One-shot triphenylamine/phenylketone hybrid as a bipolar host material for efficient red phosphorescent organic light-emitting diodes

Abstract

Abstract A new bipolar host material, 2,2′,2′′-tris(diphenylketone)amine (N-DPK) was developed in a one-shot by Ullmann reaction, and characterized by spectroscopic techniques and spatial arrangement was ascertained by single X-ray crystal structure analysis. The compound is possessing C3-symmetry with three diphenylketone units connected to the central nitrogen atom. In this organic architecture, the electron-withdrawing units, phenylketone are incorporated to ortho-position of triphenylamine, electron-donating unit to generate rigidity, which is responsible to reduce the gap between single and triplet energy levels. The material possessed triplet energy (ET) at 2.53 eV, indicating that it could be used as a host material for red phosphorescent organic light-emitting diodes. The OLED device was fabricated with bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)iridium(III) (Ir(MDQ)2acac) and N-DPK, as guest and host, respectively, and 10 wt% doping concentration exhibited good device performance with maximum external quantum efficiency (EQE) of 16.1%.