染料敏化TiO2太阳能电池薄膜电极的研制

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	染料敏化TiO2太阳能电池薄膜电极的研制
其他题名	The preparation and research of TiO2 film electrodes of Dye-sensitized Nanocrystalline solar Cells
	王彦明
导师	李新军
	2007-06-08
学位授予单位	中国科学院广州能源研究所
学位授予地点	广州能源研究所
学位名称	硕士
关键词	Tio2薄膜 Pt分布形式 Dscs 载流子分离内建电势
摘要	具有类似于“三明治”结构的染料敏化纳米晶TiO2太阳能电池（DSCs），以其简单的制造工艺、低廉的价格和高的能量转换效率等优点，近十几年来，在国内外获得了广泛的研究，取得了长足的进步。但是，目前电池在封装工艺，能量转换效率和大面积扩大化生产等方面仍需深入研究和优化。提高DSCs的能量转换效率，无疑是最直接的降低DSCs电池成本的有效途径。然而，制约DSCs能量转换效率的因素很多，包括染料的光吸收效率、电子在TiO2电极中的传输以及电解质中氧化还原电对的氧化还原反应速率等。本论文首先采用溶胶凝胶法制备了掺铂量为0.3at%的Pt不同分布形式的TiO2溶胶薄膜，包括：纯TiO2溶胶薄膜、Pt底层分布的TiO2溶胶薄膜和Pt均匀分布的TiO2溶胶薄膜，并对其进行了物理和电化学方面的表征。通过测量TiO2溶胶薄膜的线性伏安曲线和在有无乙醇作为空穴捕获剂存在时的光电流，得出如下结论：相比于纯TiO2溶胶薄膜，底层分布的TiO2溶胶薄膜，由于Pt团簇的大的功函数，将电子束缚在其四周，这样使得Pt底层分布的TiO2溶胶薄膜更容易将热激发产生的电子和空穴有效分离，并且，空穴向表面富集，即存在有大量的空穴富集在TiO2溶胶薄膜表面。用制备的TiO2溶胶薄膜组装成DSCs，发现Pt底层分布的TiO2溶胶薄膜更有利于注入电子的传输，可大幅度的提高DSCs的光电性能，表现在电池的开路电压Voc和短路电流Isc的增大上。由于TiO2溶胶薄膜薄且致密，导致吸附的敏化染料少，DSCs的光电压和光电流信号小。因此，用自制的溶胶于马弗炉中烧结，制备了纯TiO2纳米粉末和掺铂量为0.3at%的TiO2纳米粉末，外加购买的半导体厂TiO2纳米粉末和P25纳米粉末，采用粉末涂敷法制备厚的纳米TiO2薄膜。对半导体厂纳米粉末制备的DSCs薄膜电极进行了结构探索，具体的结构为：在采用粉末涂敷法制备TiO2薄膜前，先在FTO导电面上，分别拉制2层、4层、8层的纯TiO2和Pt-TiO2溶胶薄膜。结构改进后的半导体厂TiO2薄膜组装成DSCs，虽一定程度上减小了DSCs的开路电压Voc，却能够显著地增大DSCs的短路电流Isc，进而将会使得DSCs的整体性能得到大幅度的提高。其中，拉制2层TiO2溶胶薄膜和4层Pt-TiO2溶胶薄膜，能够获得更大的DSCs短路电流Isc，进而获得了更大的电流密度Jsc。用半导体厂纳米TiO2粉末、P25纳米粉末和自制的TiO2纳米粉末直接涂敷到FTO导电玻璃上，纳米粉末与导电玻直接接触，所制备的薄膜电极DSCs在未开灯的状态下，具有较大的反向暗电压。反向暗电压的产生主要归结为：在FTO/ TiO2薄膜界面处存在内建电势Vb所致，而且与DSCs的开路电压方向相反。并且，结合文献报道和DSCs工作原理，从FTO/TiO2薄膜界面内建电势、薄膜与FTO导电面结合牢度以及内建电势与PN结原理相类比三个方面，对厚膜DSCs的实验结果进行了综合的解释。
其他摘要	The Dye-sensitized Nanocrystalline Solar Cells(DSCs) has obtained a great deal of attention and made great progress for a decade years because of its low cost, high energy conversion, simple productive technics, and other advantages. But in fact there are so many relative factors effecting on the capacities of DSCs need to be improved, and the factors can be listed as follows: packing technics, energy conversion, big scales and so on. It is no doubt that the direct and effective method to reduce the cost of DSCs is to increase the DSCs` energy conversion. There are also many factors those restrict the DSCs` energy coversion, including the absorption efficiency of dyes, the transfers of electrons through the TiO2 film, the reactive speed of redox reaction in the electrolyte between I- and I3-, et al. and we mainly research how the transfers of electrons through the TiO2 film effects the energy conversion of DSCs in the paper. At first, TiO2 thin films with Pt distributing in bottom layer or uniformly were prepared by sol-gel method through alternate dip-coating process. The photoelectrochemical behaviors of the films were measured by a three-electrode system, and the dye-sensitized solar cells (DSCs) with these films as anodes were assembled to investigate the photoelectric conversion capacities. The results show that the photocurrent of the TiO2 film with Pt distributing in bottom layer is higher than the pure TiO2 film and more enlarged by ethanol addition into the electrolyte as holes’ capture agent. The above phenomena can be explained based on the separation of photogenerated carriers and photoholes’accumulation in the surface layer. Due to photoholes accumulating in the surface, the excited electrons can transfer to TiO2 thin film more easily. The short-circuit Isc and the open-potential Voc are increased obviously. Secondly, it must be pointed that the photoelectrical signals of above DSCs are very small, because the TiO2 films are so plat and thin that they can not absorb more quantities of dye. For the purpose of increasing the energy conversion of DSCs, we used the TiO2 powders purchased from a semiconductor factory to prepare a kind of thick and porous TiO2 films by the blading method, and we assembled DSCs using the prepared TiO2 thick films. Moreover, we improved the structures of the TiO2 thick films, which we prior to prepared the thin films with a certain layers by dip-coating method between FTO and TiO2 thick films, and the thin films include TiO2 and Pt-TiO2 thin films with a certain layers. The photoelectrical signals are measured by a three-electrode system, and the irradiation intensity of the light source is 41mW/cm2. In contrast to the unimproved TiO2 thick film, the improved TiO2 thick films reduce a small quantity of open-potential，but it increase the short-current more obviously. Surprisingly, we find that there is a reverse dark potential appeared while DSCs being measured in the dark, if the TiO2 thick films contact with FTO directly. Finally, we use the work principles of DSCs, internal potential in the interface of FTO/TiO2 film and PN junction to complain the transfers mechanism of electrons through TiO2 film, and we also complain how the dark potential form and how to reduce or eliminate the dark potential.
页数	67
语种	中文
文献类型	学位论文
条目标识符	http://ir.giec.ac.cn/handle/344007/4013
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	王彦明. 染料敏化TiO2太阳能电池薄膜电极的研制[D]. 广州能源研究所. 中国科学院广州能源研究所,2007.

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