Pyridoindole based intramolecular charge transfer type host material for blue phosphorescent organic light-emitting diodes

• Carbazole and pyridoindole based host materials for blue phosphorescent organic light-emitting diodes.
• Improved electron transport by heteroatomic pyridoindole moiety.
• Triplet energy keeping function of diphenylether linking unit.

A meta-linked diphenylether based host material, 9-(3-(3-(9H-carbazol-9-yl)phenoxy)phenyl)-9H-pyrido[2,3-b]indole (CzDPEPI), was investigated as an intramolecular charge transfer type host material to harvest triplet excitons of phenylimidazole type blue Ir triplet emitters. A host with two carbazole units was a reference material to confirm the role of the pyridoindole moiety. The CzDPEPI host behaved as a high triplet energy and driving voltage reducing host due to the pyridoindole moiety assisting electron injection and improved power efficiency of blue phosphorescent device.