Mechanical, Morphological, and Charge Transport Properties of NDI Polymers with Variable Built‐in Π‐Conjugation Lengths Probed by Simulation and Experiment
Mechanical, Morphological, and Charge Transport Properties of NDI Polymers with Variable Built‐in Π‐Conjugation Lengths Probed by Simulation and Experiment
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DOI：
10.1002/adfm.202310071
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发表时间：
2023-10
影响因子：
19
通讯作者：
Dan Zhao;Donghyun Kim;Sarbani Ghosh;Gang Wang;Wei Huang;Zonglong Zhu;T. J. Marks;Igor Zozoulenko;A. Facchetti
中科院分区：
文献类型：
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作者：
Dan Zhao;Donghyun Kim;Sarbani Ghosh;Gang Wang;Wei Huang;Zonglong Zhu;T. J. Marks;Igor Zozoulenko;A. Facchetti
可机械变形的聚合物半导体是制造柔性有机薄膜晶体管（FOTFT）的关键材料，FOTFT是电子电路和可穿戴电子设备的构建模块。然而，对于许多π共轭聚合物，实现机械变形性和有效的电荷传输仍然具有挑战性。在这里，聚合物主链弯曲刚度和膜微观结构对机械柔性和电荷传输的影响通过实验和计算方法研究了一系列具有不同π共轭程度的电子传输萘二酰亚胺（NDI）聚合物。结果显示，在完全π-共辄聚合物半导体PNDI-TVT 100（产生聚合物系列PNDI-TVTx，100 ≥ x ≥ 0）的主链中，用π-非共辄共聚单体二噻吩基乙烷（泰特）替代增加量的π-共辄共聚单体二噻吩基亚乙烯基（TVT）降低了主链刚性、织构化程度和NDI部分之间的π-π堆叠相互作用。重要的是，这种共聚单体取代增加了PNDI-TVTx的机械鲁棒性，同时保持了有效的电荷传输。因此，降低PNDI-TVTx的TVT含量抑制了膜裂纹的形成并显著稳定了弯曲时的场效应电子迁移率（例如，2 mm，超过2000次弯曲循环）。这项工作提供了一种调整π共轭聚合物中π-π堆叠的途径，同时提高FOTFT的机械柔性并保持良好的载流子迁移率。
Mechanically deformable polymeric semiconductors are a key material for fabricating flexible organic thin‐film transistors (FOTFTs)—the building block of electronic circuits and wearable electronic devices. However, for many π‐conjugated polymers achieving mechanical deformability and efficient charge transport remains challenging. Here the effects of polymer backbone bending stiffness and film microstructure on mechanical flexibility and charge transport are investigated via experimental and computational methods for a series of electron‐transporting naphthalene diimide (NDI) polymers having differing extents of π‐conjugation. The results show that replacing increasing amounts of the π‐conjugated comonomer dithienylvinylene (TVT) with the π‐nonconjugated comonomer dithienylethane (TET) in the backbone of the fully π‐conjugated polymeric semiconductor, PNDI‐TVT100 (yielding polymeric series PNDI‐TVTx, 100 ≥ x ≥ 0), lowers backbone rigidity, degree of texturing, and π–π stacking interactions between NDI moieties. Importantly, this comonomer substitution increases the mechanical robustness of PNDI‐TVTx while retaining efficient charge transport. Thus, reducing the TVT content of PNDI‐TVTx suppresses film crack formation and dramatically stabilizes the field‐effect electron mobility upon bending (e.g., 2 mm over 2000 bending cycles). This work provides a route to tune π–π stacking in π‐conjugated polymers while simultaneously promoting mechanical flexibility and retaining good carrier mobility in FOTFTs.