Asymmetric electron and hole transport in a high-mobility n-type conjugated polymer

Gert Jan A.H. Wetzelaer, Martijn Kuik, Yoann Olivier, Vincent Lemaur, Jérôme Cornil, Simone Fabiano, Maria Antonietta Loi, Paul W.M. Blom

Research output: Contribution to journalArticle

Abstract

Electron- and hole-transport properties of the n-type copolymer poly{[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2, 6-diyl]-alt-5,5′-(2,2′-dithiophene)} [P(NDI2OD-T2), PolyeraActivInk™ N2200] are investigated. Electron- and hole-only devices with Ohmic contacts are demonstrated, exhibiting trap-free space-charge-limited currents for both types of charge carriers. While hole and electron mobilities are frequently equal in organic semiconductors, room-temperature mobilities of 5 × 10 -8 m2/Vs for electrons and 3.4 × 10 -10 m2/Vs for holes are determined, both showing universal Arrhenius temperature scaling. The origin of the large difference between electron and hole mobility is explained by quantum-chemical calculations, which reveal that the internal reorganization energy for electrons is smaller than for holes, while the transfer integral is larger. As a result, electron transport is intrinsically superior to hole transport under the same injection and extraction conditions.

Original languageEnglish
Article number165203
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume86
Issue number16
DOIs
Publication statusPublished - 18 Oct 2012
Externally publishedYes

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