An external quantum efficiency of >20% from solution-processed poly(dendrimer) organic light-emitting diodes

Abstract

Efficient OLEDs from solution: engineering dipole alignment in polymers Dipole alignment is achieved in efficient solution-processed organic light-emitting diodes featuring a novel poly(dendrimer). A collaborative team led by Paul Burn from the Centre for Organic Photonics & Electronics, School of Chemistry & Molecular Biosciences at The University of Queensland have developed solution-processed organic light-emitting diodes (OLEDs) based on a phosphorescent poly(dendrimer)-based material with an out-coupling efficiency of around 40% and an external quantum efficiency of above 20%. The key to the enhanced light out-coupling in the devices is the favourable alignment of emissive dipoles in the poly(dendrimer), which consists of dendritic side-chains comprised of hole-transporting carbazole-based dendrons and iridium(III) complex-cores. The poly(dendrimer) is blended with a host material to ensure high efficiency in the device. Ultimately, the intelligent design of the developed poly(dendrimers) allowed the authors to utilise a simple bilayer device structure to demonstrate highly efficient solution-processed organic light-emitting diodes.