Communication: Balanced charge injection and mobility are required for efficient electroluminescence (EL) in light-emitting diodes (LEDs). Here a novel approach towards this end is described-the direct attachment of the electron transporting material 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD) to the backbone of poly(p-phenylenevinylene) (PPV). The fabrication and performance efficiency of devices based on this polymer are reported. It is found that the EL efficiency is improved to a remarkable extent, which is ascribed to a more facile electron injection and an enhancement of the electron transporting properties of the polymer.