Highly Efficient Top-Emitting Quantum-Dot Light-Emitting Diodes with Record-Breaking External Quantum Efficiency of over 44.5%

Top-emitting (TE) quantum-dot light-emitting diodes (QLEDs) can exhibit higher light outcoupling efficiency (OCE) compared to bottom-emitting (BE) QLEDs due to the eliminated substrate mode and enhanced microcavity effect. In this study, TE QLEDs with an OCE of over 45% are realized by simultaneously optimizing the thicknesses of both indium-zinc-oxide (IZO) phase tuning layers and IZO top transparent electrodes. To reduce the resistance, the IZO top electrodes are equipped with an auxiliary metal electrode. Consequently, the red QLEDs demonstrate a high external quantum efficiency (EQE) of 38.2%. Furthermore, by applying a scattering layer on the IZO top electrode, the red QLEDs demonstrate record-breaking efficiencies of EQE 44.5%, power efficiency 92.2 lm W −1 , and current efficiency 93.7 cd A −1 . The proposed device architecture and optimization strategy contribute to a new design scheme for the preparation of highly efficient QLEDs for displays and lighting applications.