| Mesoscopic is a system between the macro and micro. As one of the typical mesoscopic solar cells, Dye Sensitized Nanocrystalline Solar Cell (DSSC) has obtained a rapid development and the highest efficiency of which has reached to more than15%now, since been reported in1991by Prof. Graetzel. Due to its simple preparation process, inexpensive raw materials and excellent performance, DSSC has been considered as the new third generation solar cell, which should replace the silicon solar cells in the future. Many companies and Scientific Research Institutes have offered large-scale capital investment and technology research on DSSC, which makes this kind of solar cell a broad market prospects.DSSC is composed of photoanode, electrolyte and counter electrode. The counter electrode is an essential part within DSSC, which will determine the resistance and efficiency of DSSC. The study on Pt counter electrode has been carried out widely for many years. However, there are only a few studies on the Pt-free counter electrode, especially on the mixture of different Pt-free materials. Hence, the study on the counter electrode is indispensable now.Herein, based on low-cost carbon materials, we investigate the effect of the mixture of different carbon materials on the monolithic DSSC. The mesoscopic platinized carbon was developed as the counter electrode for monolithic DSSC. Meanwhile, the graphene was used as modifier to improve the catalytic activity of carbon electrode towards iodide-free electrolyte. Furthermore, we also investigate the effect of the conductive polymer as the modifier on the carbon electrode and invent a new class of carbon supported transition metal-PPy catalysts for DSSC. The main work is listed as following:In the second chapter, based on the special demand of monolithic DSSC, the mixture of carbon black with high catalytic activity and graphite with high conductivity was used as the counter electrode. Through adjusting the ratio between graphite and carbon black, the performance of the counter electrode was optimized. Meanwhile, the effect of the thickness of TiO2and conductive glass on the performance of monolithic DSSC was investigated. In the third chapter, due to the insufficient of the catalytic activity of graphite-carbon black electrode, the Pt was used to modify the carbon materials by thermal deposition. According to the electrochemical testing, the amount of the Pt in the platinized carbon electrode was optimized. After adjusting the thickness of platinized carbon electrode, the efficiency of monolithic DSSC has reached to7.61%.In the fourth chapter, the graphene sheet was synthesized by chemical reduced graphene oxide, and then the graphene modified carbon electrode was prepared by electrostatic self-assembly. The property of the graphene was analyzed by X-Ray Diffraction (XRD), Raman spectrum and FT-IR. According the electrochemical testing, the amount of graphene was optimized and the efficiency of DSSC based on thiolate/disulfide redox couple reached6.55%.In the fifth chapter, the conductive polymer modified carbon electrode was synthesized by chemical polymerization. According to electrochemical testing, the difference of catalytic activity among three conductive polymers was investigated. The affection of the amount of PPy on the catalytic activity of counter electrode and the performance of DSSC was discussed.Finally, a new class of carbon supported transition metal-PPy complex catalysts was synthesized by chemical reduced. The polymerization of PPy and the valence of the transition metal were analyzed by Scanning Electron Microscope (SEM), FT-IR and X-ray Photoelectron Spectroscopy (XPS) and the bonding structure was discussed. The catalytic active of transition metal-PPy-C electrode was investigated by electrochemical testing. |
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