A novel family of boron-containing hole-blocking amorphous molecular materials for blue- and blue-violet-emitting organic electroluminescent devices

A novel family of amorphous molecular materials that function as hole blockers in organic electroluminescent (EL) devices, tris(2,3,5,6-tetramethylphenyl)borane (TPhB), tris(2,3,5,6-tetramethylbiphenyl-4-yl)borane (TBPhB), tris(2,3,5,6-tetramethyl-1,1';4',1"-terphenyl-4-yl)borane (TTPhB), and tris[4-(1,1';3',1"-terphenyl-5'-yl)-2,3,5,6-tetramethylphenyl]borane (TTPhPhB), have been designed and synthesized. They readily from stable amorphous glasses with high glass-transition temperatures, and are characterized by reversible cathodic reduction and relatively large HOMO-LUMO energy gaps. High-performance blue- and blue-violet-emitting organic EL devices have been developed using TBPhB, TTPhB, and TTPhPhB as hole blockers and N,N'-di(1-naphthyl)-N,N'-diphenyl[1,1'-biphenyl]-4,4'-diamine, tri(p-terphenyl-4-yl)amine, and N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine as emitters.