For example, we demonstrated the fabrication of multilayer polymer LEDs with white emission, high efficiency and good color stablility (Multiolayer Polymer Light Emitting Diodes: White-Light Emission with High Efficiency, Gong, X.; Wang, S.; Moses, D; Bazan, G.C.; Heger, A.J. Adv. Mat. 2005, 17, 2053-2057). Such devices have the potential to be more efficient than coventional light sources and may provide substantial energy savings. The choice of materials includ a sulfonated electron transport oligomer, a blend containung a blue emitting poly(fluorene) with elctron transport end groups and an anionic version of poly(vinylcarbazole) forthe hole injections layer.