Abstract
Perovskite quantum-dot-based light-emitting diodes (QLEDs) possess the features of wide gamut and real color expression, which have been considered as candidates for high-quality lightings and displays. However, massive defects are prone to be reproduced during the quantum dot (QD) film assembly, which would sorely affect carrier injection, transportation and recombination, and finally degrade QLED performances. Here, we propose a bilateral passivation strategy through passivating both top and bottom interfaces of QD film with organic molecules, which has drastically enhanced the efficiency and stability of perovskite QLEDs. Various molecules were applied, and comparison experiments were conducted to verify the necessity of passivation on both interfaces. Eventually, the passivated device achieves a maximum external quantum efficiency (EQE) of 18.7% and current efficiency of 75 cd A−1. Moreover, the operational lifetime of QLEDs is enhanced by 20-fold, reaching 15.8 h. These findings highlight the importance of interface passivation for efficient and stable QD-based optoelectronic devices.
Highlights
Perovskite quantum-dot-based light-emitting diodes (QLEDs) possess the features of wide gamut and real color expression, which have been considered as candidates for high-quality lightings and displays
In summary, the bilateral passivation strategy demonstrated in this work results in effectively controlling the surface states of quantum dot (QD) films
We introduced a layer of organic molecules (e.g. P = O, S = O and C = O) on both top- and bottom-side interface of QD films to reduce the defect density and suppressed the nonradiative recombination
Summary
Perovskite quantum-dot-based light-emitting diodes (QLEDs) possess the features of wide gamut and real color expression, which have been considered as candidates for high-quality lightings and displays. The operational lifetime of QLEDs is enhanced by 20-fold, reaching 15.8 h These findings highlight the importance of interface passivation for efficient and stable QD-based optoelectronic devices. LEDs have achieved 20.3% and 21.6% of EQE at green and infrared region, respectively[7,8] The maximum EQE of blue and green QLEDs is 2.8%14 and 16.48%15, respectively, which is lower than that of film-based perovskite LEDs16,17. Massive hanging bonds or defects[23,24] on QDs would reduce exciton recombination efficiency In this regard, some surface passivation routes were applied, such as introducing the organic ligand of didodecyl dimethyl ammonium bromide (DDAB)[25,26], or passivating the QDs with inorganic ligands[27,28]. It is crucial to improve device performance from the perspective of QD films
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