A novel electron transport material with triazole and diphenylphosphine oxide moieties for high efficiency OLEDs

A novel electron transport material with 1,2,4-triazole and diphenylphosphine oxide moieties (TPO) has been designed and synthesized. The material exhibits wide energy gap (3.77 eV), deep HOMO level (−6.28 eV), high triplet energy (2.86 eV), high glass transition temperature (133 °C) and high thermal stability (decomposition temperature at 423 °C). Device using TPO as electron transport material showed lower driving voltage and higher efficiency compared with the commonly used electron transport materials, such as 3,5-bis(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ), 1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene (TPBI) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP).