Bipyridyl substituted triazoles as hole-blocking and electron-transporting materials for organic light-emitting devices

Abstract

We have demonstrated bipyridyl substituted triazole derivatives (Bpy-TAZs) as an electron-transporting material for organic light-emitting devices (OLEDs). Substitution of triazole with bipyridyl is a good way to improve electron-transporting ability of triazoles with keeping good hole-blocking ability, which is a useful property of triazole derivatives. A Bpy-TAZ has high electron mobility of above 10−4cm2/Vs. Moreover, by employing one of Bpy-TAZs as a hole-blocking and electron-transporting material for phosphorescent OLEDs, lower operation voltage was achieved with keeping the same external quantum efficiency of electroluminescence (almost 10%) as compared with the conventional hole-blocking and electron-transporting bilayer consisting of bathocuproine and tris (8-hydroxyquinolinato) aluminum.