氮反转类卟啉光吸收特性、激发态动力学及分子结构调控

Porphyrin compounds have wide applications due to their broad absorption spectrum, ease of fabrication, lower cost and environment-friendly characteristic. Currently one of the attractive research interests is broadening absorption spectra of porphyrin compounds to improve photoelectric conversion of porphyrin-sensitized solar cell (PSSC). The molecule structure of N-confuse is a promising method to improve photoelectric conversion. However, the excited state dynamics and the relaxation mechanism are still not clear. Moreover, how to design molecule structure for improving photoelectric conversion still need more research work. Hence in this project, our research is mainly focused on two aspects by combining Z-scan, pump-probe，time-resolved transient absorption techniques and Density Functional (DFT) methods: (1) The influence of molecular structures of NCTPP compounds on their photon absorption characteristic and excited-state dynamic is investigated and the related physical and chemical mechanism is revealed; (2) Based on previous experimental and theoretical study novel molecular structure of NCTPP compounds for improving photoelectric conversion are pertinently designed. The proposed research is expected to provide a basic guide for investigation of structure-property relation of porphyrin compounds and promote the application of NCTPP compounds in solar cell field.

卟啉化合物具有光谱响应范围较宽、制备简单、成本低、环境友好等一系列优点，应用前景广阔。目前拓宽卟啉化合物吸收光谱，进而提高卟啉敏化太阳能电池光电转换率是卟啉化合物研究的热点之一。氮反转是一种通过改变母体结构对称性提高光电转换性能的新途径，但氮反转类卟啉(NCTPP)的激发态动力学和弛豫机制尚不清楚，另外如何调控分子结构提高其光电转换效率仍需研究。因此本项目以NCTPP衍生物为研究对象，综合利用Z-scan、泵浦探测和时间分辨瞬态吸收光谱等技术，结合密度泛函理论计算展开两方面研究：（1）揭示结构设计对NCTPP光吸收特性及激发态动力学的影响规律，深入分析其内在物理化学机理；（2）结合理论研究有针对性地设计新型NCTPP衍生物分子，全面提高NCTPP类化合物的光电转换率。希望本项目的实施能够为揭示卟啉化合物的物构关系提供科学依据，推进NCTPP化合物在卟啉染料太阳能电池领域的应用。

拓宽卟啉化合物吸收光谱，有望提高卟啉敏化太阳能电池的光电转换率，以四苯基卟啉为母体的氮反转卟啉（NCTPP）及其化合物为提高光电转换率提供了新的选择。本项目主要研究了NCTPP化合物光吸收特性、激发态动力学及其物构关系。已完成的主要工作有（1）研究了若干NCTPP金属衍生物的内转换速率，S1态寿命及系间跃迁时间之间的差异，并从原子电子态角度给出解释。中心取代金属原子d电子组态中电子数目越少，就越有利于激发态下电子从卟啉转移到金属原子的d电子组态中，进而具有更快的电荷转移速度。（2）研究了两种典型外围取代对卟啉光吸收特性及激发态动力学的影响规律。研究表明给电子基团可以加速卟啉的激发态内转换速率，使其S1态寿命明显缩短。本研究加深了对卟啉结构－性质关系的理解，对卟啉敏化燃料电池和相关研究起到了很好的促进作用。