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.
Perovskite light-emitting diodes (PeLEDs) exhibit remarkable potential in the field of displays and solid-state lighting. However, blue PeLEDs, a key element for practical applications, still lag behind their green and red counterparts, due to a combination of strong nonradiative recombination losses and unoptimized device structures. In this report, we propose a buried interface modification strategy to address these challenges by focusing on the bottom-hole transport layer (HTL) of the PeLEDs. On the one hand, a multifunctional molecule, aminoacetic acid hydrochloride (AACl), is introduced to modify the HTL/perovskite interface to regulate the perovskite crystallization. Experimental investigations and theoretical calculations demonstrate that AACl can effectively reduce the nonradiative recombination losses in bulk perovskites by suppressing the growth of low- n perovskite phases and also the losses at the bottom interface by passivating interfacial defects . On the other hand, a self-assembly nanomesh structure is ingeniously developed within the HTLs. This nanomesh structure is meticulously crafted through the blending of poly-(9,9-dioctyl-fluorene-co-N-(4-butyl phenyl) diphenylamine) and poly (n-vinyl carbazole), significantly enhancing the light outcoupling efficiency in PeLEDs. As a result, our blue PeLEDs achieve remarkable external quantum efficiencies , 20.4% at 487 nm and 12.5% at 470 nm, which are among the highest reported values. Our results offer valuable insights and effective methods for achieving high-performance blue PeLEDs.
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