Effect of Phosphorescent Sensitizer on White Organic Light-Emitting Devices

Abstract

We have fabricated high-efficiency white organic light-emitting devices by using the phosphorescent material factris (2-phenylpyridine) iridium [Ir(ppy3)] as a sensitizer. Ir(ppy)3 and the fluorescent dye 4-(dicyanomethylene)-2-t-buty1-6-(1,1,7,7-tetramethyljulolidyl-9-enyl) (DCJTB) are co-doped into 4,4′-N,N′ -dicarbazole-biphenyl (CBP) host. N,N′ -diphenyl-N,N′ -bis(1-naphthyl)-(1,1′ -biphenyl)-4,4′ -diamine (NPB) acts as a blue light-emitting as well as hole-transporting layer. The chromaticity of white emission can be tuned by adjusting the concentration of Ir(ppy)3 and DCJTB. The maximum efficiency and luminance of the device with 3-wt.% Ir(ppy)3 and 2-wt.% DCJTB are 7.5cd A-1 and 12020 cd m-2, respectively, which produces fairly pure white emission with the commission international De L'Eclairage coordinates of (0.33,0.32) at 10 V.