染料敏化太阳能电池中PEG基体聚合物电解质和低铂负载量对电极研究

【作者】 李品将；

【导师】 吴季怀；

【作者基本信息】 华侨大学 ， 材料学， 2008， 博士

【摘要】 染料敏化太阳能电池(DSSC),具有低成本、易制备和高的光电转换效率等优点,成为当前光电转换材料和纳米技术研究领域中的热点之一。染料敏化太阳能电池的研究不仅对探索制备廉价太阳能电池的途径有实际意义,其研究对半导体光电子学、纳米多孔材料、有机电解质、材料界面理论及光电化学等方面均具有重要的科学意义。本论文较为详细地综述了染料敏化太阳能电池的国内外研究进展,针对DSSC中电解质和对电极研究开发中存在的问题,开展了PEG基体聚合物电解质和低铂对电极的研究。通过对制备不同聚合物电解质基体的研究,探讨聚合物电解质离子导电的一般规律,考察聚合物电解质中不同的组成成分对电解质离子电导率以及聚合物准固态DSSC光电性能的影响,以期提高聚合物染料敏化太阳能电池的使用寿命和光电性能;制备了低铂含量的铂对电极和铂/碳黑复合对电极,研究其对DSSC光电性能的影响,以期获得高活性、制备成本更为低廉的对电极。主要研究内容如下:1.采用共混的方法制备了PEG/PVP聚合物电解质,对其组成进行了优化;通过对无机碘盐筛选,在该电解质体系中采用KI具有较高的离子导电性能;考察了KI浓度与聚合物电解质电导率的变化关系,用离子对模型对这一变化规律进行了解释;对聚合物电解质电导率?温度特性关系分析,电解质的电导率随着温度的升高而增加,其σ-T曲线符合Arrhenius方程;表征了碘及碘化钾在共混聚合物基体中的溶解特性,并用聚合物电解质组装了DSSC,测定了光电性能,讨论了PVP对其光电性能影响,在优化的条件下,获得了4.01%的光电转换效率;考察了共混聚合物电解质DSSC长期稳定性,表现出了优于液体电解质的长期稳定性,在两个月的测试时间内,总光电转换效率的变化在±5%以内。2.通过缩合反应制备了PEG-TEOS交联凝胶聚合物电解质。用FTIR和DSC对交联聚合物进行了表征,分析了以PEG与TEOS的交联反应,将液态的PEG-1000凝胶化。优化了I?/I3?氧化还原电对在PEG-TEOS交联凝胶聚合物基体中的浓度,获得了该电解质体系中离子电导率最大值为3.12毫西门子/厘米;采用拉曼光谱表征,证实了在聚合物电解质中I3?和I2n+3?(n = 1, 2, 3,…)的形成以及单质碘的溶解;在最优化电解质的条件下(交联聚合物电解质中含有KI 0.60摩尔/升和I2 0.06摩尔/升),该染料敏化太阳能电池在100毫瓦/平方厘米的光强下获得了4.97%的光电转换效率,也表现出了良好的稳定性。3.采用铂纳米粒子电沉积法制备了用于染料敏化太阳能电池的低铂含量的对电极,表征了铂纳米粒子的还原生成及其形貌;考察了该制备方法电沉积时间与其组装的DSSC的光电转换效率的关系,发现当FTO导电玻璃在铂纳米水溶胶中电沉积时间达到20分钟时,可以获得较好的光电效果并且对电极铂的含量相对较少。并与电化学电镀法、热分解法制备的铂对电极进行了比较,以铂纳米粒子电沉积法制备对电极的DSSC获得的光电性能与电化学电镀法制备的对电极相当,并高于热分解法制备的对电极。4.用NaBH4还原法将铂负载于碳黑之中,制备了用于DSSC的铂/碳黑复合对电极,表征了铂纳米粒子在碳黑上的负载及其形貌;并用循环伏安法比较了电化学电镀法制备的铂电极、碳黑电极及铂/碳黑复合电极在I?/I3?体系中的的催化活性;考察了铂/碳黑复合对电极中铂的负载量对DSSC光电性能的影响;通过光电性能的比较,发现采用铂/碳黑复合对电极的DSSC具有不低于采用铂金对电极的DSSC相当的光电性能,它们的光电转换效率分别为6.72%和6.63%。通过上述研究,以期对DSSC中电解质和对电极的进一步研究提供参考,并为DSSC的实际应用提供一些技术和工艺参数。更多还原

