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Compared with green and red perovskite light‐emitting diodes (PeLEDs), the development of blue PeLEDs has been lagging due to high defect density and inferior carrier transport. Herein, a novel defect‐passivation strategy is proposed to fabricate efficient sky‐blue PeLEDs by using isocyanate molecules. This strategy not only significantly reduces the nonradiative recombination loss caused by defects but also improves the injection and transport capacities of carriers by reducing the confinement effect. Benefiting from the passivation engineering and the reduction of confinement effect, the prepared sky‐blue PeLEDs present a significantly improved external quantum efficiency of 12.5% at 489 nm, which is 1.5 times higher than that of the control device. Meanwhile, the universality of isocyanate‐based passivators to improve the performance of PeLEDs is also demonstrated. The finding of this study provides a new reference for the selection of novel passivation agents to construct highly efficient blue PeLEDs. [ABSTRACT FROM AUTHOR]

Compared with highly efficient green, red, and near-infrared perovskite light-emitting diodes (PeLEDs), the performance of blue PeLEDs is still unsatisfactory due to the serious spectral instability issue at high working voltages. In this work, a multidentate amine-based ligand with four amino groups is utilized to achieve spectral stable blue quasi-2D PeLEDs. As a result, the optimized quasi-2D perovskite films exhibit stable photoluminescence spectra under continuous UV illumination and heating. Finally, the blue quasi-2D PeLEDs emitting at 478 nm with the peak external quantum efficiency up to 4.8% are achieved. Meanwhile, there is no obvious peak shift of the electroluminescence spectral under high external working voltages, exhibiting excellent spectral stability. The findings in this work confirm the validity of this strategy, providing a strategy to achieve steady blue PeLEDs. [ABSTRACT FROM AUTHOR]

Compared with red and green perovskite light‐emitting diodes (PeLEDs), blue PeLEDs are still unable to well control spectral stability due to the issues of ion migration and phase separation under external operating conditions. Herein, a strategy using organometallic ligands is reported to achieve spectrally stable PeLEDs. The obtained perovskite film exhibits stable photoluminescence spectra under UV excitation (365nm) and continuous heating of 70 °C. The device delivers an external quantum efficiency (EQE) of 6.7% with 50% lifetime (T50) of 21.6 min. Under high driving voltage (from 2 to 7.5 V), no obvious spectral shift has occurred for the electroluminescence spectrum at 481 nm. This work confirms the positive effect of organometallic ligands in quasi‐2D perovskite and provides a new idea for proposing effective ligands to act on the perovskite luminescence layer in the future. [ABSTRACT FROM AUTHOR]