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Light Emission in the Unipolar Regime of Ambipolar Organic Field-Effect Transistors
Eindhoven University of Technology, Netherlands.
Eindhoven University of Technology, Netherlands.
Eindhoven University of Technology, Netherlands.
Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.ORCID iD: 0000-0002-7104-7127
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2013 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 23, no 33, 4133-4139 p.Article in journal (Refereed) Published
Abstract [en]

Light emission from ambipolar organic field-effect transistors (OFETs) is often observed when they are operated in the unipolar regime. This is unexpected, the light emission should be completely suppressed, because in the unipolar regime only one type of charge carrier is accumulated. Here, an electroluminescent diketopyrrolopyrrole copolymer is investigated. Local potential measurements by scanning Kelvin probe microscopy reveal a recombination position that is unstable in time due to the presence of injection barriers. The electroluminescence and electrical transport have been numerically analyzed. It is shown that the counterintuitive unipolar light emission is quantitatively explained by injection of minority carriers into deep tail states of the semiconductor. The density of the injected minority carriers is small. Hence they are relatively immobile and they recombine close the contact with accumulated majority carriers. The unipolar light output is characterized by a constant efficiency independent of gate bias. It is argued that light emission from OFETs predominantly originates from the unipolar regime when the charge transport is injection limited.

Place, publisher, year, edition, pages
Wiley-VCH Verlag , 2013. Vol. 23, no 33, 4133-4139 p.
Keyword [en]
light-emitting organic field-effect transistors; injection barrier; diketopyrrolopyrrole; recombination positions
National Category
Physical Sciences
URN: urn:nbn:se:liu:diva-118127DOI: 10.1002/adfm.201203568ISI: 000327492300010OAI: diva2:813839

Funding Agencies|NanoNextNL [06D.03]

Available from: 2015-05-25 Created: 2015-05-22 Last updated: 2015-06-04

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Kemerink, Martijn
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