High-performance thermally activated delayed fluorescence organic light-emitting diodes with a wide gap phosphorescent complex as a sensitizer

Abstract

In this work, we demonstrated the high performance of an electroluminescent (EL) device based on an orange-yellow thermally activated delayed fluorescence emitter (TXO-TPA) by utilizing an iridium complex (FK306) as a sensitizer. Compared with reference devices without FK306, these co-doped devices displayed significant EL performance enhancement, which could be attributed to an optimized carrier distribution and efficient energy transfer. In addition, the presence of FK306 molecules broadened the exciton formation zone in emitting layer 2 (EML2), thus suppressing the quenching of triplet excitons. Finally, the optimized co-doped double-EML device obtained superior EL performance with maximum current efficiency, power efficiency, and external quantum efficiency values of up to 58.94 cd A⁻¹, 61.69 lm W⁻¹, and 16.5%, respectively. Even at a high brightness of 1000 cd m⁻², an EL efficiency as high as 12.67 cd A⁻¹ was retained by the same device.