Highly efficient and stable blue organic light-emitting diodes through the selective quenching of long-living triplet exciton of a thermally activated delayed fluorescence emitter

Abstract

In the organic light-emitting diodes (OLEDs), the achievement of high efficiency and long device lifetime has been a goal due to the short device lifetime of the high efficiency blue OLED devices. The strategy for the device structure in this study suggests a solution for high efficiency and long lifetime of blue thermally activated delayed fluorescent (TADF) OLEDs by selectively managing the long-living triplet excitons of TADF emitters mainly responsible for the short lifetime of TADF OLEDs. The introduction of a triplet exciton quenching layer (QL) positioned at a short distance from the recombination zone could quench the long-living triplet excitons of TADF emitters and dramatically enhance the device lifetime of TADF OLEDs without efficiency loss. Ultimately, the device lifetime was doubled while achieving a high external quantum efficiency of 22.0% compared to the conventional TADF OLED by selective quenching long-living triplet exciton. This study verifies the potential of QL in TADF OLEDs as a future strategy to achieve high efficiency and long lifetime in the blue OLEDs.