Highly Ambient-Stable Organic Thin-Film Transistors Fabricated Using Naphthalene Diimide and Thienylene–Vinylene–Thienylene-Based n-Type Polymers with Different Electron-Withdrawing Groups

Abstract

We designed, synthesized, and characterized a series of naphthalene diimide (NDI)-based polymers with pristine (H)-, fluorine (F)-, chlorine (Cl)-, and cyano (CN)-substituted thienylene−vinylene−thienylene (TVT) moieties. The theoretical and experimental results showed that a stronger electron-withdrawing group in the TVT unit reduces the energy of the lowest unoccupied molecular orbital (LUMO), which could enhance the air stability of NDI-based organic thin-film transistors (OTFTs). However, this improved stability was accompanied by a reduction in electron mobility to various degrees. The reason is that the F, Cl, and CN moieties increased the dihedral angles in the polymer structure and raised the activation energy and the width of density of states (DOS) in the device systems. We believe that a clear understanding of the mechanism will assist in the design of nchannel OTFTs with both high mobility and high ambient stability.

Current developments of eco-friendly organic field-effect transistors: from molecular engineering of organic semiconductors to greener device processing

“…Various cases for improving solubility or maximizing the performance of semiconductor materials by introducing diverse substituents into the semiconductor molecules have been reported, but many of these semiconductor materials were produced by being processed using a chlorine-based solvent. 97–101 Therefore, in describing the strategy of introducing substituents into the backbone, only cases using non-chlorinated solvents are reviewed. Ye and co-workers deployed an oxetane group as a substituent of polythiophenes (PTs), a representative class of p-type OSCs (PTHOT), to improve the solubility of the PTs in environmentally friendly solvents.…”