【作者】 郭福安；

【导师】 张伟风；

【作者基本信息】 河南大学 ， 凝聚态物理， 2010， 硕士

【摘要】 随着全球变暖,大气污染问题日趋严重化以及常规能源供应耗尽,开发和利用可再生绿色能源已成为人类社会所面临的重大课题。今天,太阳能发电被广泛认为是一种可持续增长的、绿色可再生的能源技术,而太阳能电池已经渐渐应用于各种各样的领域,从消费电子、小尺度分布式系统到兆瓦规模的集中火力发电厂都能发现它的存在。目前,太阳能电池是以固态光伏电池为主导的。以后太阳能电池将会向低廉高效的方向发展,染料敏化太阳能电池(Dye-Sensitized Solar Cell, DSSC)则正是因为这样的优势而获得了广泛的关注。虽然这种电池已经具有适度的光电转化效率,可是仍有许多方面需要进一步改进,比如电子的传输以及光吸收范围等。自从瑞士洛桑联邦理工学院的Gr?tzel教授发明了这种由染料拓宽半导体纳米多孔薄膜光吸收范围的太阳能电池之后,许多的学术以及商业研究机构都对其产生了很大的兴趣并投入了大量的资金与精力去提高其效率以及组装电池的更好方法。尤其是在之后的6年中,Gr?tzel教授的小组得到美国国家再生能源实验室(NREL)的证明将其电池效率提高至10%。染料敏化太阳能电池一般是由纳米晶氧化物半导体做成的薄膜电极,染料敏化剂,电解液,对电机以及透明导电衬底组成。具有代表性的就是将二氧化钛薄膜作为电池阳极,铂电极作为对电极,然后加入溶于有机溶剂的I3?/I?溶液作为电解液,这样就组成了一个具有三明治结构的DSSC。由于具有廉价,市场资源充足,无毒,生物相适性,并且可以大规模用在保健品以及绘画颜料上,TiO2是作为DSSC阳电极材料的最佳选择。但是二氧化钛也有很大的光催化性质,有可能分解染料,因而有出现了很多关于其它材料的报道。以前的对工作电极材料的研究都只是针对二元氧化物,比如TiO2,ZnO,SnO2,Nb2O5和In2O3。相对而言,多元氧化物很少有人研究过。据我们所知仅仅的报道只有SrTiO3和最近的Zn2SnO4。与二元氧化物相比,多元氧化物的材料具有更自由的条件去调节材料的化学和物理性质,接着通过这种对其性能的改变而寻找到最适合作为电池工作阳极材料。本文通过利用不同方法制备BaSnO3颗粒并测试其形貌和光学性质,研究了不同制备方法对物质的性质的影响。通过表面光电压和将其作为工作电极组装成染料敏化太阳能电池,研究了不同制备方法的BaSnO3颗粒性质之间的差异和电池不同效率之间的关系,并得到了1.1%的光电转化效率。主要作了以下有意义的工作:1.分别使用共沉淀,水热和固相三种方法制备出颗粒大小在0.1-1.1μm范围内的BaSnO3颗粒,分别利用X射线衍射,扫描电子显微镜,比表面积仪,拉曼光谱研究其结构与形貌情况,并研究了其敏化前后的表面光电压特性曲线。其结果显示共沉淀法制备的BaSnO3样品具有最好的光电效应并且与N719具有最好的相互作用有可能做成敏化太阳能电池。2.分别以三个不同方法制备的BaSnO3样品为原料,加入水、分散剂后进行研磨,把所得的浆料涂敷在导电玻璃上成膜,550 oC热处理30 min后,在N719染料的乙醇溶液(5×10-5 M)中浸泡24 h,得到BaSnO3/染料电极。用夹子把BaSnO3/染料电极和镀Pt的对电极夹紧,在两者之间滴加电解液,即完成染料敏化太阳能电池的制作。并使用CHI660电化学工作站测试电池的光电转化性能。得到1.1%的光电转化效率。3.通过改进后的水热法制备出具有菱形十二面体结构的BaSnO3颗粒,并利用X射线衍射,扫描电子显微镜,,拉曼光谱,红外光谱研究其结构与形貌情况。其结果当温度上升至240 oC时得到所需结构,其颗粒大小也由240 oC时的10μm长大到270 oC时的15μm。当温度上升到280 oC时,颗粒大小突然降至4μm。探测各个温度所得样品时的紫外可见吸收和表面光电压性质,我们发现控制BaSnO3颗粒的大小可以改变其表面光电压性质。更多还原

