Bright white small molecular organic light-emitting devices based on a red-emitting guest-host layer and blue-emitting 4,4′-bis(2, 2′-diphenylvinyl)-1,1′-biphenyl

Abstract

Bright multilayer white organic light-emitting devices (OLEDs) based on red-emitting [2-methyl-6-[2-∼(2,3,6,7-tetrahydro-1H, 5H-benzo [ij] quinolizin-9-yl)-ethenyl]-4H-pyran4-ylidene] propane-dinitrile (DCM2)-doped N,N′-diphenyl-N,N′-bis(1-naphthylphenyl)-1, 1′-biphenyl-4,4′-diamine (α-NPD) and blue-emitting 4,4′-bis(2,2′-diphenylvinyl)-1, 1′-biphenyl (DPVBi) are described. The blue emission increased relative to the red emission with increasing bias, but the color coordinates of the total emission were well within the white region at V>10V. The most lightly doped device, which contained a 5 nm thick layer of 0.5 wt. % of the dye dopant, exhibited the highest power efficiency, 4.1lm/W, external quantum efficiency of 3.0%, and white brightness Lmax>50000Cd/m 2 (at ∼1100 mA/cm2). © 2002 American Institute of Physics.