Highly stable organic light emitting devices based on uniformly mixed hole transport layer

Abstract

High stable organic light emitting devices (OLEDs) can be achieved by using an Uniformly Mixed Hole transport layer (UM-HTL) composed of a mixture of 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) with N,N'-bis(1-naphthyl)-N,N'-diphenyl, 1,1'-biphenyl-4, 4'-diamine (NPB) in a 4:6 ratio of MADN:NPB. Compared to OLEDs using the conventional structure (t(90) = 1500 h) the lifetime of green tris(8-hydroxyquinoline) aluminum (Alq(3)) device using the UM-HTL can be improved to about 3 times (t(90) = 4420 h). Consequently utilizing the UM-HTL in OLEDs can effectively depress device degradation without impacting on the driving voltage and the color saturation significantly.