelectric performance has a close relationship not only with the electron clouds delocalization of the derivatives but also with the electron number on 3d orbital of the centre metal ions. Additionally, the effects of solvents on the performances of photoelectric cells were systematically investigated. In this paper, the CH2Cl2 is an idea solvent to obtain the best photoelectric properties. |
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