Highly Efficient Microscopic Charge Transport within Crystalline Domains in a Furan‐Flanked Diketopyrrolopyrrole‐Based Conjugated Copolymer
Highly Efficient Microscopic Charge Transport within Crystalline Domains in a Furan‐Flanked Diketopyrrolopyrrole‐Based Conjugated Copolymer
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DOI：
10.1002/adfm.202000389
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发表时间：
2020-04
影响因子：
19
通讯作者：
Hisaaki Tanaka;S. Kawamura;P. Sonar;Y. Shimoi;T. Do;T. Takenobu
中科院分区：
文献类型：
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作者：
Hisaaki Tanaka;S. Kawamura;P. Sonar;Y. Shimoi;T. Do;T. Takenobu
阐明共轭聚合物薄膜中分子结构和电荷传输特性之间的相互关系是开发有机电子应用的高性能聚合物材料设计原理的一个重要问题。特别是，主链平面度被认为是控制传输性能的关键因素，特别是在最近开发的表现出高迁移率的供体-受体（D-A）型共聚物中，而通常仅在小晶域内实现的固有传输性能的直接评估很难通过使用传统的宏观测量来实现。在此，基于使用显微测量方法，证明 D-A 型共聚物 PDPPF-DTT 由共轭主链中的呋喃侧翼二酮吡咯并吡咯 (DPP) 和二噻吩并噻吩 (DTT) 单元组成，在结晶域内表现出高效的电荷传输性能，且活化能极低，低于 8 meV。 场诱导电子自旋共振光谱。这种高传输性能主要是由于通过引入呋喃侧翼的 DPP 和稠合二噻吩并噻吩单元实现的高主链平面度，这一点通过密度泛函理论计算得到了证明。该结果提供了当前分子设计产生平面主链并实现高效电荷传输性能的有效性的微观指示。
Elucidating the interrelation between the molecular structure and charge transport properties in conjugated polymer thin films is an essential issue in developing the design principle of high‐performance polymer materials for application in organic electronics. In particular, the backbone planarity is suggested to be a key element that governs the transport performance, especially in recently developed donor–acceptor (D–A)‐type copolymers exhibiting high mobility, whereas the direct evaluation of the intrinsic transport performance, usually realized only within the small crystalline domains, is difficult by using conventional macroscopic measurements. Here, it is demonstrated that a D–A type copolymer, PDPPF‐DTT, which consists of furan‐flanked diketopyrrolopyrrole (DPP) and dithienothiophene (DTT) units in the conjugated backbone, exhibits a highly efficient charge transport performance within the crystalline domains with a remarkably low activation energy of less than 8 meV, based on microscopic measurements using field‐induced electron spin resonance spectroscopy. This high transport performance is primarily caused by the high backbone planarity realized by introducing furan‐flanked DPP and fused dithienothiophene units, which is demonstrated from the density functional theory calculations. This result provides a microscopic indication of the effectiveness of the present molecular design to produce a planar backbone and realize highly efficient charge transport performance.