Undoped, red organic light-emitting diodes based on a N,N,N’,N’-tetraphenylbenzidine (TPD) derivative as red emitter with a triphenylamine derivative as hole-transporting layer

A novel dicyanovinyl-functionalized N,N,N’,N’-tetraphenylbenzidine (TPD) derivative, N,N’-bis[4-(1,1-dicyanovinyl)phenyl]-N,N’-bis(4-fluorophenyl)benzidine and a novel triphenylamine-based derivative, 4,4′,4″-tris{[di(p-tolyl)amino]phenyl}triphenylamine were synthesized and employed as red molecular emitter and hole-transporting layer, respectively, in an undoped organic light-emitting diode devices. The device based on the TPD-FCN emitter and DBTPA hole-transporting material, which was fabricated in a facile non-doped configuration, achieved maximum luminance of 3400 cd m−2 at a driven voltage of 17.5 V and maximum luminous efficiency of 3.04 cd A−1. Interestingly, the device reached a brightness of 1399 cd m−2 and luminous efficiency of 2.85 cd A−1 at the low current density of 20 mA cm−2.