Operational Stability Issues and Challenges in Metal Halide Perovskite Light-Emitting Diodes.

Metal halide perovskite light-emitting diodes (Pe-LEDs) have shown promise for high-definition displays because of their wide color gamut (∼140%) and narrow emission band. Although the external quantum efficiency (EQE) of Pe-LEDs increased rapidly from ∼1% to more than 20% in several years, they still suffer from poor operational stability, which has been recognized as the bottleneck for commercial application of Pe-LEDs. Although the environmental sensitivity of perovskites can be avoided by encapsulation approaches, the ion migration of perovskites is easily induced by crystal defects under the action of an electric field in the operating state, thus accelerating irreversible phase transition and physical degradation of the perovskites. Additionally, the unbalanced carrier injection of Pe-LEDs could induce great Auger recombination and Joule heating, which deteriorate the operational stability of devices. Considering these issues, coping strategies, such as surface engineering, ion doping, and quantum confinement control of perovskites and structure design and thermal management of devices, are discussed in this Perspective.