Reduced Confinement Effect by Isocyanate Passivation for Efficient Sky‐Blue Perovskite Light‐Emitting Diodes

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. An isocyanate molecule, 2,4‐toluene diisocyanate (2,4‐TDI), is introduced into perovskite to fabricate sky‐blue perovskite light‐emitting diodes (PeLEDs). Benefiting from the passivation engineering and reduced confinement effect by 2,4‐TDI molecules, an efficient sky‐blue PeLED at 489 nm with a significantly improved external quantum efficiency of 12.5%, which is 1.5 times that of the control device is successfully fabricated.