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Alternative TitleThe Preparation of Multi-Shelled Metal Oxide Hollow Microspheres and Their Application in Dye-Sensitized Solar Cells
Thesis Advisor王丹
Degree Grantor中国科学院研究生院
Degree Discipline化学工程
KeywordZno   sno2   多壳层空心微球   染料敏化太阳能电池   光散射
Abstract染料敏化太阳能电池(DSSCs)因为制作工艺简单、成本低廉以及相对较高的转换效率受到了人们广泛的关注。在DSSCs各组成部分中,具有大比表面用于吸附染料的宽带隙金属氧化物半导体薄膜十分关键,通常使用TiO2纳米粒子作为光阳极薄膜材料。但是,与染料受激发后产生的电子快速注入TiO2的速度相比,TiO2其本身的电子迁移速率显得较低,导致了复合的增加,从而降低电池效率。因此,人们尝试其它金属氧化物半导体,如ZnO、SnO2和Zn2SnO4等来替代TiO2。近期,相关文献报道中空结构的ZnO微球作为光阳极材料应用于DSSCs,并取得了4.3%的光电转换效率。所制备的ZnO空心球一方面具有高的比表面可吸附大量的染料,另一方面对可见光有着较强的散射能力,增加了太阳光的利用率。但所取得的效率仍然离人们的期望值较远,需进一步研究提升。本文制备出壳层结构可控的ZnO和SnO2多壳层空心球,作为光阳极材料应用于DSSCs,详细研究了光电性能与多壳层空心球壳层结构之间的关系。主要研究结果如下: (1)利用碳球模板法,通过控制煅烧升温程序,制备出壳层数和壳层间距可控的ZnO多壳层空心球。在煅烧除模板过程中,利用碳球的核壳两部分收缩速率不同来控制产物的空心结构,控制模板的分层是制备最外两壳层相邻的ZnO多壳层空心球的关键。 (2)将所获得的ZnO多壳层空心球作为光阳极材料应用于DSSCs, 光照强度为100 mW?cm–2,研究光电转换性能。结果表明,以最外两壳层相邻的ZnO多壳层空心球(MS-ZnO-HMSs-CDS)薄膜为光阳极的太阳能电池具有较高的光电转换效率,特别是以具有高的比表面和光散射能力的最外两壳层相邻的ZnO四壳层空心球薄膜(4S-ZnO-HMSs-CDS) 为光阳极的太阳能电池,光电转换效率达5.6%。 (3)在ZnO多壳层空心球合成的基础上,以碱处理碳球为模板(ATCMSs)合成了最外两壳层相邻的SnO2多壳层空心球。碱处理碳球的作用在于增加碳球Sn4+的吸附量,并且吸附的Sn4+大部分分布在碳球的外层区域内。 (4)最外两壳层相邻的SnO2五壳层空心球产物具有高的比表面及优异的光散射能力,作为光阳极材料应用于DSSCs后获得了7.18%(TiCl4处理薄膜)的光电转换效率。将其作为散射层置于P25薄膜之上组成组合电池,光电转换效率达到了9.53%,对比相同厚度P25薄膜为光阳极的太阳能电池7.29%的转换效率,提高了近30.7%。
Other AbstractDye sensitized solar cells (DSSCs) have received considerable research interest due to their low cost, simple fabrication process and relatively high conversion efficiencies.The photoanode, which is a mesoporous wide-band-gap metal oxide semiconductor film with an enormous internal surface area for dye adsorption, is one of key features in DSSCs. Typically, TiO2 nanoparticles have been used as the photoanode. However, the ultra-fast electron injection rates from the excited dye into the TiO2 nanoparticles come into conflict with the high electron recombination rates due to low electron mobility and transport properties. Except TiO2, other metal oxide semiconductors such as ZnO, SnO2 and Zn2SnO4 have been recently investigated as promising photoelectrodes of DSSCs. Recently, hollow structure of ZnO with micron sized features are particularly attractive as the photoanodes for DSSCs due to their high surface area to adsorb dye molecules, relatively large size for scattering incident light. However, the reported energy conversion efficiency of DSSCs using ZnO hollow microspheres as the photoanodes is only around 4.3%, which is much lower than that we expected. Here, we demonstrate controllable synthesis of several structures of multi-shelled ZnO and SnO2 hollow microspheres and studied as dye-sensitized solar-cell photoanodes, shell structure-dependent photovoltaic performances of the DSSCs have been investigated in detail. It has mainly the following aspects: (1) By using carbonaceous microsphere as templates, via a simple programmable heating process, we have prepared ZnO hollow microspheres with well-defined structures, in which not only the number of shells but also the inter-shell spacings can be controlled. The key to generating multi-shelled ZnO hollow spheres with close double shells is the split of the outer functional layer from the inner carbon core derived from the differential shrinking rate of both materials under controlled heating conditions. (2) Solar cells utilizing ZnO hollow microspheres as photoanodes were tested under illumination with 100 mW?cm–2 intensity. ZnO hollow microspheres with different shell structures show obvious differences in energy conversion efficiency when used in the dye-sensitized solar cells. We demonstrate that, except for increasing the number of shells, manipulating the inter-shell spacings can remarkably improve the energy conversion efficiency. This is especially true for quadruple-shelled hollow microspheres with close double shells in the exterior and double-shelled hollow core. These have large surface area and the ability to reflect and scatter light and thus show a high energy conversion efficiency of 5.6%. (3) Based on the above, multi-shelled SnO2 hollow microspheres with close double shells in the exterior have been successfully synthesized by using the alkali-treated carbonaceous microspheres (ATCMSs) as the templates. ATCMSs Play an important role in the process, researches show that the adsorption amount of Sn4+ ions in the ATCMS templates is considerably higher than that in the carbonaceous microsphere without alkali treatment, and furthermore most Sn4+ ions are concentrated at the exterior of the carbonaceous microspheres. (4) DSSCs constructed with quintuple-shelled SnO2 hollow microspheres show a high energy conversion efficiency of 7.18% (with TiCl4 treatment) due to the enhanced light-scattering effect and the large specific surface area. Furthermore, an efficiency of 9.53% is achieved for DSSCs with a 5S-SnO2-HMSs-CDS scattering layer on the top of P25 film, representing an increase of 30.7% compared to the cell only based P25 film (7.29%).
Document Type学位论文
Recommended Citation
GB/T 7714
董正洪. 金属氧化物多壳层空心球的制备及其在染料敏化太阳能电池中的应用[D]. 中国科学院研究生院,2013.
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