Engineering blue fluorescent bulk emitters for OLEDs: triplet harvesting by green phosphors

Simone Hofmann, Markus Hummert, Reinhard Scholz, Regina Luschtinetz, Caroline Murawski, Paul Anton Will, Susanne Hintschich, Jörg Alex, Vygintas Jankus, Andrew P Monkman, Björn Lüssem, Karl Leo, Malte Christian Gather

Research output: Contribution to journalArticlepeer-review

Abstract

Triplet harvesting in organic light-emitting diodes (OLEDs) from a blue fluorescent to a green phosphorescent emitter is important for the development of highly efficient white OLEDs for lighting applications. Here, we report new blue fluorescent bulk emitters with high triplet energies for triplet harvesting in OLEDs. Based on the chemical structure of the highly efficient blue emitter N,N′-di-1-naphthalenyl-N,N′-diphenyl-[1,1′:4′,1″:4″,1‴-quaterphenyl]-4,4‴
diamine (4P-NPD), two new quarterphenylene compounds are designed and
synthesized. Their experimentally obtained ionization potentials, singlet, and triplet levels are compared to quantum chemical calculations. We show that the incorporation of repulsive methyl groups leads to a twist of the outer phenyl rings of the molecule and increases the triplet level. Finally, triplet harvesting OLEDs comprising these two new compounds as bulk emittersare electrically and optically characterized. We demonstrate that both materials allow triplet harvesting by the green phosphorescent emitter iridium(III)bis(2-phenylpyridinato-N,C2′)acetylacetonate (Ir(ppy)2(acac)).

Original languageEnglish
Pages (from-to)2414-2426
JournalChemistry of Materials
Volume26
Issue number7
Early online date7 Mar 2014
DOIs
Publication statusPublished - 8 Apr 2014

Keywords

  • Organic light‐emitting diode
  • Triplet harvesting
  • Blue fluorescent emitter

Fingerprint

Dive into the research topics of 'Engineering blue fluorescent bulk emitters for OLEDs: triplet harvesting by green phosphors'. Together they form a unique fingerprint.

Cite this