Perovskite Light-Emitting Diodes with an External Quantum Efficiency Exceeding 30.

TL;DR: In this article , a super high-efficiency green perovskite light-emitting diodes (PeLEDs) were constructed by balancing the electron-hole recombination and enhancing the light outcoupling.

Abstract: Perovskite light-emitting diodes (PeLEDs) are strong candidates for next-generation display and lighting technologies due to their high color purity and low-cost solution-processed fabrication. However, PeLEDs are not superior to commercial organic light-emitting diodes (OLEDs) in efficiency, as some key parameters affecting their efficiency, such as the charge carrier transport and light outcoupling efficiency, are usually overlooked and not well optimized. Here, we report ultrahigh-efficiency green PeLEDs with quantum efficiencies surpassing a milestone of 30% by regulating the charge carrier transport and near-field light distribution to reduce electron leakage and achieve a high light outcoupling efficiency of 41.82%. We apply Ni0.9 Mg0.1 Ox films with a high refractive index and increased hole carrier mobility as the hole injection layer to balance the charge carrier injection and insert the polyethylene glycol layer between the hole transport layer and the perovskite emissive layer to block the electron leakage and reduce the photon loss. Therefore, with the modified structure, the state-of-the-art green PeLEDs achieve a world-record external quantum efficiency of 30.84% (average  =  29.05 ± 0.77%) at a luminance of 6514 cd/m2 . This work provides an interesting idea to construct super high-efficiency PeLEDs by balancing the electron-hole recombination and enhancing the light outcoupling. This article is protected by copyright. All rights reserved.