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 Cu₄I₄ 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 cm², 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.