| As a re-new-energy, solar cells have many advantages, such as non-pollution, large reserves, ease of use. There are some special advantages, especially in the roof power plant. They can greatly decrease the network losses. However, the large-scale of solar cells is not applied due to the high cost of production, low conversion efficiency, etc. Therefore, the finding of low-cost, high-conversion efficiency materials possess high real meaning. The dye-sensitized solar cells (DSSCs) are given occasion to tremendous interest and large-scale research in numerous academic laboratories.Due to the unique bonding characteristic and special construction, metal chalcogenides nanomaterials possess many excellent proprieties on electricity, photology, magnetism, etc. This given occasion to tremendous interest and large-scale research in numerous academic laboratories. SnS and SnS2 are crucial mid-band gap semiconductors and nanometer catalysts. Besides, SnSx nanomaterials are considered to have potential application in lithium battery, optical-electronics component, catalyzer, photovoltaic, etc. However, bare SnSx cannot achieve excellent performance in a catalytic reaction. To solve this disadvantage, a composite of SnSx with RGO may be a great choice. As for SnSx and a composite of SnSx with RGO, although the efforts about these respects have been made great advance, there are still many problems to be solved, such as the reunion of grapheme, the effect of catalyst, the microstructure of the composite. Therefore, this thesis aims to investigate the catalytic activities through I-V curves and conversion efficiency tests as the CE in DSSCs based on SnSx nanomaterials and SnSx with RGO nanocomposites.This thesis contains five chapters. The first chapter mainly presents the structures, electricity propriety, photology, and the application in the new energy field. Then we review the latest processes in the photovoltaic, especially for the counter electrodes of dye-sensitized solar cells.In the second chapter, we focused on synthesizing hexagonal SnS2 nanoparticles with perfect crystallinity along the (001) facet by changing the proportion of mixed solvent. We found that hexagonal SnS2 nanoparticles with perfect crystallinity along the (001) facet were prospective material for enhancing the photovoltaic performance of CEs in DSSCs.In the third chapter, a nanocomposite of SnS2 nanoparticles with RGO were synthesized. The effectiveness of this nanocomposite exhibited remarkable electrocatalytic properties upon reducing the triiodide, owning to synergistic effects of SnS2 nanoparticles dispersed on graphene sheet and improved conductivity.In the fourth chapter, the nanosheet-assembled SnS2 microspheres were synthesized through a solvothermal method, and the catalytic activities of the microspheres were investigated by Ⅰ-Ⅴ and electrochemical performance tests as counter electrodes in dye-sensitized solar cells. To further improve the power conversion efficiency of the counter electrode of the microspheres, different amounts of reduced graphene were added into the microspheres by simply physical mixing. With the addition of 6 wt% reduced graphene, the cell performed a higher power conversion efficiency.In the last chapter, we report such a phase transition in which tin (Ⅳ) sulfide is transformed into tin (Ⅱ) sulfide after annealing in an argon atmosphere. The precursor and final product are respectively fabricated together with reduced graphene to form nanocomposites that are subsequently used as the counter-electrodes. It is found that the power conversion efficiency of dye-sensitized solar cell with the counter-electrode made of tin (Ⅱ) sulfide and reduced graphene oxide nanocomposites achieves higher power conversion efficiency than that of a device using tin (Ⅳ) sulfide and reduced graphene oxide nanocomposites as counter electrode. |
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