Blue light emitting diodes based on fluorescent CdSe∕ZnS nanocrystals

The authors report on the blue electroluminescence from CdSe∕ZnS core/shell nanocrystals prepared from ultrasmall, magic size CdSe clusters that have a diameter of less than 2nm. The light emitting device consists of an active layer of nanocrystals blended with 4,4′,N,N′- diphenylcarbazole and an evaporated electron transporting/hole blocking layer made of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline. A blue, stable electroluminescence at 485nm from the hybrid device was observed, in good agreement with the photoluminescence spectra of a solid film of the same nanocrystals used for the device.