Converting an organic light-emitting diode from blue to white with bragg modes

Konstantinos S. Daskalakis*, Francisco Freire-Fernández, Antti J. Moilanen, Sebastiaan Van Dijken, Päivi Törmä

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Organic light-emitting diodes (OLEDs) have been established as versatile light sources that allow for easy integration in large-area surfaces and flexible substrates. In addition, the low fabrication cost of OLEDs renders them particularly attractive as general lighting sources. Current methods for the fabrication of white-light OLEDs rely on the combination of multiple organic emitters and/or the incorporation of multiple cavity modes in a thick active medium. These architectures introduce formidable challenges in both device design and performance improvements, namely, the decrease of efficiency with increasing brightness (efficiency roll-off) and short operational lifetime. Here we demonstrate, for the first time, white-light generation in an OLED consisting of a sub-100 nm thick blue single-emissive layer coupled to the photonic Bragg modes of a dielectric distributed Bragg reflector (DBR). We show that the Bragg modes, although primarily located inside the DBR stack, can significantly overlap with the emissive layer, thus efficiently enhancing emission and outcoupling of photons at selected wavelengths across the entire visible light spectrum. Moreover, we show that color temperature can be tuned by the DBR parameters, offering great versatility in the optimization of white-light emission spectra.

Original languageEnglish
Pages (from-to)2655-2662
JournalACS Photonics
Volume6
Issue number11
DOIs
Publication statusPublished - 8 Oct 2019
MoE publication typeA1 Journal article-refereed

Keywords

  • distributed Bragg reflector
  • electroluminescence color conversion
  • Fabry-Pérot modes
  • organic semiconductors
  • white organic light-emitting diodes (WOLEDs)

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