Phosphorescent Pt(II) Emitters for OLEDs: From Triarylboron-Functionalized Bidentate Complexes to Compounds with Macrocyclic Chelating Ligands.

The development of organic light-emitting diodes (OLEDs) has attracted enormous research efforts from both academia and industry in the past decades and tremendous progress has been made. However, the low operation lifetime of the blue phosphorescent OLEDs remains as one of the greatest bottlenecks limiting further applications of OLEDs. To address this problem, design and synthesis of triplet emitters with high phosphorescence quantum yield (ΦP ) and adequate thermal, chemical, electrical and ultraviolet (UV) stabilities are vital. This review summarizes the progress we made on the development of efficient and robust phosphorescent emitters based on cyclometalated Pt(II) compounds, particularly the ones with blue emission, starting from complexes with triarylboron-functionalized bidentate ligand to molecules incorporating tetradentate and macrocyclic ligands, with emphasis on their structure-property relationships.