【作者】 纪伟伟；

【导师】 赵颖； 张晓丹；

【作者基本信息】 南开大学 ， 微电子与固体电子学， 2010， 硕士

【摘要】 近年来,染料敏化太阳电池(DSC)因原材料价格低廉,工艺简单,转换效率较高,应用前景广泛,被认为是具有高性价比的新一代太阳电池,而引起世界各国的广泛关注。在提高染料敏化太阳电池光电转换效率的同时,进一步降低电池的制造成本,是本领域当前国际研究的热点。本论文针对染料敏化太阳电池的光阳极和对电极制造过程中出现的问题,提出了新型成膜剂—聚乙烯吡咯烷酮(PVP)制备高致密性TiO2薄膜,采用新结构构建对电极,拟在降低材料成本、提高薄膜成品率的同时,进一步提高玻璃基底染料敏化太阳电池的转换效率。本论文的主要研究工作如下：1.高致密性TiO2薄膜的研究本文采用刮涂和高温烧结相结合的方法在玻璃基底上制备纳米TiO2薄膜。在TiO2浆料的制备中,针对常规纳米Ti02薄膜易出现裂纹等缺陷的问题,提出采用新型成膜剂—PVP制备纳米TiO2薄膜。首先进行了不同PVP系列对Ti02薄膜特性及其电池性能影响的研究,优选出K30系列PVP成膜剂；然后针对优选出的K30系列PVP与常用粘结剂—乙基纤维素(M70)进行对比实验,探寻最优成膜剂。以期在宏观上减少Ti02薄膜的裂缝,从而降低染料敏化电池的暗电流;在微观上增加TiO2薄膜孔隙率,从而增加单层染料分子的吸附量,提高光生电子数,增加短路电流,使电池效率进一步提高。为增加光在TiO2薄膜中的散射,开展了400nm大颗粒层和不同尺寸的Ti02颗粒对TiO2薄膜性能及电池性能影响的研究。2.对电极结构的研究对电极在染料敏化太阳电池中是不可或缺的一部分。目前多采用镀铂的对电极,即采用不同方法将铂镀在导电玻璃上。本论文尝试引入高反射率、高电导率的金属铝、银,与具有高催化特性的铂结合,形成新型对电极结构,以期改善染料敏化电池的光利用率,进一步提高电池效率。在保持铂催化功能的前提下,尽可能减薄铂膜的厚度,降低电池成本。但对电极的导电和光反射特性将降低。为此,提出两种新型对电极结构。第一种由基底材料、铝薄膜和其上的铂薄膜构成。此新型对电极具有如下优点：1)基底材料的选择更自由,可以是普通玻璃、塑料、不锈钢等；2)铝的电导率高,可显著降低电池串联电阻,改善欧姆接触；3)铝的价格便宜；4)铝膜制备工艺简单、沉积温度低、沉积速率高；5)铝薄膜对可见光具有高反射率,可增加光程,提高太阳光利用率。在对新型对电极特性及其对电池性能影响的初步研究后,发现金属铝等不耐电解液的腐蚀问题。为此,本论文提出了系列改进措施。针对热分解法制备的铂层较薄、呈透明的特点,提出第二种新型对电极结构。其由铂、基底材料和高反射性的金属(铝、银)构成。该结构可将未被染料分子充分吸收而透过透明铂薄膜的部分太阳光,由金属铝或银薄膜将之反射回染料敏化电池中,从而提高太阳光的利用率,改善电池特性。而且,该结构也解决了上述第一种新型对电极结构中金属铝等不耐电解液腐蚀的问题。本论文针对第二种新型对电极,进行了其对电池性能影响的初步研究。3.以FTO导电玻璃为衬底、用PVP做成膜剂制备的染料敏化太阳电池的光电转换效率为6.37%。将提出的第一种新型对电极用于DSC中,电池效率由3.46%提高到7.07%,同样,背面蒸发金属银制备的第二种新型对电极组成DSC的效率增幅最大,由4.39%提高到6.05%。更多还原

