Polypyridine as an efficient electron-transporting polymer for light-emitting diodes

In polymer light-emitting diodes (LEDs), a pre-requisite for efficient operation is the balance of injection and transport of electrons and holes. This has stimulated much research into suitable electron-injecting and transporting materials. We report the use of polypyridine as an efficient electron-transporting layer in polymer LEDs. We have achieved much improved LED performance by incorporating polypyridine as an electron-transporting polymer in LEDs using either poly(p-phenylenevinylene) or poly(2-methoxy, 5-(2'ethyl-hexyloxy)-p-phenylenevinylene as the hole-transporting and emitting layer. The optimisation of the layer thicknesses leads to increases in efficiency of up to a factor 60 over comparable single layer devices.