The effects of two spacers on white organic light-emitting diodes

The authors have demonstrated highly efficient white organic light-emitting diodes (WOLEDs) by using two emissive materials as a dopant, 1,4-Bis[2-(4'-diphenylaminobiphenyl-4-yl)vinyl]benzene (DABPV-ph) and iridium(III) bis(5-acetyl-2-phenylpyridinato-N,C2') acetylacetonate ((acppy)2Ir (acac)). In these WOLEDs, 2-methyl-9,10-di(2-naphthyl)anthracene (MADN), and 4,4'-N,N'-dicarbazole-biphenyl (CBP) were used as a spacer among the three emissive layers. The maximum luminous efficiency of the three devices with no spacer, MADN and CBP as a spacer were 11.50, 8.32, and 25.70 cd/A at 0.08, 12.7, and 0.01 mA/cm2 and the Commission Internationale De L'Eclairage (CIE(x, y)) coordinates were (x = 0.21, y = 0.34), (x = 0.21, y = 0.34), and (x = 0.33, y = 0.33) at 11 V, respectively.