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

Abstract

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 0.3 nm. With another 32-nm-thick ZnS film as a refractive index-matching layer onto the optimized Al (0.3 nm)/Ag (18 nm) electrode, the maximum luminance and efficiency for the TEOLED based on Alq3 emission reach 145 474 cd/m2 (13 V) and 12.2 cd/A (5 V), respectively. © 2006 American Institute of Physics.