High Performance Solution‐Processed Deep‐Blue Phosphorescence Organic Light‐Emitting Diodes with EQE Over 24% by Employing New Carbenic Ir(III) Complexes

Abstract Solution‐processed phosphorescence organic light‐emitting diodes (PHOLEDs) are an increasingly attractive option as compared with vacuum‐processed PHOLEDs due to their lower costs, large areas, and flexible production. Currently, the majority of reported solution‐processed PHOLEDs are produced using red and green triplet emitters. The earlier reports on blue solution‐processed PHOLEDs describe poor Commission International de l'Éclairage color coordinates (CIE( x , y )) and low external quantum efficiencies (EQEs). It is difficult to produce efficient solution‐processed deep‐blue PHOLEDs that meet high EQE and CIE y color coordinate ≤ 0.15 requirements. The authors design and synthesize three new carbenic homoleptic deep‐blue emitting Ir(III) complexes for solution‐processed PHOLEDs. The introduction of bulky tert ‐butyl and trifluoromethyl (CF 3 ) substituents at a suitable position on the benzylated pyridoimidazole moiety effectively improves solution‐processed device performance without compromising CIE( x , y ) color purity. The deep‐blue PHOLEDs exhibit remarkable maximum EQE (EQE max ) of 25.3% and excellent CIE( x , y ) color of (0.16, 0.10) at a mer ‐Ir(ptbbp) 3 doping ratio of 50 wt%. In particular, deep‐blue PHOLEDs containing mer ‐Ir(CF 3 pbp) 3 as dopant exhibit excellent CIE( x , y ) color coordinates of (0.16, 0.05) and an EQE max of 21.2%. This is the first report of deep‐blue solution‐processed PHOLEDs containing carbene‐based Ir(III) complexes with extremely high EQE values and CIE y coordinate requirement.