Abstract
Electron- and hole-transport properties of the -type copolymer poly[,-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 m/V s for electrons and 3.4 10 m/V s 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.
4 More- Received 4 August 2012
DOI:https://doi.org/10.1103/PhysRevB.86.165203
©2012 American Physical Society
Synopsis
Asymmetry in Mobility
Published 18 October 2012
Experimental data in combination with calculations show why some organic semiconductors have intrinsically different mobilities for electrons and holes.
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