Effect of Phosphorescent Sensitizer on White Organic Light-Emitting Devices

We have fabricated high-etficiency 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-butyl-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 ( NP B ) 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 etficiency and luminance of the device with 3-wt.% Ir(ppy)3 and 2-wt.?JTB are 7.5cd A^-1 and 12020cd 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.