Electroluminescence from europium(III) complexes

• Recent development of electroluminescent europium(III) complexes is reviewed.
• Design principle of optoelectronic europium(III) complexes is introduced.
• Ligand functionalization is highlighted to embody structure–property relationships.

Lanthanide complexes are widely used as emitters for applications in the fields of bioimaging, molecular sensing, disease diagnosis, and optoelectronics. Particularly, the high luminescence efficiencies of these complexes make them attractive for electroluminescent display and solid-state lighting. As color purity and saturation are the most stringent criteria for red emission in display technology, europium(III) complexes featuring an emission peak centered at ∼612 nm with a narrow bandwidth hold great potential as red-emitting materials. This review highlights the recent development of electroluminescent europium(III) complexes, with emphasis on correlations between molecular structures and optoelectronic performance. After a fundamental introduction on the optical and electrical properties of europium(III) complexes, efforts will be devoted toward the controlled synthesis and functionalization of molecules for improved charge injection/transportation, good processability, and enhanced emission efficiency.