Phosphorescent organic light emitting diode efficiency enhancement using functionalized silver nanoparticles

摘要

Silica coated silver nanoparticles (NPs) were incorporated into the emissive layer of a phosphorescent organic light emitting diode (PHOLED). As a result, the luminescence efficiency of the PHOLED was significantly improved under low charge carrier injection level. The silver NPs facilitate the exciton formation event and are responsible for the PHOLED performance improvement. In contrast, the incorporation of uncoated bare silver NPs greatly suppresses luminescence of the PHOLED due to metal NPs induced luminescence and exciton quenching. The silica shell coated on Ag NPs surface plays a dual role in enhancing the PHOLED luminescence efficiency: as an optical spacer, it avoids luminescence quenching of the dye caused by Ag NPs; as an insulator, it prevents exciton recombination at the Ag NPs surface. Therefore, a silica shell with thickness 13 nm or above is essential to enhance the PHOLED performance.