Tunable red emission by incorporation of a rubrene derivative in p-type and n-type hosts in organic light emitting devices

A red-emitting rubrene derivative, 2-formyl-5,6,11,12-tetraphenylnaphthacene (2FRb) was separately doped into 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) and tris-(8-hydroxyquinoline) aluminum (Alq3) as the emitting layer. The emission can be tuned from 580 nm to 607 nm in NPB host and 560 nm to 622 nm in Alq3 host. The Alq3-hosted devices show better performances: more saturated pure red emission peaking at 622 nm with CIEx,y = [x = 0.65, y = 0.35], a maximum luminance efficiency of 2.42 cd/A and a maximum luminance of 3100 cd/m2 by doping 3.2 wt.% 2FRb in Alq3 host. It indicates that the derivative of rubrene is a promising bipolar dopant for red light-emitting device.