| Due to the low cost, simple production procedure, tunable coloar, flexible property, dye-sensitized solar cell (DSSC) has been recognized as an alternative to next generation solar cells. So far, Pt thin film has been the most commonly used counter electrode in traditional DSSCs. Unfortunately, its high cost, poor stability in corrosive electrolytes, and less reserves hinder its commercial application. In this thesis, different carbon material was composited by MoS2 using microwave-assisted system and electrospinning technique, and used as counter electrodes of DSSCs. The performance of electrodes and cells were investigated. The main contents of this thesis are summarized as followed:1. Carbon microspheres (CSs) were synthesized through a microwave-assisted system and used as counter electrodes of DSSCs. The effects of heat treatment temperature on the stucture and electrochemical performance of CSs counter electrodes were studied. It is found that high temperature heat treatment results in an increase in their carbonization degree and surface area. With large surface area and optimized C/O ratio, CSs treated at 1000℃ shows the best performance at catalysis and conductivity. The cell based on CS1000 counter electrode shows a conversion efficiency of 5.5%. CSs-MoS2 composite film was fabricated by microwave-assisted method and used as counter electrodes. When nanoflake MoS2 particles grow on the surface of CSs tightly, the electrical conductivity and catalysis ability are enhanced. A maximum efficiency of 5.9% has been achieved for the cell based on CSs-MoS2 composite film.2. Nitrogen doped carbon microspheres (NCSs) were prepared through the heat treatment of CSs in an ammonia atmosphere. The relationship between the treatment temperature and nitrogen doping, surface area and electrochemical property of NCSs were studied. NCSs were used as as counter electrodes of DSSCs. It is found that the morphology and nitrogen content of NCSs does not change obviously at different temperature, but the surface area and carbonization degree are highly related to the treatment temperature. Nitrogen-doping can offer more active sites to enhance catalysis ability of NCSs. The cell based on NCS900 counter electrode shows a conversion efficiency of 5.9%. When the nanoflake MoS2 particles composite with NCSs, the performance of composite counter electrode further increases and a maximum efficiency of 6.2% has been achieved.3. Graphene-MoS2 composites were synthesized via one-step microwave assisted chemical bath deposition and used as counter electrodes for DSSCs. The effects of graphene additive amount on the performance of cells were studied. The results reveal that sheet structure graphene and MoS2 particles incorporated tightly, which is benefit of electrical conductivity and catalysis ability. A maximum efficiency of 6.3% has been achieved under 100 mW cm-2 illumination when the Mo:C is 1:1.4. Carbon nanofibers-MoS2 composites were prepared via an electrospinning technique with ammoniumthiomolybdate(VI) and PVP. The effects of thermal pretreatment on the morphology of carbon fibers were studied. The results demonstate that the composite fibers with pretreatment shows a uniform diameter and lots of small size MoS2 particles inside. The adhensin situation of unpretreatment fibers is very serious, which is not benefit of electrical conductivity. A maximum efficiency of 5.7% has been achieved due to the combination of electrical conductivity and catalysis ability from carbon nanofibers-MoS2 composites. |
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