용액공정 가능한 랜덤 공중합체 기반 고성능 유기 트랜지스터에 관한 연구

Abstract

High-performance organic field-effect transistors (OFETs) have been realized through many efforts such as development of materials and optimization of fabrication process. π‒Conjugated donor-acceptor copolymers have been utilized as semiconductor layers due to their effective charge-transport ability. However, most of the solution-processable OFETs are fabricated using eco-harmful chlorinated solvents resulting in serious environmental pollution and diseases because of a good solubility for polymers. In addition, achieving high-stable n-channel OFETs is very challenging because of the high-lying LUMO energy levels of n-channel organic semiconductors. In this work, firstly, eco-friendly solution-processable OFETs was realized using the set of diketopyrrolopyrrole (DPP)-based random copolymers including two donor units, dithienylvinylene (TVT) and selenophene (Se) by controlling irregularity of polymer backbone. The remarkable charge mobility was obtained from 2-methyltetrafuran-processed OFETs compared to chlorobenzene-processed ones. Secondly, the air stability of n-channel OFETs was dramatically improved by fluorinating NDI-based copolymers because F substituents decrease LUMO energy levels of the polymers. Fully fluorinated copolymer-based OFET has worked for more than 90 days, while non-fluorinated one does only 4 days. These studies have shown a technical feasibility of high-performance, high-stable, eco-friendly OFETs. In addition, they have provided a basic understanding of OFETs.