Ultrahigh Efficiency Fluorescent Single and Bi-Layer Organic Light Emitting Diodes: The Key Role of Triplet Fusion

Research output: Contribution to journalArticle

DOI

Authors

  • Chien-Jung Chiang
  • Alpay Kimyonok
  • Marc K. Etherington
  • Gareth C. Griffiths
  • Vygintas Jankus
  • Figen Turksoy
  • Andy P. Monkman

External departments

  • Durham University

Details

Original languageEnglish
Pages (from-to)739-746
JournalAdvanced Functional Materials
Volume23
Issue number6
Early online date24 Sep 2012
DOIs
Publication statusPublished - 11 Feb 2013
Publication type

Research output: Contribution to journalArticle

Abstract

A new family of anthracene core, highly fluorescent emitters is synthesized which include diphenylamine hole transport end groups. Using a very simple one or two layer organic light emitting diode (OLED) structure, devices without outcoupling achieve an external quantum efficiency of 6% and photonic efficiencies of 20 cd/A. The theoretical maximum efficiency of such devices should not exceed 3.55%. Detailed photophysical characterization shows that for these anthracene based emitters 2T1≤Tn and so in this special case, triplet fusion can achieve a singlet production yield of 0.5. Indeed, delayed electroluminescence measurements show that triplet fusion contributes 59% of all singlets produced in these devices. This demonstrates that when triplet fusion becomes very efficient, fluorescent OLEDs even with very simple structures can approach an internal singlet production yield close to the theoretical absolute maximum of 62.5% and rival phosphorescent‐based OLEDs with the added advantage of much improved stability.