A Novel Family of Boron‐Containing Hole‐Blocking Amorphous Molecular Materials for Blue‐ and Blue–Violet‐Emitting Organic Electroluminescent Devices

Abstract 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 form 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.