Control of colour and charge injection in conjugated dendrimer/polypyridine bilayer leds

Conjugated dendrimers are an interesting class of materials for light emitting diodes, and can be used either as light-emitting or charge-transporting layers. We report a study of the use of a solution-processible dendrimer with distyrylbenzene core and stilbene dendrons. We find that its use in bilayer LEDs with polypyridine gives efficiencies ten times greater than for single layer polypyridine LEDs. The light emission can be either from the polypyridine or the dendrimer layer, depending on the layer thicknesses. This offers a way of tuning the colour of bilayer LEDs.