A new yellow fluorescent dopant for high-efficiency organic light-emitting devices

We describe the design and synthesis of a sterically hindered yellow dopant, tetra(t-butyl)rubrene (TBRb) which, when doped in either 1,4-bis[N-(1-naphthyl)-N′-phenylamino]-biphenyl or aluminum tris(8-hydroxyquinoline) (Alq3) as emitter, shows nearly 25% increase in luminance efficiency over that of the state-of-the-art rubrene (Rb) device without significantly effecting its corresponding color. At 5% doping in Alq3 and 20 mA/cm2 current drive condition, the electroluminescence efficiency of TBRb reaches 8.5 cd/A and 2.8 lm/W with a yellow color of Commission Internationale de l'Eclairage chromaticity coordinates (CIEx,y) = [0.52, 0.48], which is among the best ever reported for yellow electrofluorescence in organic light-emitting devices.