Efficient near-infrared organic radical-based light-emitting diodes

Abstract

Despite extensive research on near-infrared organic light-emitting diodes (OLEDs), the external quantum efficiency (EQE) of these devices are far lower than devices with visible light emission. Recently, doublet fluorescent emission from organic radicals has emerged as a new route to more efficient light-emitting devices than those using established non-radical organic emitters. Charge recombination in radical devices results in doublet excitons with nanosecond emission and avoids the efficiency limit usually associated with singlets and triplets. For the application of the organic radicals to near-infrared electroluminescence, the novel near-infrared radical emitter showing around 800 nm emission was designed. Using the organic radical, not only higher than 5% EQE was attained but also the efficiency roll-off and operational lifetime were substantially improved in addition to decreasing turn-on and driving voltage significantly.