Strategies for Stability Enhancement of Metal Halide Perovskite Nanocrystals for Efficient and Stable Perovskite LEDs

Metal halide perovskite nanocrystals (PeNCs) exhibit narrow emission spectral linewidths, high color purity, and low-temperature solution processability, making them promising emitters for next-generation light-emitting diodes (LEDs). However, their practical application remains limited by the ionic nature of the PeNC surface, which leads to ligand desorption, defect formation, and structural degradation under ambient air exposure and device operation. This review focuses on three material design strategies of ligand engineering, encapsulation, and crosslinking to overcome this intrinsic instability of PeNCs. Ligand engineering employs aliphatic ionic, metal-coordinated Z-type, and aromatic conjugated ligands to strengthen the surface binding and passivate point defects at the molecular level. Encapsulation provides physical barriers against moisture, oxygen, and thermal stress using inorganic shells (SiO2, ZrO2, ZnS, and CdS) or polymer matrices. Crosslinking chemically links adjacent nanocrystals or ligand chains, forming insoluble networks that reduce ligand desorption, solvent damage, and ion migration. We reviewed how these strategies affect the photoluminescence (PL) retention and colloidal stability of PeNCs, charge transport, and operational stability in perovskite light-emitting diodes (PeLEDs). Based on this review, we summarize the material design principles for developing highly stable PeNC-based LEDs.