• Puttock, Emma
• Chandra Raju Nagiri, Ravi
• Mcewan, Jake
• Burn, Paul
• Namdas, Ebinazar
• Bown, Mark
• Shaw, Paul
• Maasoumi, Pegah
• Jansen-Van Vuuren, Ross
• Oconnell, Jenny

Abstract

Controlling the orientation of the emissive dipole has led to a renaissance of organic light-emitting diode (OLEDs) research, with external quantumefficiencies (EQEs) of >30% being reported for phosphorescent emitters. These highly efficient OLEDs are generally manufactured using evaporative methods and are comprised of small molecule heteroleptic phosphorescent iridium(III) complexes blended with a host and additional layers to balance charge injection and transport. Large area OLEDs for lighting and display applications would benefit from low cost solution-processing, providing high EQEs could be achieved. Here we show that poly(dendrimer)s consisting of a nonconjugated polymer backbone with iridium(III) complexes forming the cores of first generation dendrimer side chains can be co-deposited with a host by solution processing to give highly efficient devices. Simple bilayer devices comprising the emissive layer and an electron transport layer gave an EQE of >20% at brightnesses of up to ≈300 cd/m2, showing that polymer engineering can enable alignment of the emissive dipole of solution-processed phosphorescent materials.

Topics

• polymer
• forming
• dendrimer
• solution processing
• Iridium