Effects of Plasticizing Additives on Mechanical Properties of Semiconducting Polymers

Abstract

The study of deformable organic semiconductor materials has been in the spotlight in the next generation of flexible device technologies. In particular, organic semiconductor materials can take advantage of being lightweight, deformable, and capable of large-area processing as a solution process itself, compared to silicon and metal-based technologies that are currently available in commercial devices. A deformable and stretchable material must satisfy not only a certain level of electrical performance but also various mechanical properties. Since it has to withstand mechanical forces in the tensile or compression direction, it is desired to implement a material system with good tensile toughness. In this study, a plasticizer additive is blended with a highly crystalline donor-acceptor type polymer with excellent electrical performance to significantly improve mechanical tensile stretchability while ensuring electrical mobility. And the cause of mechanical change is to be analyzed by various methods such as morphology, crystallinity analysis, and thermodynamic analysis. In addition, we would like to find a way to minimize electrical performance degradation in tensile situation by manufacturing stretchable Organic field-effect transistors (OFETs). In Chapter 2, the first half of the study, we set up a measurement capable of the tensile properties of nanoscale thickness of polymer thin film, and conducted experiments on the process for data validity. In Chapter 3, using phthalate-based plasticizers, the tensile performance of the highly-crystalline conjugate polymer DPP-DTT blend film was increased by more than 10%. Then, the cause is to be found by suggesting molecular behavior in tensile situation, through the stress-strain curve according to the plasticizer content, crystallinity analysis, and thermodynamic analysis.