Abstract: Iridium(III) complexes are among the most successful systems in the field of phosphorescent materials. Their metal–ligand molecular design strategy enables precise control over emission color, luminescence efficiency, and excited-state lifetime. This article begins with the challenge of low exciton utilization efficiency in organic light-emitting diodes (OLEDs), elucidates the underlying phosphorescence mechanism, and introduces the structures and synthetic routes of iridium(III) complexes, along with the ligand-mediated tuning of their emission colors. It further highlights recent research progress across various application domains, illustrating how rational ligand design imparts metal complexes with diverse functionalities and broad application potential.

Key words: Iridium (III) complexes, Phosphorescence, Ligand, Structural design, Emission color tuning, Applications