| As a new generation of solar cells, dye-sensitized solar cells（DSSCs） have attracted great attention for photovoltaic applications because of their simple fabrication procedure, low cost of fabrication, environmentally friendly and high energy conversion efficiency. In general, DSSCs consist of a nanocrystalline Ti O2 film sensitized with light-harvesting absorbers, a platinum（Pt） counter electrode（CE） and a redox electrolyte containing the iodide（I-）/triiodide（I3-） couple. The CE is one of the most important components in DSSCs, collecting electrons from an external circuit and catalyzing the reduction of I3- in the electrolyte. The CE is usually composed of the noble metal Pt because of its high electrocatalytic activity, electrical conductivity, and stability. However, the scarcity and expense of Pt limit its use in DSSCs. Therefore, it is necessary to find alternative CE materials that are inexpensive with relatively high catalytic activity to replace Pt in DSSCs. In this paper, we prepared a series of high efficiency and low-cost CE materials mainly by combining the Cu In S2（CIS） nanocrystals with carbon nanofibers. This thesis includes the following sections:（1） Polyvinyl Pyrrolidone（PVP）, Copper dichloride（Cu Cl2）, Indium trichloride（In Cl3）,Thiourea（C2H5NS） and graphene oxide nanosheets（Go） were used as raw materials for electrospinning. Cu In S2å'Œ GO+Cu In S2 nanofibers were obtained by electrospinning and carbonization process. Further the synthesized Cu In S2 and GO+Cu In S2 nanofibers were used as counter electrodes for DSSCs. The results indicated that Cu In S2 and GO+Cu In S2 counter electrode based DSSC showed 5.27% and 5.93% respectively. The detailed interfaces of these counter electrodes and DSSCs were analyzed by EIS and Tafel measurements for analysis of the power conversion efficiency.（2） PAN, Cu Cl2, In Cl3, C2H5 NS and chloroform（CF） were used as raw materials. CIS/C, p-CIS/C and p-RGO@CIS/C compound nanofibers were fabricated via electrospinning and carbonization. The three kinds of nanofibers were applied to the counter electrode for DSSC. The results showed that p-RGO@CIS/C counter electrode exhibited the best photoelectric conversion efficiency（η= 7.23 %） than those of p-CIS/C and CIS/C counter electrode, even better than the Pt CE（η = 6.34%）, which was attributed to its special hierarchical structure and large specific surface area.（3） A common garbage, egg shell membrane（ESM）, was used as a raw material to fabricate carbonized chicken eggshell membrane（CESM） loaded chalcopyrite Cu In S2 nanocrystals by simple liquid impregnation and carbonization method. The CESM-Cu In S2 composite structure has natural 3-D macroporous network structure, in which abundant Cu In S2 nanocrystals with average size about 25 nm were inlayed in the carbon submicro fibers. The CESM-Cu In S2 counter electrode exhibited a power conversion efficiency of 5.79%, similar to Pt counter electrode. |
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