Strong Luminescent Iridium Complexes with CˆN=N Structure in Ligands and Their Potential in Efficient and Thermally Stable Phosphorescent OLEDs

Homoleptic iridium complexes with CˆN=N type ligands, i.e., 1,4-bis (phenyl) phthalazine (BPPa) and 3,6-bis(phenyl)pyridazine (BPPya), are strong phosphorescents, easy to synthesize, and thermally stable, thus having great potential in optical electronic applications, as demonstrated in Ir(BPPa)3-based OLED devices. A quantum chemistry study shows that CˆN=;N type ligands can bond to Ir more strongly.