Efficiency enhancement of organic light-emitting diodes incorporating a highly oriented thermally activated delayed fluorescence emitter

Christian Mayr, Sae Youn Lee, Tobias D. Schmidt, Takuma Yasuda, Chihaya Adachi, Wolfgang Brütting

Research output: Contribution to journalArticle

107 Citations (Scopus)

Abstract

An organic light-emitting diode (OLED) with the blue emitter CC2TA showing thermally activated delayed fluorescence (TADF) is presented exhibiting an external quantum efficiency (ηEQE) of 11% ± 1%, which clearly exceeds the classical limit for fluorescent OLEDs. The analysis of the emission layer by angular dependent photoluminescence (PL) measurements shows a very high degree of 92% horizontally oriented transition dipole moments. Excited states lifetime measurements of the prompt fluorescent component under PL excitation yield a radiative quantum efficiency of 55% of the emitting species. Thus, the radiative exciton fraction has to be significantly higher than 25% due to TADF. Performing a simulation based efficiency analysis for the OLED under investigation allows for a quantification of individual contributions to the efficiency increase originating from horizontal emitter orientation and TADF. Remarkably, the strong horizontal emitter orientation leads to a light-outcoupling efficiency of more than 30%.

Original languageEnglish
Pages (from-to)5232-5239
Number of pages8
JournalAdvanced Functional Materials
Volume24
Issue number33
DOIs
Publication statusPublished - Sep 3 2014

Fingerprint

Organic light emitting diodes (OLED)
emitters
light emitting diodes
Fluorescence
Quantum efficiency
fluorescence
augmentation
quantum efficiency
Photoluminescence
photoluminescence
Dipole moment
Electron transitions
Excited states
Excitons
excitation
dipole moments
excitons
life (durability)
simulation

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Condensed Matter Physics
  • Electrochemistry

Cite this

Efficiency enhancement of organic light-emitting diodes incorporating a highly oriented thermally activated delayed fluorescence emitter. / Mayr, Christian; Lee, Sae Youn; Schmidt, Tobias D.; Yasuda, Takuma; Adachi, Chihaya; Brütting, Wolfgang.

In: Advanced Functional Materials, Vol. 24, No. 33, 03.09.2014, p. 5232-5239.

Research output: Contribution to journalArticle

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AU - Brütting, Wolfgang

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