A thermally stable imidazole type ligand based Be complex as a triplet host material of green phosphorescent organic light emitting diodes

• Be based organometallic host material derived from imidazole based ligand.
• High quantum efficiency of 25.9% in green phosphorescent organic light-emitting diodes.
• High triplet energy of 2.73 eV and high glass transition temperature of 181 °C.

A 2-(4,5-dimethyl-1-phenyl-imidazol-2-yl)phenol ligand based Be complex, beryllium 2-(4,5-dimethyl-1-phenyl-imidazol-2-yl)phenolate (BePhIm), was investigated as a thermally stable host material of green phosphorescent organic light-emitting diodes (PHOLEDs). BePhIm was developed as a host material to have high triplet energy, thermal stability and balanced charge density. The triple energy of BePhIm was 2.73 eV and the glass transition temperature was 181 °C. Maximum quantum efficiency of the BePhIm based green PHOLEDs was 25.9%, which is better than any other quantum efficiency reported in green PHOLED using Be complexes as the host material.

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