AN EFFICIENT ELECTRON-TRANSPORTING POLYMER FOR LIGHT-EMITTING-DIODES

The efficient operation of polymer light-emitting diodes (LEDs) requir es balanced injection and transport of electrons and holes. This has s timulated much research into suitable electron-injecting and transport ing materials. We report the use of polypyridine as an efficient elect ron-transporting polymer. We have achieved much-improved LED performan ce by incorporating polypyridine as an electron-transporting layer in a poly(p-phenylene vinylene) (PPV) LED and optimizing layer thicknesse s to balance transport of electrons and holes. The external quantum ef ficiency of these LEDs is 0.25%, 60 times greater than similar devices without the electron-transporting layer.