Highly efficient blue organic light emitting diodes using various hole and elect

In this Letter, blue phosphorescence organic light-emitting diodes (PHOLEDs) employ structures for electron and/or hole confinement; 1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene is used as a hole confinement layer and tris-(phenylpyrazole)iridium [Ir(ppz)3] is utilized for an electron confinement la