| Growing global energy consumption,which has resulted in serious environmental issues,is impelling the requests and investigations about clean and renewable energy resources for development of a sustainable society.Solar energy,as a clean and continual energy sources,compared with traditional fossil fuel energy,provides a good choice for the development.Converting solar energy directly into electricity is the most feasible technology.Dye-sensitized solar cells(DSSC),as a new generation of sustainable photovoltaic devices,have attracted extensive attention in view of their low cost,easy processing,and environmental benign property.It is well-known that photosensitizers play a key role in this type of DSSC,in which they catch photons and inject electrons into the conduction band of the TiO2 semiconductor.The highest efficiencies of energy conversion have been achieved by the devices of DSSC using Ru polypyridyl complex and Zn porphyrin dyes as photosensitizers.Porphyrins are the promising biomimetic sensitizers because of their intense absorbing Soret bands(400-450 nm),moderate absorbing Q bands(550-600 nm)and their rigid molecular structures with multiple sites for modification.In order to understanding the relationship between structure and properties about por:phyrin sensitizer,we have designed and prepared some series porphyin dyes,investigated their performance in the following areas:Chapter 1:An overview of the renewable energy resources,solar energy,solar cells,dye-sensitized solar cells and photosensitizers.Chapter 2:Symmetric porphyrinzinc dyes have been devised,synthesized,and performed in dye-sensitized solar cells,in which salicylic acids and azo groups were introduced as a new anchoring group and ?-conjugated bridge via a simple synthetic procedure.The performances of the dyes were investigated by photophysical,photovoltaic,and electrochemical methods.The photoelectric conversion efficiency of their dye-sensitized solar cells has been improved compared with other symmetrical porphyrin dyes.The azo group could be used successfully as a conjugated bridge in sensitizers.The tridentate binding modes between salicylic acid and Ti02 nanoparticles should enhance the interfacial quantum yields of electron injection.Chapter 3:Focusing on the relationship between structure and properties,we designed and synthesized a series of meso-azo-bridged porphyrinzinc dyes.The nitrogen-nitrogen double bonds of azo groups were constructed as ?-conjugated bridges.The performances of the dyes were investigated by optical methods,photoelectric conversion,and density functional theory calculations.We discussed the relationship between ?-conjugated bridge and photovoltaic performance in sensitizers.Chapter 4:Zinc porphyrin dyes attached to ethynyl salicylic acid as an electron transmission and anchoring group have been designed,synthesized,and well-characterized.The performances of their sensitized solar cells have been investigated by optical,photovoltaic,and electrochemical methods.The photoelectric conversion efficiency of the solar cells sensitized by the tridentate dye with salicylic acid as anchoring group demonstrated obvious enhancement comparing with that sensitized by the bidentate dye with carboxylic acid.The density functional theory calculations and the electrochemical impedance spectroscopies revealed that tridentate binding modes could increase the interfacial quantum efficiency of electron injection and collection from dyes to the Ti02 nanoparticles.Chapter 5:To illustrate the operational mechanism between the modification of substituent group in meso-benzene ring and their photovoltaic performance,we designed and synthesized two new zinc porphyin dyes,incorporated two tert-butyl group or octyloxy groups in the meta or ortho positions of each meso-benzene ring,derived from the azo-bridged zinc porphyrin dyes,and investigated their photovoltaic performance and interfacial electron-transfer efficiency of DSSC. |
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