Coordination Compensation Stabilization of Monodentate‐Ligand Copper‐Iodide Hybrids for Efficient Light‐Emitting Diodes With Record‐High External Quantum Efficiency Above 20%

ABSTRACT Copper–iodide hybrids have emerged as promising candidates for eco‐friendly light‐emitting diodes (LEDs). Although high‐efficiency LEDs based on multidentate‐ligand copper–iodide hybrids have been reported, those utilizing monodentate‐ligand ones remain challenges because their surface ligands are prone to dissociation, producing exposed Cu + ions that induce non‐radiative recombination. Herein, we propose a coordination compensation stabilization strategy to achieve efficient monodentate‐ligand copper–iodide LEDs by incorporating pyridine‐terminated semiconducting molecules. We demonstrate that the strong electron‐withdrawing moieties of pyridine are integrated to stabilize Cu 4 I 4 core by increasing the electron cloud density of termini contacting with cluster, which enhances the coordination with exposed Cu + ions. This strategy synergistically passivates the ionized metallic defects to reduce non‐radiative recombination and increases the carrier mobility to promote electron/hole transport within emitters. Consequently, we fabricate LEDs reaching a record‐high electroluminescence efficiency of 20.4% with an average of 19.8% over 60 devices, half‐lifetime of 1117.5 h, large‐area of 81 cm 2 , and demonstrate a broad universality applicable to various monodentate‐ligand hybrids, representing a sufficiently striking advance over existing copper‐iodide systems. The study provides a new strategy to pave the way for enhanced device performance of copper–iodide hybrid LEDs toward practical applications.