D-A-D大共轭π桥结构有机染料的合成及其在太阳能电池中的应用研究

Sensitizer, as one of the key components in the DSSCs, plays a critical function in light harvesting and electron injection. That is to say, the ability of sensitizer directly determines the quality of the DSSCs. The insufficiency light-harvesting capacity, low power conversion efficiency and lack of stability of sensitizers directly influence the development of DSSCs. In our earlier work, we have found that the incorporation of large planar conjugation π bridge into the organic dyes can effectively improve the power conversion efficiencies of dyes. This project focuses on design and synthesis of a series of novel metal-free organic dyes which contain a Donor-Acceptor-Donor (D-A-D) conjugation π-bridge to improve the dyes’ light-harvesting ability and power conversion efficiency. The introducing of the large D-A-D conjugation π-bridge can not only increase the molar extinction coefficient, but also extend the absorption spectra. In addition, the incorporation of the large D-A-D conjugation π-bridge can facilitate the electron transfer from the donor to the acceptor. By testing the photo-physical, electrochemical and photovoltaic performance, the dual relationship between the molecular structure of the dyes and the performance of the cell will be studied and discussed in detail. This design of large D-A-D conjugation structure-based dyes might open up the promising possibility to prepare novel organic dye for an enhanced light-current conversion and provide new ideas to improve photoelectric conversion efficiency and stability of the cells.

光敏染料在染料敏化太阳电池（DSSCs）中扮演着核心作用，它起到吸收太阳光和注入电子的作用，其好坏直接决定了电池的优劣性。光敏染料的捕光能力不足、光电转换效率不高和稳定性不足影响了DSSCs的应用发展。在前期的工作基础中我们发现在有机染料中大共轭平面结构π桥的引入对于提高染料的光电转换效率有较好的效果。本项目拟设计合成一系列基于新型供体-受体-供体(D-A-D)大共轭π桥结构的纯有机染料以提高染料的捕光能力和光电转换效率。D-A-D大共轭π桥的引入不仅能提高染料的摩尔消光系数，又能拓宽染料的吸光范围，还有利于促进分子内电子转移。本项目的开展旨在通过对染料光物理、电化学和光伏性能的系统研究来理解这一类新型的染料结构与性能之间的关系，揭示这一体系染料的内在规律。为设计合成新型高效有机敏化染料、提高染料敏化太阳电池的光电转换效率、增加电池的稳定性提供新思路和理论依据。

染料敏化太阳电池是一类非常有潜力的能将太阳能转化为电能的光电转换装置。光敏染料在电池中扮演着至关重要的作用，它的好坏直接决定了电池性能的优劣。本项目针对有机光敏染料捕光能力不足和光电转换效率不高等问题设计合成了一系列基于D-A-D大共轭平面π桥结构的纯有机染料，表征了其分子结构，研究了该系列染料的光物理、电化学和光伏性能，探讨了该系列染料的分子结构与电池性能之间的构效关系。本研究项目取得了一些重要的研究结果：1、电子给体和和电子受体的改变能有效调控染料的捕光能力、HOMO和LUMO能级、电池的光伏性能；2、具有大空间位阻结构基团的引入能够有效抑制染料在二氧化钛表面的聚集和电子复合现象从而提高电池的短路电流和开路电压；3、大共轭平面基团用于双锚固结构染料获得了比单锚固染料更高的摩尔消光系数，更宽的吸光范围和更高的光电转换效率；4、含大共轭平面结构的D-A-π-A型染料中，拉电子能力适中的额外受体的引入更有利于获得高光电转换效率的染料，拉电子能力太强的额外受体容易在分子中形成电子陷阱影响分子内电荷转移。项目发表了9篇SCI论文，2项授权发明专利。项目取得的研究成果为设计合成高效的有机染料提供了一定的理论指导和经验借鉴。