Alloyed semiconductor nanocrystals

Abstract

The invention relates to methods for preparing 3-element semiconductor nanocrystals of the formula WYxZ(1-x), wherein W is a Group II element, Y and Z are different Group VI elements, and 0<X<1, comprising dissolving a Group II element, a first Group VI element, and a second Group VI element in a one or more solvents. The Group II, VI and VI elements are combined to provide a II:VI:VI SCN precursor solution, which is heated to a temperature sufficient to produce semiconductor nanocrystals of the formula WYxZ(1-x). The solvent used to dissolve the Group II element comprises octadecene and a fatty acid. The solvent used to dissolve the Group VI elements comprises octadecene. The invention also includes semiconductor nanocrystals prepared according to the disclosed methods, as well as methods of using the semiconductor nanocrystals.

1 . A plurality of semiconductor nanocrystals, wherein,
 each of the semiconductor nanocrystals comprises an alloyed semiconductor core comprising a semiconductor having the formula CdSxSe(1-x), wherein x is from 0.15 to 0.84; and   the plurality of semiconductor nanocrystals emit radiation in a wavelength range from 665 nm to 490 nm with a full-width-half-maximum emission from 27 nm to 40 nm for a corresponding molar ratio of S to Se from 0.18 to 5.25 when illuminated with an ultraviolet light source.   
     
     
         2 . The plurality of semiconductor nanocrystals of  claim 1 , wherein the full-width-half-maximum emission is from 30 nm to 35 nm. 
     
     
         3 . The plurality of semiconductor nanocrystals of  claim 1 , wherein the plurality of semiconductor nanocrystals has a quantum yield of at least 15%. 
     
     
         4 . The plurality of semiconductor nanocrystals of  claim 1 , wherein the plurality of semiconductor nanocrystals has a quantum yield of from 30% to 60%. 
     
     
         5 . The plurality of semiconductor nanocrystals of  claim 1 , wherein each of the semiconductor nanocrystals has a size up to 6 nm. 
     
     
         6 . The plurality of semiconductor nanocrystals of  claim 5 , wherein each of the semiconductor nanocrystals has a size within 7% of the average size of the plurality of semiconductor nanocrystals. 
     
     
         7 . The plurality of semiconductor nanocrystals of  claim 1 , wherein each of the semiconductor nanocrystals retains a fluorescence intensity that is within 20% of the original fluorescence intensity after 10 minutes following excitation with a UV light source. 
     
     
         8 . The plurality of semiconductor nanocrystals of  claim 1 , wherein each of the semiconductor nanocrystals comprises a semiconductor shell. 
     
     
         9 . The plurality of semiconductor nanocrystals of  claim 8 , wherein the semiconductor shell comprises ZnS, CdS, CdSe, CdTe, GaAs, or AlGaAs. 
     
     
         10 . The plurality of semiconductor nanocrystals of  claim 8 , wherein the semiconductor shell comprises ZnS. 
     
     
         11 . The plurality of semiconductor nanocrystals of  claim 1 , wherein each of the semiconductor nanocrystals is encapsulated within a polymer bead. 
     
     
         12 . The plurality of semiconductor nanocrystals of  claim 1 , wherein the semiconductor nanocrystals are conjugated to a biological agent or to a chemical agent. 
     
     
         13 . A solar cell comprising the plurality of semiconductor nanocrystals of  claim 1 . 
     
     
         14 . An organic light-emitting device comprising the plurality of semiconductor nanocrystals of  claim 1 . 
     
     
         15 . A solid-state light-emitting diode comprising the plurality of semiconductor nanocrystals of  claim 1 .