A host material consisting of phosphinic amide for efficient sky-blue phosphorescent organic light-emitting diodes

• A NPO linkage is constructed to obtain high triplet energy.
• A NPO linkage serves as a bipolar core for host material.
• A bicarbazole backbone gives good hole transportability to host material.
• A blue PHOLED device based on PBCz-PO host exhibited a maximum EQE of 13.4%.

A new bipolar host material (PBCz-PO) consisting a phosphinic amide is developed to show a resonance effect. It possesses quite high triplet energy (2.76 eV), and this high triplet energy make it suitable to be blue host in phosphorescent organic light-emitting diodes (PHOLEDs). The device with PBCz-PO as a host and FIrpic as a dopant achieved a maximum current efficiency (ηc) of 31.5 cd/A, a maximum power efficiency (ηp) of 31.0 lm/W and a maximum external quantum efficiency (EQE) of 13.4% as well as low driving voltage.

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