Ultrafast photo-driven charge transfer exciton dynamics in mixed-stack pyrene-perylenediimide single co-crystals
Ultrafast photo-driven charge transfer exciton dynamics in mixed-stack pyrene-perylenediimide single co-crystals
复制标题
混合堆叠芘-苝二酰亚胺单共晶中的超快光驱动电荷转移激子动力学
DOI：
10.1039/d1tc04313g
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发表时间：
2021
影响因子：
6.4
通讯作者：
Wasielewski, Michael R.
中科院分区：
文献类型：
--
作者：
Myong, Michele S.;Qi, Yue;Stern, Charlotte;Wasielewski, Michael R.
电子供体-受体共晶因其许多有用的光电特性而受到越来越多的关注。虽然许多不同共晶的稳态特性已经被表征，但很少有研究涉及晶体形态如何影响电荷转移（CT）激子形成、迁移和衰变的动力学，而这通常对其在器件结构中的性能至关重要。在这里，我们表明芘（Pyr）电子给体分别与N,N'-双（2,6-二异丙基苯基）-或N,N'-双（3'-戊基）-苝-3,4:9,10-双（二甲酰亚胺）（diisoPDI或C5PDI）电子受体共结晶，分别产生混合的π堆叠Pyr-diisoPDI或Pyr-C5PDI供体-受体共晶。飞秒瞬态吸收显微镜用于确定这些单晶中的 CT 激子动力学。将数据拟合到一维电荷转移 CT 激子扩散模型显示，与 Pyr-C5PDI 共晶相比，Pyr-diisoPDI 共晶的扩散常数高出两个数量级。通过将共晶结构与其不同的激发态动力学相关联，阐明了每种混合堆叠结构对激子动力学的影响以及 CT 激子扩散的机制。
Electron donor–acceptor co-crystals are receiving increasing interest because of their many useful optoelectronic properties. While the steady-state properties of many different co-crystals have been characterized, very few studies have addressed how crystal morphology affects the dynamics of charge transfer (CT) exciton formation, migration, and decay, which are often critical to their performance in device structures. Here we show that co-crystallization of a pyrene (Pyr) electron donor with either N,N′-bis(2,6-diisopropylphenyl)- or N,N′-bis(3′-pentyl)-perylene-3,4:9,10-bis(dicarboximide) (diisoPDI or C5PDI) electron acceptors, respectively, yields mixed π-stacked Pyr–diisoPDI or Pyr–C5PDI donor–acceptor co-crystals. Femtosecond transient absorption microscopy is used to determine the CT exciton dynamics in these single crystals. Fitting the data to a one-dimensional charge transfer CT exciton diffusion model reveals a diffusion constant that is two orders of magnitude higher in the Pyr–diisoPDI co-crystal compared to the Pyr–C5PDI co-crystal. By correlating the co-crystal structures to their distinct excited-state dynamics, the effects of each mixed stacked structure on the exciton dynamics and the mechanisms of CT exciton diffusion are elucidated.