【Abstract】 Due to global warming and a depleting natural gas supply, there is a need to find alternative energy sources. Solar electricity is a steadily growing energy technology today and solar cells have found markets in variety of applications ranging from consumer electronics and small scale distributed power systems to centralized megawatt scale power plants. Solar energy conversion is dominated by expensive solid-state photovoltaic cells. As low-cost cells continue to develop, the dye sensitized solar cell (Dye-Sensitized Solar Cell, DSSC) has generated considerable interest as an efficient alternative. Although already moderately efficient, this cell offers numerous areas for improvement, both electronically and optically.Since Professor M. Gr?tzel in EPFL introduced the nanoporous films into dye-derived wideband semiconductor research and made the breakthrough in the photoelectric conversion efficiency of dye-sensitized solar cells, academic and commercial interests have been paid on DSSCs for their high efficiency, their potential low-cost and simple assemble technology, especially in the past 6 years since Gr?tzel and his group team at EPFL were able to demonstrate the first 10% efficient cells certified by NREL in USA. Dye-sensitized solar cell is composed of nanocrystalline semiconductor oxide film electrode, dye sensitizers, electrolytes, counter electrode and transparent conducting substrate. Typically, dye-derived nanocrystalline titania films were used as photoanode, platinized counter electrode, filled with electrolyte solution of I3?/I? in organic solvent, then the sandwiched solar cells are formed. Due to low-cost price, abundance in the market, nontoxicity, and biocompatiblity, and as it is also used widely in health care products as well as in paints, TiO2 becomes the best choice in semiconductor till now. But, some semiconductors have been applied to built new structures and avoid the oxidation of dye. Previous research has been limited to simple binary oxides, including TiO2, ZnO, SnO2, Nb2O5 and In2O3. In contrast, the application of multication oxides has been rarely explored. To our best knowledge, the only reported ternary oxides are SrTiO3 and s Zn2SnO4. In comparison with simple binary oxides, multication oxides have more freedom to tune the materials’chemical and physical properties by altering the compositions.Different preparation methods including coprecipitation, hydrothermal and solid state reaction are employed to synthesize BaSnO3 particles to optimize the photoelectric activities of electrode materials. The photoelectric properties of BaSnO3 particles and the performances of DSSCs are investigated by surface photovoltage spectroscopy and current–voltage measurements. The light-to-electricity conversion of 1.1% is preliminarily reached on the DSSC made of the coprecipitation-derived BaSnO3 particles.1. Different preparation methods including coprecipitation, hydrothermal and solid state reaction are employed to synthesize BaSnO3 particles to optimize the photoelectric activities of electrode materials. Which have a size distribution in the range of 0.3-1.1μm. The cell of coprecipitation-derived BaSnO3 particles exhibits the best photovoltaic performance, which is attributed to sufficient dye adsorption and good electronic interaction between BaSnO3 and dye. The results suggest that the controlling synthesis process would be a key strategy to apply appropriate material for dye-sensitized solar cells.2. The BaSnO3 film was obtained by scraping method. BaSnO3 slurry was prepared by grinding the mixture of BaSnO3 powder water, dispersant acetylacetone and Triton X-100. Then the slurry was scraped on the conductive glass plate. The BaSnO3 film was heated at 550 oC for 30 min to remove some impurities and produce nanoporous. BaSnO3 /dye electrode was fabricated by immersing the nanoporous BaSnO3 film into dye N719 solution(5×10-5 M)for 24 h. The cell was assembled by dropping an electrolyte solution into the space between the BaSnO3 /dye electrode and the counter eletrode. Then the performance test was carried on electrochemical workstation CHI660. The light-to-electricity conversion of 1.1% is preliminarily reached on the DSSC made of the coprecipitation-derived BaSnO3 particles.3. BaSnO3 grains with the shapes of rhombic dodecahedron have been synthesized via a facile modified hydrothermal approach. The crystallization behavior and the morphology evolution of the sample during heating treatment have been studied with the X-ray diffraction, scanning electron microscopy, Raman scattering and Fourier transform infrared spectroscopy. The sample with the single-phase of BaSnO3 can be obtained at the hydrothermal temperature of 240 oC, and the grain size of the product grows with increasing temperature from 10μm to 15μm before 270 oC. But, the grain size was decreased sharply to 4μm when the temperatures at 280 oC. The ultraviolet-visible absorption spectroscopy and surface photovoltage spectroscopy analysis indicated that controlling the size and shape of perovskite oxides is of great importance in photophysical properties of BaSnO3 powder.更多还原