微囊化卟啉/石墨烯非共价复合染料的可控制备及构效调控

There are some problems existing in the nanocrystalline thin film semiconductor materials prepared by the single porphyrin dye, including self polymerization of porphyrin monomers, weak interfacial adsorption and poor electronic transmission, which result in low photoelectric response efficiency in dye-sensitized solar cell. Contraposing above problems, the project aims to prepare a kind of noncovalent porphyrin-graphene composite microcapsule with adjustable structure and special functionality. The microcapsules will be obtained by embedding porphyrins and graphene. Moreover, the synthesis of microcapsules combines the hyperconjugation structure and multi electron characteristics of porphyrin and the electroconductivity and electron-accepted property of graphene. By synthesizing the porphyrin-graphene dye-sensitized composite microcapsules, the physical and chemical properties and electron transports of porphyrins will be improved effectively and the porphyrin or grapheme monomers will not easily polymerize. Meanwhile, a kind of novel porphyrin supramolecular complex will be obtained using the printing or coating technology, which uniformly and closely transfers the dopped capsule core materials to the nanocrystalline semiconductor thin films. The investigation will not only greatly enhance the light absorption properties of dyes, but also can improve the properties of charge transfer between photosensitizers and nanocrystalline semiconductor materials. The core science problems in the photoelectric conversion of photosensitizers are the relationship between the microcosmic molecular structures of porphyrin-graphene supramolecular complexes and the macroscopic photoelectric conversion performances, which will be emphatically investigated. By analyzing the relationship of structures and performances, the more practical novel photosensitizers with special structures will be predicted, designed and synthesized. Eventually, the above results will provide important fundermental data and theoretical bases for developing an efficient and environmental friendly energy utilization technology.

针对卟啉单分子染料的易于自聚、界面吸附弱及电子传输差等问题，进而导致染料敏化太阳能电池光电响应效率低的问题，本项目旨在利用卟啉的超共轭结构及富电子特性和石墨烯的易于导电及强接受电子能力，将卟啉与石墨烯非共价结合包埋得到一种结构可调控、具有功能性的复合染料微胶囊，从而有效地改善染料的物化性质和电子传输性能，避免卟啉和石墨烯单体因自聚而失活。同时，利用一定压力下囊内芯材的结构及性能易于变化的特点，借助印刷或涂布的方式使卟啉/石墨烯通过分子间作用力结合形成一种超分子结构，紧密地锚固于纳米晶半导体薄膜上，既可增强染料的吸光性能，使其更有效地利用太阳能，又可提高染料与纳米晶半导体之间的电荷传输性能。重点研究复合染料进行光电转换的核心问题，即卟啉-石墨烯超分子的微观结构与宏观的光电转换性能之间的关系，以期预测、设计、制备更实用的光敏染料，最终为开发一种高效、环保的新能源利用技术提供理论依据和实际指导。

当前，影响染料敏化太阳能电池（DSSC）效率的因素主要包括吸附染料的光阳极、电解质和对电极。卟啉染料易自聚、成膜差，液态电解质易挥发、难封装，对电极转化效率低、原料成本高，这些问题限制了DSSC的发展。.针对上述问题，本项目在卟啉染料的设计、准固态电解质的制备、对电极的构建、功能微胶囊的应用等方面进行了深入的研究，为DSSC的发展提供了相关依据。. 项目主要结果如下： .（1）采用理论与实验的方法对卟啉合成过程的过渡态和中间体进行研究，验证了羧酸的催化作用和硝基苯的氧化作用；以锌卟啉为基准染料，在电子供体上引入不同供电性的五元杂环，利用密度泛函的方法预测并设计得到新型的卟啉染料敏化剂。.（2）通过丝网印刷工艺制备DSSC光阳极薄膜，包含4层光吸收层与1层散射层，利用TiCl4处理光阳极提高了DSSC的开路电压和短路电流，使用小粒径TiO2作为光吸收层促进了DSSC对光辐射的利用，封装得到光阳极面积为1cm2的太阳能电池，转换效率5.4%。.（3） 利用材料复合技术得到了高孔隙率、高比表面积的SiO2气凝胶，在3秒内即可凝胶化得到准固态电解质，通过丝网印刷实现电解质的转移，以SiO2气凝胶@石墨烯为凝胶剂的准固态DSSC转换效率最高可达8.25%；封装得到小面积DSSC（0.16cm2），短路电流密度14.57mA•cm-2，光电转换效率6.57 %。.（4）通过原位聚合的方法得到以蜜胺树脂为壳层和以导电溶液为芯材的自修复微胶囊，粒径10-20µm，可承受14N的压力，具有良好的相变潜热和热力学性能，将其用于电池电极或导电线路中，通过对断路部位的微胶囊施加一定压力，即可使其释放芯材导通电路，电导率为6.232ms/cm。.（5）利用电化学循环伏安法在导电基底制备得到聚苯胺薄膜，将其作为对电极具有表面均匀、不易脱落、薄膜厚度可调控且无需高温处理的特点，聚苯胺作对电极的DSSC开路电压0.74V，短路电流15.34mA cm-2，填充因子0.64，转化效率7.27%，高于Pt作对电极的7.23%。.综上，本项目对卟啉合成、器件结构、微胶囊性能等进行了系统的研究，上述结果将对新能源材料的发展起到积极的促进作用。