Unraveling Direct and Indirect Energy Transfer Pathways in a Light-Harvesting Dendrimer
Unraveling Direct and Indirect Energy Transfer Pathways in a Light-Harvesting Dendrimer
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DOI：
10.1021/acs.jpcc.0c06539
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发表时间：
2020-10-15
影响因子：
3.7
通讯作者：
Galindo, Johan F.
中科院分区：
文献类型：
--
作者：
Camila Aguilera, Maria;Roitberg, Adrian E.;Galindo, Johan F.
捕光和分子内能量传递是自然界光合作用的基本过程。通过研究能够模仿自然系统的人工集光天线，可以全面了解调节此类过程效率的主要结构、动态和光学特性。树枝状聚合物是最受关注的人工捕光分子之一。然而，它们必须是明确的和高度分支的共轭结构，产生分子内能量梯度，保证有效和单向的能量转移。在这里，我们探索的贡献，负责在一个大的，复杂的聚（亚苯基-乙炔基）树枝状聚合物，其架构是特别设计的，以进行最初吸收的光子朝向一个空间局部化的能量汇远离其表面，避免其淬火环境中的高效能量funeries的不同机制。为此，我们用非绝热激发态分子动力学方法模拟了非辐射光致能量弛豫和再分布。以这种方式，两种可能的直接和间接的途径激子迁移，以前报道的时间分辨光谱，被定义。我们的研究结果刺激了未来的发展，新的合成树枝状聚合物的应用在分子为基础的光子器件中，其中的光电发射效率的增强可以通过不同的分子内能量转移途径之间的详细平衡的变化来预测。
Light-harvesting and intramolecular energy funneling are fundamental processes in natural photosynthesis. A comprehensive knowledge of the main structural, dynamic, and optical properties that regulate the efficiency of such processes can be deciphered through the study of artificial light-harvesting antennas, capable of mimicking natural systems. Dendrimers are some of the most explored artificial light-harvesting molecules. However, they have to be well-defined and highly branched conjugated structures, creating intramolecular energy gradients that guarantee efficient and unidirectional energy transfer. Herein, we explore the contributions of the different mechanisms responsible for the highly efficient energy funneling in a large, complex poly(phenylene-ethynylene) dendrimer, whose architecture was particularly designed to conduct the initially absorbed photons toward a spatially localized energy sink away from its surface, avoiding its quenching by the environment. For this purpose, the nonradiative photoinduced energy relaxation and redistribution are simulated by using nonadiabatic excited state molecular dynamics. In this way, the two possible direct and indirect pathways for exciton migrations, previously reported by time-resolved spectroscopy, are defined. Our results stimulate future developments of new synthetic dendrimers for applications in molecular-based photonic devices in which an enhancement in the photoemission efficiency can be predicted by changes in the detailed balance between the different intramolecular energy transfer pathways.