Electroluminescent Property of a Beryllium Metal-chelate Complex Used as the Electron-transporting Host Material

Abstract

A simple and highly efficient single-emitting-layer phosphorescent organic light-emitting diode (PHOLED) that used bis[2-(2-hydroxyphenyl)-4-methyl-pyridine] beryllium(Bempp) as the electron-transporting host material and bis (pyridylphenyl) iridium (III) (N, N'-diisopropyl-benzamidine) (PPP) as the phosphorescent dye to enhance the electro-luminescence (EL) performance was presented. This PHOLED device exhibited substantially lower driving voltage(2.5 V) and higher EL efficiencies than those based on the CBP host. It showed dramatically enhanced peak values of more than 63.1 cd/A for luminous efficiency, 54.0 lm/W for power efficiency. The high EL performance was attributed to the well-matched energy levels of Bempp with the hole/electron-transporting (HT/ET) materials as well as the highly efficient and complete energy transfer between the host and the guest. The results demonstrate that Bempp is a promising host material to replace the commonly used CBP because of its higher EL efficiency and its relative high triplet energy (ca. 2.6 eV).