Synthesis and Exciton Dynamics of Triplet Sensitized Conjugated Polymers
Synthesis and Exciton Dynamics of Triplet Sensitized Conjugated Polymers
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DOI：
10.1021/jacs.5b06223
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发表时间：
2015-08-19
影响因子：
15
通讯作者：
Bronstein, Hugo
中科院分区：
文献类型：
--
作者：
Andemach, Rolf;Utzat, Hendrik;Bronstein, Hugo
我们报道了一种新型的多噻吩基主客体共聚物的合成，该共聚物将pt -卟啉络合物（TTP-Pt）纳入骨架，用于有效的单线态到三重态聚合物激子敏化。我们利用瞬态吸收光谱（TAS）在多时间尺度上阐明了该材料薄膜中的激子动力学，并研究了三重态激子形成的机理。在敏化过程中，单线态激子扩散之后，激子从聚合物主链转移到络合物，在那里它经历了系统间交叉到络合物的三重态。我们直接监测了三重态激子从pt -卟啉到聚合物的反向转移，发现60%的复杂三重态激子以1087 ps的时间常数转移。我们提出了聚合物和卟啉三重态之间的平衡，这是由于聚合物主链中的三重态扩散长度较低，因此增加了局部三重态数量，导致三重态湮灭增加。该新系统对三重态敏化太阳能电池和上转换层新材料的设计具有重要意义。
We report the synthesis of a novel polythiophene-based host guest copolymer incorporating a Pt-porphyrin complex (TTP-Pt) into the backbone for efficient singlet to triplet polymer exciton sensitization. We elucidated the exciton dynamics in thin films of the material by means of Transient Absorption Spectrosopcy (TAS) on multiple time scales and investigated the mechanism of triplet exciton formation. During sensitization, singlet exciton diffusion is followed by exciton transfer from the polymer backbone to the complex where it undergoes intersystem crossing to the triplet state of the complex. We directly monitored the triplet exciton back transfer from the Pt-porphyrin to the polymer and found that 60% of the complex triplet excitons were transferred with a time constant of 1087 ps. We propose an equilibrium between polymer and porphyrin triplet states as a result of the low triplet diffusion length in the polymer backbone and hence an increased local triplet population resulting in increased triplet triplet annihilation. This novel system has significant implications for the design of novel materials for triplet sensitized solar cells and upconversion layers.