P‐11.1: The interface engineering with quaternary ammonium ionic liquid enabling efficient blue perovskite light‐emitting diode

Metal halide perovskite light-emitting diodes (PeLEDs) have become a rising star in recent years. Interface plays an important role in the development of the PeLEDs performance. In this work, we demonstrate that the interface engineering with quaternary ammonium ionic liquid that could be used to improve the efficiency of the blue PeLEDs. We find the interface engineering can balance hole and electron injection. In addition, quaternary ammonium cation promotes the growth and nucleation of the blue perovskite emitter, improving its film morphology and reducing the occurrence of defects. The use of the ionic liquid interfacial layer is also helpful to inhibit the ion migration in the perovskite under forward bias operation. In conclusion, by exploring the quaternary ammonium ionic liquid interfacial layer, the luminous efficiency can be greatly improved.