【Abstract】 Due to the low cost, easy to fabricate, highly photovoltaic conversion efficiency, and wide applications prospects, Dye sensitized solar cells (DSC) have been intensively studied all over the world during the last decade. It is an international research focus that the DSC’ efficiency is improved and the production cost is reduced at the same time. In this paper, we considered a question appearing in the process of photo anode and counter electrode and proposed a new type of filmogen-Poly vinyl pyrrolidone(PVP). Highly compact TiO2 thin films were prepared with a new type filmogen, Poly vinyl pyrrolidone(PVP). It was found that new type of counter electrode can improve the conversion effiency of glass subtrate DSC. Main researches in my paper are as follows:1. Researches on highly compact TiO2 thin filmsIn this paper, TiO2 thin films were prepared on conductive glass with methods of doctor blade and high temperature sintering. In the preparation process of TiO2 pastes, a new kind of filmogen (PVP) was proposed directing at solving the crash of TiO2 thin films. First, different series of PVPs influenced the quality of TiO2 thin films and solar cells’ performances, which aimed to seek the best series filmgen, that is to say, K30 series PVP. Second, TiO2 thin films were prepared by different filmogens such as M70 or K30 PVP, which were compared in order to seek the optimum filmogen, that is to say, looking for TiO2 thin films that can reduce cracks from view of macroscopy. In view of microscopy, increasing the absorption of single layer dyes, enhancing the number of photo-electronics and improve short circuit and solar cell’ efficiency. In order to increase light scattering in TiO2 thin films, we analyzed how 400nm large particles layer and different size TiO2 particles influenced quality of TiO2 thin films and performances of solar cells.2. Researches on improving counter electrodeCounter electrode was a part of vital importance in DSC. Now the platinum counter electrode on conductive glass is often prepared by different preparation methods. In this paper, high reflective and conductive metal, such as aluminum or silver were drawn into counter electrode, which composed new types counter electrode, in order to raise light use ratio and solar cells’ efficiency.In the premise of keeping the platinum catalysis, the thickness of platinum was reduced, however, the reflectance and conduction of counter electrode was also reduced. For this reason, two types of counter electrodes were proposed. First, a new type of counter electrode consisting of glass substrate, aluminum film and platinum film was proposed. The advantages of this kind of counter electrode are as follows:1) Substrate materials can be selected in a wide range, such as general glass, plastic and stainless steel.2) The high conductivity of aluminum can significantly reduce series resistance of DSC and improve ohmic contact.3) The cost of aluminum is much cheaper.4) The deposition of aluminum film is a process, which is very easy, low temperature, high deposition rate.5) Aluminum has high reflectance to visible light, which can make incident light reflect on the TiO2 layer again and improve the utilization of sunlight. But due to the strong causticity of electrolytes, some measures are proposed.According to the characteristic of thin and transparent platinum by a method of thermal decomposition, a new structure of counter electrode, which was formed by platinum thin film, FTO, glass, and silver thin film or silver nanoparticles, was proposed. This new structure that coated with a layer of silver or aluminum on the back side of conductive glass, can obviously make more use of sunlight and increase the short-circuit current. It was evident that this new structure of counter electrode only utilized the reflectance of silver and had no effect on improving conductance of the counter electrode. The second type of counter electrode resolves the strong causticity of electrolytes about the first counter electrode. For the second new type of counter electrode, its influence on solar cell’ performances were researched. 3. Final, the efficiency of DSC based on conductive FTO glass was 6.37%. The first new type of counter electrode was proposed, which applied for DSC and improved solar cells’efficiency from 3.46% to 7.07%. And then the second new type of counter electrode that metal silver was evaporated onto back of conductive glss, was proposed to use in DSC and increase DSC’ efficiency from 4.39% to 6.05%.更多还原