High quantum efficiency in blue phosphorescent organic light emitting diodes using ortho-substituted high triplet energy host materials

•Carbazole modified terphenyl based high triplet energy host material.•High quantum efficiency in blue phosphorescent organic light-emitting diodes.•Ortho linked terphenyl core structure for host material.

A high triplet energy material derived from carbazole and ortho terphenyl, 3,3′′-di(9H-carbazole-9-yl)-1,1′:2′,1′′-terphenyl (33DCTP), was synthesized as the host material for blue phosphorescent organic light-emitting diodes (PHOLEDs). The 33DCTP host showed high glass transition temperature of 110 °C, high triplet energy of 2.77 eV, the highest occupied molecular orbital of −6.12 eV and the lowest unoccupied molecular orbital of −2.52 eV. High efficiency blue PHOLEDs were developed using the 33DCTP host and bis((3,5-difluorophenyl)pyridine) iridium picolinate dopant material, and high quantum efficiency of 23.7% was achieved with a color coordinate of (0.14, 0.28).

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