Lin Yan-Cheng, Huang Yen-Wen, Hung Chih-Chien, Chiang Yun-Chi, Chen Chun-Kai, Hsu Li-Che, Chueh Chu-Chen, Chen Wen-Chang
Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
Advanced Research Center for Green Materials Science and Technology, National Taiwan University, Taipei 10617, Taiwan.
ACS Appl Mater Interfaces. 2020 Nov 11;12(45):50648-50659. doi: 10.1021/acsami.0c14592. Epub 2020 Nov 2.
Conjugated polymers synthesized through random terpolymerization have recently attracted great research interest due to the synergetic effect on the polymer's crystallinity and semiconducting properties. Several studies have demonstrated the efficacy of random terpolymerization in fine-tuning the aggregation behavior and optoelectronic property of conjugated polymers to yield enhanced device performance. However, as an influential approach of backbone engineering, its efficacy in modulating the mobility-stretchability property of high-performance conjugated polymers has not been fuller explored to date. Herein, a series of random terpolymers based on the diketopyrrolopyrrole-bithiophene (DPP-2T) backbone incorporating different amounts of isoindigo (IID) unit are synthesized, and their structure-mobility-stretchability correlation is thoroughly investigated. Our results reveal that random terpolymers containing a low IID content (DPP95 and DPP90) show enhanced interchain packing and solid-state aggregation to result in improved charge-transporting performance (can reach 4 order higher) compared to the parent polymer DPP100. In addition, owing to the enriched amorphous feature, DPP95 and DPP90 deliver an improved orthogonal mobility (μ) of >0.01 cm V s under a 100% strain, higher than the value (∼0.002 cm V s) of DPP100. Moreover, DPP95 even yields 20% enhanced orthogonal μ retention after 800 stretching-releasing cycles with 60% strain. As concluded from a series of analyses, the improved mobility-stretchability property exerted by random terpolymerization arises from the enriched amorphous feature and enhanced aggregation behavior imposed by the geometry mismatch between different acceptors (DPP and IID). This study demonstrates that backbone engineering through rational random terpolymerization not only enhances the mobility-stretchability of a conjugated polymer but also realizes a better mechanical endurance, providing a new perspective for the design of high-performance stretchable conjugated polymers.
通过无规三元共聚合成的共轭聚合物，由于其对聚合物结晶度和半导体性能的协同效应，最近引起了极大的研究兴趣。多项研究已证明无规三元共聚在微调共轭聚合物的聚集行为和光电性能以提高器件性能方面的有效性。然而，作为主链工程的一种有影响力的方法，其在调节高性能共轭聚合物的迁移率-拉伸性方面的有效性迄今为止尚未得到充分探索。在此，合成了一系列基于二酮吡咯并吡咯-联噻吩（DPP-2T）主链并包含不同量异吲哚酮（IID）单元的无规三元共聚物，并对其结构-迁移率-拉伸性相关性进行了深入研究。我们的结果表明，与母体聚合物DPP100相比，含有低IID含量的无规三元共聚物（DPP95和DPP90）表现出增强的链间堆积和固态聚集，从而导致电荷传输性能得到改善（可提高4个数量级）。此外，由于富含非晶态特征，DPP95和DPP90在100%应变下具有大于0.01 cm² V⁻¹ s⁻¹的改进的正交迁移率（μ），高于DPP100的值（约0.002 cm² V⁻¹ s⁻¹）。此外，DPP95在60%应变下经过800次拉伸-释放循环后，正交μ保留率甚至提高了20%。从一系列分析得出的结论是，无规三元共聚所带来的迁移率-拉伸性的改善源于不同受体（DPP和IID）之间的几何失配所导致的富含非晶态特征和增强的聚集行为。这项研究表明，通过合理的无规三元共聚进行主链工程不仅可以提高共轭聚合物的迁移率-拉伸性，还可以实现更好的机械耐久性，为高性能可拉伸共轭聚合物的设计提供了新的视角。
