Frequency-domain time-resolved luminescence for in-operando study of efficiency roll-off in organic light-emitting diodes

Liam G. King*, Kou Yoshida*, Ifor D.W. Samuel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Time-resolved luminescence measurements are invaluable for understanding light-emitting materials but are difficult to perform on operating organic light-emitting diodes (OLEDs) because the light generated by the OLED can disturb common time-resolved techniques. We show that frequency-domain luminescence can be used to overcome this problem, and apply it to study efficiency roll-off in OLEDs. We measure the exciton lifetime of a phosphorescent OLED based on the emitter bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate) iridium(III) (Ir(MDQ)2(acac)) whilst it is operating. By driving the OLED continuously at current densities of up to 128mA/cm2, we observe that the exciton lifetime decreases with increasing current density as a result of triplet-polaron annihilation (TPA). The measurement presented can guide the development of new materials and device structures with improved efficiency at high brightness.
Original languageEnglish
Article number117489
JournalSynthetic Metals
VolumeIn press
DOIs
Publication statusAccepted/In press - 23 Oct 2023

Keywords

  • Phosphorescence
  • Photoluminescence lifetime
  • Fluorimetry
  • OLED
  • Triplet-polaron annihilation

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