Recent Advances in Ligand Engineering for Stable Halide Perovskite Light-Emitting Diodes

Lead halide perovskites have significant potential as promising materials for a wide range of optoelectronic applications, including solar cells, light-emitting diodes, and photodetectors, due to their outstanding optical and electrical properties. Despite these remarkable properties, their intrinsic structural and environmental instability remains a major barrier to commercialization, as they are highly susceptible to degradation under heat, light, moisture, and bias. To address these challenges, extensive efforts have been devoted to improving the stability of perovskite materials through ligand engineering. In particular, diverse organic ligands with carefully tailored molecular structures have been developed to passivate surface defects and enhance structural robustness. This review highlights recent progress in ligand engineering strategies, focusing on how the structural design of ligands, specifically the number of functional groups within each ligand and the number of ligands coordinating with the perovskite surface, can effectively suppress degradation pathways and improve device performance. Based on these criteria, ligands are categorized into monodentate, polydentate, and dual-ligand systems. This classification provides a framework for systematically exploring ligand–perovskite interactions, ultimately contributing to the realization of durable, efficient, and commercially viable perovskite-based optoelectronic devices.

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