Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA.
Department of Chemistry, Stanford University, Stanford, CA, 94305, USA.
Adv Mater. 2019 Oct;31(42):e1903912. doi: 10.1002/adma.201903912. Epub 2019 Sep 6.
Molecular additives are often used to enhance dynamic motion of polymeric chains, which subsequently alter the functional and physical properties of polymers. However, controlling the chain dynamics of semiconducting polymer thin films and understanding the fundamental mechanisms of such changes is a new area of research. Here, cycloparaphenylenes (CPPs) are used as conjugated molecular additives to tune the dynamic behaviors of diketopyrrolopyrrole-based (DPP-based) semiconducting polymers. It is observed that the addition of CPPs results in significant improvement in the stretchability of the DPP-based polymers without adversely affecting their mobility, which arises from the enhanced polymer dynamic motion and reduced long-range crystalline order. The polymer films retain their fiber-like morphology and short-range ordered aggregates, which leads to high mobility. Fully stretchable transistors are subsequently fabricated using CPP/semiconductor composites as active layers. These composites are observed to maintain high mobilities when strained and after repeated applied strains. Interestingly, CPPs are also observed to improve the contact resistance and charge transport of the fully stretchable transistors. ln summary, these results collectively indicate that controlling the dynamic motion of polymer semiconductors is proved to be an effective way to improve their stretchability.
分子添加剂通常用于增强聚合物链的动态运动，从而改变聚合物的功能和物理性质。然而，控制半导体聚合物薄膜的链动力学并理解这种变化的基本机制是一个新的研究领域。在这里，环方苯（CPPs）被用作共轭分子添加剂来调节基于二酮吡咯并吡咯（DPP 基）半导体聚合物的动态行为。观察到 CPPs 的添加导致 DPP 基聚合物的拉伸性显著提高，而不会对其迁移率产生不利影响，这是由于聚合物动态运动增强和长程结晶有序度降低所致。聚合物薄膜保留了纤维状形态和短程有序聚集，从而具有高迁移率。随后使用 CPP/半导体复合材料作为有源层来制造完全可拉伸晶体管。观察到这些复合材料在应变时和在重复施加应变后保持高迁移率。有趣的是，CPPs 还被观察到可以改善完全可拉伸晶体管的接触电阻和电荷输运。总之，这些结果表明，控制聚合物半导体的动态运动被证明是提高其拉伸性的有效方法。
