WIAS Preprint No. 2420, (2017)

3D electrothermal simulations of organic LEDs showing negative differential resistance



Authors

  • Liero, Matthias
    ORCID: 0000-0002-0963-2915
  • Fuhrmann, Jürgen
    ORCID: 0000-0003-4432-2434
  • Glitzky, Annegret
  • Koprucki, Thomas
    ORCID: 0000-0001-6235-9412
  • Fischer, Axel
  • Reineke, Sebastian

2010 Mathematics Subject Classification

  • 35Q79 35J92 80M12

2008 Physics and Astronomy Classification Scheme

  • 72.20.Pa, 72.80.Le, 81.05.Fb, 85.80.Fi, 02.60.Cb

Keywords

  • organic semiconductors, self-heating, negative differential resistance, p-Laplacian, thermistor model, hybrid finite-volume/finite-element scheme

DOI

10.20347/WIAS.PREPRINT.2420

Abstract

Organic semiconductor devices show a pronounced interplay between temperature-activated conductivity and self-heating which in particular causes inhomogeneities in the brightness of large-area OLEDs at high power. We consider a 3D thermistor model based on partial differential equations for the electrothermal behavior of organic devices and introduce an extension to multiple layers with nonlinear conductivity laws, which also take the diode-like behavior in recombination zones into account. We present a numerical simulation study for a red OLED using a finite-volume approximation of this model. The appearance of S-shaped current-voltage characteristics with regions of negative differential resistance in a measured device can be quantitatively reproduced. Furthermore, this simulation study reveals a propagation of spatial zones of negative differential resistance in the electron and hole transport layers toward the contact.

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