Conjugated Carbon Cyclic Nanorings as Additives for Intrinsically Stretchable Semiconducting Polymers

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.