Tracking the coherent generation of polaron pairs in conjugated polymers.,Nature Communications

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Tracking the coherent generation of polaron pairs in conjugated polymers.
Nature Communications ( IF 14.7 ) Pub Date : 2016-12-08 , DOI: 10.1038/ncomms13742
Antonietta De Sio _{1,

2} , Filippo Troiani ₃ , Margherita Maiuri ₄ , Julien Réhault ₄ , Ephraim Sommer _{1,

2} , James Lim ₅ , Susana F Huelga ₅ , Martin B Plenio ₅ , Carlo Andrea Rozzi ₃ , Giulio Cerullo ₄ , Elisa Molinari _{3,

6} , Christoph Lienau _{1,

2,

7}

Affiliation

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.

中文翻译：

跟踪共轭聚合物中极化子对的相干生成。

有机半导体的光激发不仅产生电荷中性的电子-空穴对（激子），而且产生高产率的电荷分离极化子对。这种电荷分离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光谱来研究在低于 20-fs 的时间尺度上原型聚合物薄膜中极化子对形成的动力学。我们观察到持续高达约 1 ps 的多周期峰值振荡作为室温下振动量子相干性的不同特征。测量的二维光谱显示出明显的峰分裂，表明该聚合物的基本光学激发是杂化的激子-极化子对，与主要的欠阻尼振动模式强烈耦合。相干振动耦合诱导超快极化子对形成，加速电荷分离动力学并使其对无序不敏感。这些发现为定制有机材料中的光电流转换开辟了新的视角。

更新日期：2016-12-09

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