Realizing both improved luminance and stability in organic light-emitting devices based on a solution-processed inter-layer composed of MoO_X and Au nanoparticles mixture

We report on the solution-processed mixture of Au nanoparticles (NPs) and MoO_X as an inter-layer in organic light-emitting devices (OLEDs), leading to the enhanced light emission and good stability. An impressive enhancement in current efficiency and power efficiency is achieved up to 70% and 100%, respectively. A systematic study to the effect of the Au NPs:MoO _X inter-layer on OLEDs demonstrates that the improved electrical properties is mainly ascribed to the enhanced hole injection due to the high work function of MoO_X and the good conductivity of Au NPs, and the enhanced optical properties is mainly attributed to the localized surface plasmon induced by Au NPs, which makes a great contribution to the improved efficiency. Besides, Au NPs:MoO_X inter-layer also behaves superior to the frequently-used polyethylene dioxythiophene:polystyrene sulfonate (PEDOT:PSS) in device stability. The decay ratio for Au NPs:MoO_X based device is 60% after 80 h, while it is nearly dying out for the device with PEDOT:PSS inter-layer.