【作者】 刘广辉；

【导师】 韩宏伟；

【作者基本信息】 华中科技大学 ， 光学工程， 2013， 博士

【摘要】 介观(Mesoscopic)是介于宏观与微观之间的一种体系。作为一种典型的介观太阳能电池,自1991年瑞士洛桑联邦理工学院(EPFL) Michael Graetzel教授报道以来,染料敏化太阳能电池(Dye-sensitized solar cell, DSSC)受到广泛关注并获得了飞速的发展。迄今为止,其器件的最高光电转换效率己超过15%。该太阳能电池具有简单的制备工艺、低廉的材料价格、优越的性能等优点,因此被认为是新兴的第三代太阳能电池。世界各国众多科研单位和公司都给予了大规模的资金投入和技术研发,显示出该类太阳能电池所具有的广阔市场前景。DSSC由光阳极、电解质及对电极组成。其中对电极是DSSC的重要组成部分,其导电性能和电化学性能将决定DSSC器件的内阻,从而影响器件的最终光电转换效率。目前,铂电极已被广泛研究,但是对于低成本的非铂类对电极材料的研究仍处于起步阶段,特别是对于不同类型的非铂类材料之间制备复合电极的研究尚少,有待进行进一步的研发和优化。基于对电极中存在的问题,本论文以廉价碳材料为基础,研究了不同碳材料之间混合比例对于单基板DSSC中介孔碳电极性能的影响,并讨论了痕量铂颗粒修饰对于单基板DSSC碳电极性能的影响。同时,对于非碘电解质,本文采用石墨烯修饰介孔碳材料制备了高效的对电极。此外,本文还研究了导电聚合物对于介孔碳电极性能的影响,并开发了一系列新型的过渡金属-导电聚合物修饰介孔碳材料作为DSSC的对电极。本论文的主要内容为：首先,基于单基板DSSC对于对电极材料的特殊要求,采用高催化性的纳米碳黑和高导电性的片状石墨混合制备了高效的电极材料,并通过调节两者之间的比例,使介孔碳电极综合性能达到最优。同时,研究了单基板DSSC电池中Ti02光阳极厚度和导电玻璃基底对于电池器件性能的影响。其次,针对高性能单基板DSSC中介孔碳电极催化性能不足的问题,采用热分解含铂前驱液的方法制备了披铂碳电极,并通过对其电化学性能的测试、分析,精细的调整了披铂碳电极中铂含量,达到优化电极催化性能的目的。探讨了不同的对电极厚度对于电极电阻、催化性能以及单基板DSSC器件性能的影响。通过优化,液态单基板DSSC电池器件获得7.61%的转换效率。再次,利用化学还原的方法制备了石墨烯材料,并通过静电自组装的方法制备了石墨烯改性的介孔碳电极。通过XRD、拉曼、红外光谱等分析手段表征了石墨烯的还原程度。同时,通过电化学分析,研究了石墨烯改性介孔碳电极对有机硫电解质催化性能的影响。通过优化石墨烯含量,基于有机多硫电解质双基板DSSC的光电转换效率达到6.55%。随后在第五章中,采用化学聚合的方法分别将三种导电聚合物(聚苯胺、聚吡咯、聚噻吩)包裹在介孔碳电极表面。通过电化学测试,分析了不同聚合物修饰介孔碳电极催化活性的差异。探讨了聚吡咯的含量对于电极催化性能和DSSC电池性能的影响。最后在第六章中,采用化学还原的方法制备一种全新的过渡金属(Fe,Co,Ni)-聚毗咯修饰的介孔碳电极。通过电镜、红外和XPS分析了聚吡咯的聚合状态和过渡金属原子的价态,探讨了过渡金属与吡咯之间的成键结构和催化活性位点。通过电化学测试,分析了不同过渡金属-聚毗咯修饰介孔碳电极之间催化性能的差异,及其对于DSSC电池器件性能的影响。更多还原

【Abstract】 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.更多还原