Blue light emitting semiconductor nanocrystals and devices

Abstract

A blue light emitting semiconductor nanocrystal having an quantum yield of greater than 20% can be incorporated in a light emitting device.

1 . A semiconductor nanocrystal comprising a core including cadmium, zinc, and sulfur. 
     
     
         2 .- 17 . (canceled) 
     
     
         18 . The nanocrystal of  claim 1 , wherein the core includes ZnCdS. 
     
     
         19 . The nanocrystal of  claim 1 , further comprising an overcoating on the core, the overcoating including a second semiconductor material. 
     
     
         20 . The nanocrystal of  claim 19 , wherein the second semiconductor material includes ZnS. 
     
     
         21 . The nanocrystal of  claim 1 , wherein the nanocrystal when excited emits blue light. 
     
     
         22 . The nanocrystal of  claim 1 , wherein the nanocrystal when excited emits blue light with a quantum efficiency of at least 20%. 
     
     
         23 . The nanocrystal of  claim 1 , wherein the nanocrystal when excited emits blue light with a quantum efficiency of at least 40%. 
     
     
         24 . The nanocrystal of  claim 23 , wherein the blue light has a peak wavelength shorter than 470 nm. 
     
     
         25 . A light emitting device comprising:
 a first electrode;   a second electrode; and   a semiconductor nanocrystal comprising a core including cadmium, zinc, and sulfur disposed between the first electrode and the second electrode.   
     
     
         26 . The light emitting device of  claim 25 , further comprising a first charge transporting layer including a first inorganic material in contact with a first electrode arranged to introduce charge in the first charge transporting layer. 
     
     
         27 . The light emitting device of  claim 25 , further comprising a second charge transporting layer in contact with the second electrode, wherein the second electrode is arranged to introduce charge in the second charge transporting layer. 
     
     
         28 . The light emitting device of  claim 25 , wherein the first charge transporting layer is a hole transporting layer. 
     
     
         29 . The light emitting device of  claim 27 , wherein the second charge transporting layer is an electron transporting layer. 
     
     
         30 . The light emitting device of  claim 25 , wherein the semiconductor nanocrystal is a member of a plurality of semiconductor nanocrystals forming a monolayer.