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 language | English |
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Pages (from-to) | 2414-2426 |
Journal | Chemistry of Materials |
Volume | 26 |
Issue number | 7 |
Early online date | 7 Mar 2014 |
DOIs | |
Publication status | Published - 8 Apr 2014 |
Keywords
- Organic light‐emitting diode
- Triplet harvesting
- Blue fluorescent emitter