Spectroscopy of Soft Matter, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104 Freiburg, Germany.
Nanoscale Horiz. 2021 Nov 22;6(12):998-1005. doi: 10.1039/d1nh00514f.
Directed transport of singlet excitation energy is a key process in natural light-harvesting systems and a desired feature in assemblies of functional organic molecules for organic electronics and nanotechnology applications. However, progress in this direction is hampered by the lack of concepts and model systems. Here we demonstrate an all-optical approach to manipulate singlet exciton transport pathways within supramolecular nanostructures singlet-triplet annihilation, , to enforce an effective motion of singlet excitons along a predefined direction. For this proof-of-concept, we locally photo-generate a long-lived triplet exciton population and subsequently a singlet exciton population on single bundles of H-type supramolecular nanofibres using two temporally and spatially separated laser pulses. The local triplet exciton population operates as a gate for the singlet exciton transport since singlet-triplet annihilation hinders singlet exciton motion across the triplet population. We visualize this manipulation of singlet exciton transport the fluorescence signal from the singlet excitons, using a detection-beam scanning approach combined with time-correlated single-photon counting. Our reversible, all-optical manipulation of singlet exciton transport can pave the way to realising new design principles for functional photonic nanodevices.
单线态激子定向输运是天然光捕获系统中的关键过程，也是有机电子学和纳米技术应用中功能性有机分子组装的理想特征。然而，由于缺乏概念和模型体系，这方面的进展受到了阻碍。在这里，我们展示了一种全光学方法来操纵超分子纳米结构内单线态激子输运途径——单线态-三重态湮灭，以沿着预定方向强制有效运动的单线态激子。为此，我们使用两个时间和空间上分离的激光脉冲在 H 型超分子纳米纤维的单束上局部光生成长寿命的三重态激子和随后的单线态激子。局部三重态激子作为单线态激子输运的门，因为单线态-三重态湮灭会阻碍单线态激子穿过三重态激子的运动。我们使用检测光束扫描方法结合时间相关单光子计数来可视化这种对单线态激子输运的操纵——即来自单线态激子的荧光信号。我们的这种可逆的、全光学的单线态激子输运操纵为实现功能性光子纳米器件的新设计原则铺平了道路。
