Improved light outcoupling for top-emitting organic light-emitting devices

Light outcoupling for the top-emitting organic light-emitting device (TEOLED) with the structure of Si∕SiO2∕Ag∕Ag2O∕4,4′, 4″-tris(3-methylphenylphenylamino)triphenylamine/4, 4′-bis[N-(1-naphthyl-1-)-N-phenyl-amino]-biphenyl/tris-(8-hydroxyquinoline) aluminum (Alq3)∕LiF∕Al∕Ag is improved by optimizing the semitransparent Al∕Ag cathode and employing a ZnS top-capping layer. To both provide a fine electron injection and reduce Al absorption in the visible area, Al thickness is adjusted to 0.3nm. With another 32-nm-thick ZnS film as a refractive index-matching layer onto the optimized Al (0.3nm)∕Ag (18nm) electrode, the maximum luminance and efficiency for the TEOLED based on Alq3 emission reach 145474cd∕m2 (13V) and 12.2cd∕A (5V), respectively.