Production of C, N Alternating 2D Materials Using Covalent Modification and Their Electroluminescence Performance

Carbon nitrides (C 3 N 4 ) show excellent properties in various optical and optoelectronic applications. However, their application to electroluminescence (EL) devices is limited by the lack of production methods of homogeneous dispersions in organic solvents, which are critically required for device fabrication. Herein, a strategy to generate stable dispersions of fluorescent, 2D C 3 N 4 materials, and demonstrate light‐emitting diodes (LEDs) based on them is proposed. The treatment of urea‐driven C 3 N 4 (UCN) with methoxy‐benzene diazonium salt (MD) produces dispersions in organic solvents. Experimental and theoretical studies suggest that MD treatment passivates the surface defects of the UCN. The resulting LED devices show bright green luminescence with an external quantum efficiency of 0.91%. This unprecedented result opens an era of C 3 N 4 emitters as future promising light emitters in displays and solid‐state lighting.