Development of polymer-based functional dielectric layers to control electrical properties of organic electronic devices

Abstract

Organic electronics have attracted significant research interest for future flexible and wearable electronics due to their flexibility, lightweight, and cost-effectiveness. Among them, an organic thin film transistor (OTFT) is considered as a building block which can be used as an electrical switch in various electronic systems. To realize flexible and high-performance OTFTs, it is necessary to develop flexible dielectric layers with excellent insulating properties since the dielectric layer is the key component for OTFT operation. Furthermore, the surface and bulk properties of the dielectric layer can strongly affect not only operating voltage but also other electrical properties such as mobility and threshold voltage ($V_T$) in OTFTs. This thesis intended to develop new functional dielectric layers to control the electrical properties of organic electronic devices. Here, an initiated chemical vapor deposition (iCVD) process was utilized as a synthesis tool for polymer-based functional dielectric layers. The iCVD process enables the highly conformal and uniform deposition of polymeric films and homogeneous copolymerization without phase segregation thanks to its surface-growing mechanism. By incorporating polar functionalities into the polymer matrix or stacking polymer dielectric layers via the iCVD process, various polymer-based funcntional dielectric layers were newly synthesized and applied to OTFTs. The effect of the developed functional dielectric layer on the electrical properties of the devices were also verified. As a result, the electrical properties of organic electronic devices could be delicately tuned, leading to high-performance organic electronic devices with low power consumption. These results provide an understanding about the effect of the dielectric layers on device performance in OTFTs and may open up a new pathway towards optimization and improvement of electrical properties in various organic electronics. Therefore, this thesis presents an important milestone in the development and realization of high-performance and flexible organic electronics for future electronics.