高效吩噻嗪类敏化染料的立体化调控、结构改进及光伏性能研究

Sensitizer is the core component of dye-sensitized solar cells (DSSCs), which directly determines the spectral response range and electron transfer properties，so the development of efficient sensitizer is one of the most effective way to improve the power conversion efficiency. The metal-free organic dyes have developed rapidly in recent years, but there are still problems like interfacial electron recombination, dye aggregation, and spectral response deficiency. This project intends to synthesize novel phenothiazine dyes through three-dimensional modification and structural improvement, and we expect to suppress dye aggregation, reduce electron recombination from the spatial structure, enhance the electron donating ability of donor, finally improve the light-harvesting ability and the overall performance of DSSCs. The core idea is to design the new type of three-dimensional spiral electron donors, coupling with the optimization of auxiliary acceptors, π-bridges, and anchors, as well as the construction of double D-A-π-A branched structures, thereby improving the open-circuit photovoltage (Voc) and short-circuit current density (Jsc). We hope to combine the theoretical calculation to optimize the dyes, to summarize the structure-activity relationship, and to seek the best balance between the spectral response and the internal charge transfer dynamics, so as to providing theoretical and experimental basis for the development of high-performance sensitizers.

敏化剂是染料敏化太阳能电池的核心部件，直接决定了器件的光谱响应范围和电子转移性能，所以开发高效的敏化剂是提高电池效率最为有效的途径之一。纯有机染料近年来发展迅速，但还普遍存在界面电子复合、染料聚集和光谱响应不足等问题。本项目拟通过立体化调控和结构改进等策略，设计、合成结构新颖的吩噻嗪类染料，抑制染料聚集和减少电子复合，增强供体的给电子功能，提高电池的光子捕获能力和整体性能。核心思路是以设计新型立体化螺型供体端为基础，再结合优化辅助电子受体、改进π-桥和锚固基团、以及构建双D-A-π-A分支型等新型结构的方法切实提高电池的开路电压和短路电流。结合理论计算优化染料结构，总结构效关系，寻求光谱响应与电子转移动力学之间的最佳平衡关系，为高性能敏化染料的开发提供理论和实验依据。

敏化剂是染料敏化太阳能电池的核心部件，直接决定了器件的光谱响应范围和电子转移性能，开发高效的敏化剂是提高电池效率最为有效的途径之一。染料光谱响应不足以及电子复合与染料聚集是目前面临的重要科学问题。本项目从分子结构设计入手，围绕吩噻嗪类染料进行立体化调控从空间上阻止电子复合和抑制染料聚集，同时通过共敏化策略和构建超分子染料有效地拓宽器件的光谱响应范围。对N719进行结构改进，设计性能优异的吩噻嗪类供电子部分并通过钌进行配位制备性能优异的染料JR2，其转换效率达到了9.12%，超出了N719约14%（8.03%）。开发了水稳定性的酰肼锚固基团，同时对常用的羧基、氰基丙烯酸和吡啶等锚固基团的性能进行了系统的分析比较。进一步发展了共敏化方法，对共敏化的条件进行了细致筛选，有机小分子S3和S4作为共敏化剂和卟啉染料JA3进行协同作用，光谱吸收在500-600nm区域有了明显的改进，电池转换效率达到了8.20%，提高了32%。设计X型的共敏化剂，使得卟啉染料的转换效率从6.40%增加到了8.08%。针对染料分子的单层结构限制DSSCs发展的这一关键性问题，制备了一种三苯胺类小分子JH1和两个天线卟啉发色团P1和P2，通过超分子自组装的方法进行了电池器件组装，这种自组装策略将其转换效率提高了78%。将几类吩噻嗪天线分子与锚固基团通过金属锌进行自组装，得到的染料A2-Zn-S1器件的转换效率可达4.25%，有效证明了超分子染料的应用可行性。相关成果发表SCI论文12篇，授权发明专利4项，培养硕士研究生2名。本项目将刚性蝶形结构的吩噻嗪作为电子供体引入钌类、锌卟啉类和纯有机类染料分子结构之中并取得了良好的效果，通过自组装的方法制备超分子叠层染料，突破目前单层染料的限制，避免了传统染料复杂的合成步骤与收率较低的严重缺点，对于新型染料的开发具有很好的理论指导意义。