Molecular Origin of Strain‐Induced Chain Alignment in PDPP‐Based Semiconducting Polymeric Thin Films
Molecular Origin of Strain‐Induced Chain Alignment in PDPP‐Based Semiconducting Polymeric Thin Films
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DOI：
10.1002/adfm.202100161
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发表时间：
2021-03
影响因子：
19
通讯作者：
Song Zhang;Amirhadi Alesadi;Gage T. Mason;Kai‐Lin Chen;Guillaume Freychet;Luke A. Galuska;Yu‐Hsuan Cheng;P. B. J. St. Onge;Michael U. Ocheje;Guorong Ma;Zhiyuan Qian;Sujata Dhakal;Zachary Ahmad;Cheng Wang;Yu‐Cheng Chiu;S. Rondeau‐Gagné;W. Xia;X. Gu
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文献类型：
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作者：
Song Zhang;Amirhadi Alesadi;Gage T. Mason;Kai‐Lin Chen;Guillaume Freychet;Luke A. Galuska;Yu‐Hsuan Cheng;P. B. J. St. Onge;Michael U. Ocheje;Guorong Ma;Zhiyuan Qian;Sujata Dhakal;Zachary Ahmad;Cheng Wang;Yu‐Cheng Chiu;S. Rondeau‐Gagné;W. Xia;X. Gu
近几十年来，给体-受体（D-A）型半导体聚合物在可变形和可拉伸电子器件中显示出巨大的应用潜力。然而，由于其具有刚性主链和长增溶侧链的异质结构，其在机械变形后的分子图像的基本理解仍然缺乏调查。在这里，二酮基吡咯并吡咯（DPP）为基础的D-A聚合物薄膜的分子取向的拉伸变形下，通过实验测量和分子模拟探测。详细的形态学分析表明，高度对齐的聚合物微晶变形后，而主链对齐的程度是有限的结晶域内。此外，聚合物主链上的芳环平行于应变方向旋转，尽管相对较低的整体链各向异性。观察到侧链长度对DPP链排列的影响不太明显。这些观察结果与传统的直链半结晶聚合物（如聚乙烯）不同，这是由于DPP聚合物中主链/侧链组合的独特特征和晶体学特征。此外，从制造的有机场效应晶体管获得稳定且各向同性的电荷载流子迁移率。这项研究对薄膜微结构中不同组分的排列进行了解卷积，并强调了微晶旋转和链滑移是半导体聚合物的主要变形机制。
Donor–acceptor (D–A) type semiconducting polymers have shown great potential for the application of deformable and stretchable electronics in recent decades. However, due to their heterogeneous structure with rigid backbones and long solubilizing side chains, the fundamental understanding of their molecular picture upon mechanical deformation still lacks investigation. Here, the molecular orientation of diketopyrrolopyrrole (DPP)‐based D–A polymer thin films is probed under tensile deformation via both experimental measurements and molecular modeling. The detailed morphological analysis demonstrates highly aligned polymer crystallites upon deformation, while the degree of backbone alignment is limited within the crystalline domain. Besides, the aromatic ring on polymer backbones rotates parallel to the strain direction despite the relatively low overall chain anisotropy. The effect of side‐chain length on the DPP chain alignment is observed to be less noticeable. These observations are distinct from traditional linear‐chain semicrystalline polymers like polyethylene due to distinct characteristics of backbone/side‐chain combination and the crystallographic characteristics in DPP polymers. Furthermore, a stable and isotropic charge carrier mobility is obtained from fabricated organic field‐effect transistors. This study deconvolutes the alignment of different components within the thin‐film microstructure and highlights that crystallite rotation and chain slippage are the primary deformation mechanisms for semiconducting polymers.