Effect of coupling between excitons and gold nanoparticle surface plasmons on emission behavior of phosphorescent organic light-emitting diodes

Enhanced efficiency and reduced efficiency roll-off in phosphorescent organic light-emitting diodes (PhOLEDs) are realized by interposing a solution-processed gold nanoparticle (GNP)-based interlayer between the anode and the hole-injection layer. Transient photoluminescence measurements elucidate that a reduced lifetime of the triplet excitons was observed for samples having a GNP-interlayer as compared to a control sample without the GNP-interlayer. The decrease in the triplet exciton lifetime, caused by the coupling between the triplet excitons and the localized surface plasmons (LSPs) excited by the GNPs, enables reducing the triplet-triplet and triplet-polaron annihilation processes, thereby a reduced efficiency roll-off in PhOLEDs. The presence of a GNP-interlayer also acts as an optical out-coupling layer contributing to the efficiency enhancement and was demonstrated by the theoretical simulation. (C) 2015 Elsevier B.V. All rights reserved.