Zirzlmeier Johannes, Lavarda Giulia, Gotfredsen Henrik, Papadopoulos Ilias, Chen Lan, Clark Timothy, Tykwinski Rik R, Torres Tomás, Guldi Dirk M
Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-University Erlangen-Nuremberg, Egerlandstraße 3, 91058 Erlangen, Germany.
Nanoscale. 2020 Nov 26;12(45):23061-23068. doi: 10.1039/d0nr06285e.
In contrast to previous work, the synergy between panchromatic absorption and molecular singlet fission (SF) is exploited to optimize solar energy conversion through evaluation of the distance dependence of intramolecular Förster Resonance Energy Transfer (i-FRET) in a series of subphthalocyanines (SubPcs) linked to pentacene dimers (Pnc2s). To provide control over i-FRET, the molecular spacer rather than the energy donating SubPc is tailored in the corresponding SubPc-Pnc2 conjugates in terms of length (i.e., the number of aryl units) and flexibility (i.e., presence or absence of a CH2 group). AM1-CIS calculations support the experiments, which underline the importance of the molecular spacer to impact not only the i-FRET dynamics, but also the dynamics of intramolecular singlet fission (i-SF). For example, an additional phenyl group slows down both i-FRET and i-SF by a factor of ∼3.8 and ∼1.6, respectively, by a quinone-like conjugation pattern that affords a pentacene acceptor orbital that is fairly delocalized over both pentacenes and the bridging phenyl.
与之前的工作不同，本文利用全色吸收与分子单重态裂变（SF）之间的协同作用，通过评估一系列与并五苯二聚体（Pnc2）相连的亚酞菁（SubPc）分子内福斯特共振能量转移（i-FRET）的距离依赖性，来优化太阳能转换。为了控制i-FRET，在相应的SubPc-Pnc2共轭物中，通过调整分子间隔臂（而非能量供体SubPc）的长度（即芳基单元的数量）和灵活性（即是否存在CH2基团）来实现。AM1-CIS计算结果支持了实验，强调了分子间隔臂不仅对i-FRET动力学，而且对分子内单重态裂变（i-SF）动力学都有重要影响。例如，一个额外的苯基会使i-FRET和i-SF分别减慢约3.8倍和约1.6倍，这是通过一种醌类共轭模式实现的，该模式使并五苯受体轨道在两个并五苯和桥连苯基上都有相当程度的离域。
