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.