Cordones Amy A, Pemmaraju C Das, Lee Jae Hyuk, Zegkinoglou Ioannis, Ragoussi Maria-Eleni, Himpsel Franz J, de la Torre Gema, Schoenlein Robert W
Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
J Phys Chem Lett. 2021 Feb 4;12(4):1182-1188. doi: 10.1021/acs.jpclett.0c03725. Epub 2021 Jan 22.
Zinc porphyrin solar cell dyes with donor-π-acceptor architectures combine light absorber (π), electron-donor, and electron-acceptor moieties inside a single molecule with atomic precision. The donor-π-acceptor design promotes the separation of charge carriers following optical excitation. Here, we probe the excited-state electronic structure within such molecules by combining time-resolved X-ray absorption spectroscopy at the N K-edge with first-principles time-dependent density functional theory (TD-DFT) calculations. Customized Zn porphyrins with strong-donor triphenylamine groups or weak-donor tri--butylbenzene groups were synthesized. Energetically well-separated N K-edge absorption features simultaneously probe the excited-state electronic structure from the perspectives of the macrocycle and triphenylamine N atoms. New absorption transitions between the macrocycle N atoms and the excited-state HOMO vacancy are observed, and the triphenylamine associated absorption feature blue-shifts, consistent with partial oxidation of the donor groups in the excited state.
具有供体-π-受体结构的锌卟啉太阳能电池染料在单个分子内以原子精度结合了光吸收体（π）、电子供体和电子受体部分。供体-π-受体设计促进了光激发后电荷载流子的分离。在此，我们通过将N K边的时间分辨X射线吸收光谱与第一性原理含时密度泛函理论（TD-DFT）计算相结合，来探测此类分子内的激发态电子结构。合成了带有强供体三苯胺基团或弱供体三叔丁基苯基团的定制锌卟啉。能量上分离良好的N K边吸收特征从大环和三苯胺N原子的角度同时探测激发态电子结构。观察到了大环N原子与激发态HOMO空位之间新的吸收跃迁，且与三苯胺相关的吸收特征发生蓝移，这与激发态下供体基团的部分氧化一致。
