A diaminomaleonitrile derivative as a new dopant for red-light-emitting electroluminescent device

Abstract

We have synthesized a novel dye material of N,N′-bis[4-(N,N′-diphenylamino)-benzalidene] diaminomaleonitrile (BAP), as a dopant for red-light-emitting electroluminescent (EL) device. We fabricated several types of EL devices by doping BAP into tris(8-quinoline) aluminium (Alq3) as the light-emitting layer, and investigated their EL properties. BAP has symmetric conjugated structure and could give sharp and intense photoluminescence in the red region. When BAP was doped into Alq3, the device gave bright red EL with the maximum intensity of about 6700 cd m−2 together with the contribution of Alq3 emission. By introducing rubrene as an assist-dopant, the maximum EL intensity increased to 15 700 cd m−2 when the bias voltage was 14.5 V. However, complete energy transfer to BAP has not been achieved.