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The role of diffusion on SCLC transport in double injection devices

Neumann, Frederik and Genenko, Yuri A. and Schmechel, Roland and Seggern, Heinz von (2005):
The role of diffusion on SCLC transport in double injection devices.
In: Synthetic metals, Elsevier Science Publishing, pp. 291-296, 150, (3), [Online-Edition: http://www.sciencedirect.com/science/article/pii/S0379677905...],
[Article]

Abstract

A theoretical study of SCLC transport in double injection insulators is presented. It will be demonstrated, that the inclusion of charge carrier diffusion, neglected in many previous studies of transport in organic light emitting diodes (OLEDs), is essential to obtain physical meaningful spatial charge carrier densities and field distributions. Only the knowledge of such correct spatial distributions enables one to compute the correct position of the charge carrier recombination zone. In previous calculations without diffusion the recombination process often takes place in the vicinity of both electrodes, even for equal mobilities of holes and electrons. In the present calculation including diffusion it is demonstrated that only one recombination zone exists. For equal mobilities of electrons and holes the recombination zone is found as expected in the centre of the device whereas for different mobility values it may be strongly shifted to one of the electrodes. The resulting I–V characteristics indicate that, in double injection devices, the well-known Mott–Gurney law holds only at sufficiently high voltages and only if recombination is taken into account. For small voltages, an ohmic-like behavior is observed in any case, however, if no recombination is assumed a transition to an I ∼ V3 law is obtained for higher voltages. Due to the inclusion of diffusion, all I–V characteristics exhibit temperature dependence.

Item Type: Article
Erschienen: 2005
Creators: Neumann, Frederik and Genenko, Yuri A. and Schmechel, Roland and Seggern, Heinz von
Title: The role of diffusion on SCLC transport in double injection devices
Language: English
Abstract:

A theoretical study of SCLC transport in double injection insulators is presented. It will be demonstrated, that the inclusion of charge carrier diffusion, neglected in many previous studies of transport in organic light emitting diodes (OLEDs), is essential to obtain physical meaningful spatial charge carrier densities and field distributions. Only the knowledge of such correct spatial distributions enables one to compute the correct position of the charge carrier recombination zone. In previous calculations without diffusion the recombination process often takes place in the vicinity of both electrodes, even for equal mobilities of holes and electrons. In the present calculation including diffusion it is demonstrated that only one recombination zone exists. For equal mobilities of electrons and holes the recombination zone is found as expected in the centre of the device whereas for different mobility values it may be strongly shifted to one of the electrodes. The resulting I–V characteristics indicate that, in double injection devices, the well-known Mott–Gurney law holds only at sufficiently high voltages and only if recombination is taken into account. For small voltages, an ohmic-like behavior is observed in any case, however, if no recombination is assumed a transition to an I ∼ V3 law is obtained for higher voltages. Due to the inclusion of diffusion, all I–V characteristics exhibit temperature dependence.

Journal or Publication Title: Synthetic metals
Volume: 150
Number: 3
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: Organic light emitting diodes, Simulation, Diffusion, Space charge limited current
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Electronic Materials
11 Department of Materials and Earth Sciences > Material Science > Materials Modelling
Zentrale Einrichtungen
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > C - Modelling
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > C - Modelling > Subproject C5: Phenomenological modelling of injection, transport and recombination in organic semiconducting devices as well as in inorganic ferroelectric materials
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > D - Component properties
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > D - Component properties > Subproject D4: Fatigue of organic electronic devices
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres
DFG-Collaborative Research Centres (incl. Transregio)
Date Deposited: 20 Nov 2008 08:22
Official URL: http://www.sciencedirect.com/science/article/pii/S0379677905...
Additional Information:

SFB 595 Cooperation C5, D4

License: [undefiniert]
Funders: This work was supported by the Deutsche Forschungsgemeinschaft through the Sonderforschungsbereich 595.
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