Pure green and narrow bandwidth electroluminescence from organic light-emitting diodes

Pure green and narrow bandwidth emission from organic bilayer electroluminescent devices were presented by using Tb3+ : (SA)(3) as hole-transporting layer and emissive layer, and high fluorescent material Alq(3) acting as electron-transporting layer. It proves that the emission comes from carriers' recombination after their tunneling through the inner interface (Tb3+ :(SA)(3)/Alq(3)) in the bilayer ITO/Tb3+ :(SA)(3)(40nm)/Alq(3) (55 nm)/Al diode. The spectrum of the bilayer devices varies with the thickness of the electron-transporting layer. Keeping the thickness of Tb3+ :(SA)(3) layer constant, there is no emission from Alg layer when Ale layer reduces to 12 nm; meanwhile, pure green and narrow bandwidth emission can be observed. Thus, it provides a simple way to obtain high luminance and long-term stability by reducing electron- or hole-transporting layer, especially, by using a lanthanide complex for emissive layer.