【Abstract】 Dye-sensitized solar cells (DSSC) have been one of hot-spots in the field of materials for photoelectric conversion and nanotechnology because of its low-cost, easy-made and high-efficiency. It makes sense in research dye-sensitized solar cells not only in the aspect of groping the manufacture way for low cost and high performance solar cells but also in the aspect of its scientific values in the fields such as semiconductor photoelctronics, nanometer porous material, organic electrolytes and photo-electric chemistry. In this paper, the research progress of DSSC in domestic and overseas was reviewed. In order to solving present problems of the electrolyte and the electrode in DSSC, the polymer electrolyte of PEG matrix and the counter electrode with low platinum loading were studied. In this dissertation, different kinds of polymer matrix electrolytes were researched in order to improve the overall solar energy conversion efficiency and long-term stability of the DSSC. The transmission mechanism of the ionic conductivity in the polymer electrolyte and the affects of various compositions of the polymer electrolyte on the performances of DSSC were discussed. The counter electrodes of low platinum loading were also prepared and researched in order to obtaining the counter electrodes with high activity and low cost for application in DSSC. There are some major works in the following:1. Polyblend electrolytes consisting of KI and I2 dissolved in a blending polymer of polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG) were prepared and applied to DSSC. And the effects of polyblend electrolytes were investigated to improve the photovoltaic performance of DSSC. The influence of KI concentration on ionic conductivity of the polymer electrolyte was studied. Its result has also been proved by estimation using the ion pair model. By study different inorganic salts, it is concluded that the high solubility and good performance can be attained when potassium iodide was used. By study the character of conductivity-temperature for polymer electrolyte, it was found that followed the Arrhenius principle. The formation of I3? in polymer electrolytes had been characterized by XPS. The effects of polyblend polymer electrolytes on the DSSC were also evaluated. The light-to-electricity conversion efficiency of the DSSC assembled with optimized electrolyte composition was calculated to be 4.01%. The polyblend electrolyte showed the more stable than the liquid electrolyte, the total efficiency changes in the range of±5% for two month.2. The cross-linked PEG-1000 was prepared by condensation reaction with tetraethoxysilane (TEOS). With the cross-linked PEG-1000 as polymer host, the highest ionic conductivity of the polymer electrolyte was achieved 3.12 mS·cm-1. FT-Raman spectra were obtained to confirm the formation of I3? and polyiodides (I2n+3?, here n = 1, 2, 3,…) and complete dissolution of iodine in the polymer electrolyte. Based on the optimized cross-linked PEG electrolyte, the best result of the quasi-solid state dye-sensitized solar cell (QS-DSSC) was the light-to-electricity conversion efficiency of 4.97%. The polymer electrolyte also showed the good stable for application in DSSC.3. Platinum nanoparticles were electrodeposited on FTO conducting glass substrate as counter electrode for application in dye-sensitized solar cells (DSSC). Images of TEM and SEM showed that platinum nanoparticles were with the mean size of 20-30 nm and homogeneously distributed on the surface of the FTO conductive glass sheet. Using such a counter electrode, DSSC showed 6.40% overall energy conversion efficiency under one sun illumination. It exhibited the same high-performance as the DSSC with a platinum counter electrode prepared by electroplating. Furthermore, the present preparation method for the platinum counter electrode has the advantage of low platinum loading.4. Pt/Carbon black counter electrode was prepared for application in DSSC. The image of TEM and XRD pattern showed that platinum was successfully supported and homogeneously dispersed on the carbon black powder. The cyclic voltammetry reveals that the Pt/Carbon black electrode showed high electrocatalytic activity in iodide/triiodide redox reaction. Using such a counter electrode with low platinum loading (1.5 wt% platinum loading on carbon black), DSSC achieved 6.72% overall energy conversion efficiency under one sun illumination. It exhibited the same high-performance as the DSSC with a platinized counter electrode.Based on above result of the research, we hope that the reference could be offer for further study in DSSC and the techniques and technological parameters could be provided for practical application of DSSC.更多还原