Tracking the coherent generation of polaron pairs in conjugated polymers.
Tracking the coherent generation of polaron pairs in conjugated polymers.
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DOI：
10.1038/ncomms13742
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发表时间：
2016-12-08
影响因子：
16.6
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中科院分区：
文献类型：
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有机半导体的光激发不仅能产生电荷中性的电子-空穴对(激子)，还能产生高产额的电荷分离极化子对。这种电荷分离背后的微观机制已经争论了很多年。在这里，我们使用超快二维电子能谱研究了典型聚合物薄膜中极化子对形成的动力学。我们观察到多周期峰值振荡持续约1 ps，这是室温下振动量子相干性的明显特征。测量的二维谱显示出明显的峰分裂，表明该聚合物的基元光学激发是激子-极化子对的杂化，强烈耦合到主导的欠阻尼振动模式。相干振动耦合导致超快极化子对的形成，加速了电荷分离动力学，使其对无序不敏感。这些发现为定制有机材料中的光到电流转换开辟了新的视角。了解电荷转移动力学对于设计用于光电子应用的高性能有机半导体是至关重要的。在这里，作者证明了激子、极化子对和长寿命振动模在聚噻吩中强耦合到1 皮秒。
The optical excitation of organic semiconductors not only generates charge-neutral electron-hole pairs (excitons), but also charge-separated polaron pairs with high yield. The microscopic mechanisms underlying this charge separation have been debated for many years. Here we use ultrafast two-dimensional electronic spectroscopy to study the dynamics of polaron pair formation in a prototypical polymer thin film on a sub-20-fs time scale. We observe multi-period peak oscillations persisting for up to about 1 ps as distinct signatures of vibronic quantum coherence at room temperature. The measured two-dimensional spectra show pronounced peak splittings revealing that the elementary optical excitations of this polymer are hybridized exciton-polaron-pairs, strongly coupled to a dominant underdamped vibrational mode. Coherent vibronic coupling induces ultrafast polaron pair formation, accelerates the charge separation dynamics and makes it insensitive to disorder. These findings open up new perspectives for tailoring light-to-current conversion in organic materials. Understanding of charge transfer dynamics is essential to the design of high-performance organic semiconductors for optoelectronic applications. Here, the authors show that excitons, polaron pairs and a long-lived vibrational mode are strongly coupled to each other up to 1 picosecond in polythiophene.
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影响因子：
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作者：
Orgiu, E.;George, J.;Ebbesen, T. W.
通讯作者：
Ebbesen, T. W.
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Spano, Frank C.
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Ploog, KH
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通讯作者：
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