Experimental proof of Joule heating-induced switched-back regions in OLEDs

Kirch Anton; Fischer Axel; Liero Matthias; Fuhrmann Jürgen; Glitzky Annegret; Reineke Sebastian

doi:10.1038/s41377-019-0236-9

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Experimental proof of Joule heating-induced switched-back regions in OLEDs

Article

- Experimental proof of Joule heating-induced switched-back regions in OLEDs
- Light: Science & Applications Vol. 9, Issue 1, Pages: 42-51(2020)
- Affiliations：
  
  1.Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute of Applied Physics, Technische Universität Dresden, Nöthnitzer Straẞe 61, 01187 Dresden, Germany
  2.Weierstrass Institute Berlin, Mohrenstraẞe 39, 10117 Berlin, Germany
- Author bio：
  
  Axel Fischer (axel_fischer@tu-dresden.de)
- Funds：
- DOI：10.1038/s41377-019-0236-9
  CLC：
- Published：2020，
  
  Published Online：10 January 2020，
  
  Received：12 July 2019，
  
  Revised：06 December 2019，
  
  Accepted：12 December 2019
- Accepted：
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Kirch, A. et al. Experimental proof of Joule heating-induced switched-back regions in OLEDs. Light: Science & Applications, 9, 42–51 (2020).
DOI：

Kirch, A. et al. Experimental proof of Joule heating-induced switched-back regions in OLEDs. Light: Science & Applications, 9, 42–51 (2020). DOI： 10.1038/s41377-019-0236-9.

摘要

Abstract

Organic light-emitting diodes (OLEDs) have become a major pixel technology in the display sector

with products spanning the entire range of current panel sizes. The ability to freely scale the active area to large and random surfaces paired with flexible substrates provides additional application scenarios for OLEDs in the general lighting

automotive

and signage sectors. These applications require higher brightness and

thus

current density operation compared to the specifications needed for general displays. As extended transparent electrodes pose a significant ohmic resistance

OLEDs suffering from Joule self-heating exhibit spatial inhomogeneities in electrical potential

current density

and hence luminance. In this article

we provide experimental proof of the theoretical prediction that OLEDs will display regions of decreasing luminance with increasing driving current. With a two-dimensional OLED model

we can conclude that these regions are switched back locally in voltage as well as current due to insufficient lateral thermal coupling. Experimentally

we demonstrate this effect in lab-scale devices and derive that it becomes more severe with increasing pixel size

which implies its significance for large-area

high-brightness use cases of OLEDs. Equally

these non-linear switching effects cannot be ignored with respect to the long-term operation and stability of OLEDs; in particular

they might be important for the understanding of sudden-death scenarios.

关键词

Keywords

references

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