Novel Quinoidal Conjugated Molecules and Polymers for High Performance Organic Field-Effect Transistors

Abstract

Organic field-effect transistors (OFETs) based on organic semiconducting materials have intensive interest both in the academic and industrial fields because of their application in low-cost and flexible electronics. The structure-property relationship of novel organic semiconducting materials has been explored with the development of device engineering technique leading to understanding charge transport mechanism and device physics. In this work, we have focused on the investigation of structure-property relationship of conjugated molecules based on quinoidal structure. The quinoidal structure has been considered as a promising building block to achieve efficient charge transport due to their high structural planarity arising from a double bond linkage between aromatic rings. Despite the merits as conjugated moiety, the incorporation of the quinoidal platform into the conjugated polymer backbones has suffered synthetic difficulty. Here, some derivatives of quinoidal small molecules and polymers with various quinoidal platforms were synthesized, and their structure-property relationship was investigated. Moreover, field-effect transistors based on these compounds were fabricated and characterized about electrical properties. Among them, OFETs based on poly(quinoidal thiophene-bithiophene) (PQuT-BT) prepared by off-center spinning showed the unprecedent highest hole mobility of 8.09 cm2 V-1 s-1 among reported quinoidal polymers. Furthermore, we fabricated OFET devices based on this polymer via printing methods applying unidirectional shear forces leading to high molecular alignment and device uniformity in large area.