title: Polyethylenimine (PEI) As an Effective Dopant To Conveniently Convert Ambipolar and p-Type Polymers into Unipolar n-Type Polymers.
abstract: In this study, we added a small amount of polyethylenimine (PEI) into several ambipolar and p-type polymer semiconductors and used these blends as channel materials in organic thin film transistors (OTFTs). It is found that PEI can effectively suppress hole transport characteristics while maintaining or promoting the electron transport performance. Unipolar n-channel OTFTs with electron-only transport behavior is achieved for all the polymer semiconductors chosen with 2-10 wt % PEI. The electron-rich nitrogen atoms in PEI are thought to fill the electron traps, raise the Fermi level and function as trapping sites for holes, leading to promotion of electron transport and suppression of hole transport. This work demonstrates a convenient general approach to transforming ambipolar and p-type polymer semiconductors into unipolar n-type polymer semiconductors that are useful for printed logic circuits and many other applications.
authors.forename: Bin
authors.initials: B
authors.lastname: Sun
authors.forename: Wei
authors.initials: W
authors.lastname: Hong
authors.affiliation: Department of Materials Science and Engineering, University of Toronto , 184 College Street, Toronto, Ontario M5S 3E4, Canada.
authors.forename: Emmanuel S
authors.initials: ES
authors.lastname: Thibau
authors.forename: Hany
authors.initials: H
authors.lastname: Aziz
authors.affiliation: Department of Materials Science and Engineering, University of Toronto , 184 College Street, Toronto, Ontario M5S 3E4, Canada.
authors.forename: Zheng-Hong
authors.initials: ZH
authors.lastname: Lu
authors.forename: Yuning
authors.initials: Y
authors.lastname: Li
keywords: ambipolar; n-type; organic thin film transistors; polarity conversion; polymer semiconductors