Patent ID: 7767260

Claim:
A method for preparing core/shell nanocrystals having the formula M 1 X 1 /M 2 X 2 , comprising: a) providing a solution of core nanocrystals of the formula M 1 X 1 in a reaction vessel; b) forming a first monolayer of a shell material M 2 X 2 by contacting the core nanocrystals with a cation (M 2 ) precursor solution in an amount effective to form a monolayer of the cation, and contacting the core nanocrystals having a monolayer of the cation with an anion (X 2 ) precursor solution in an amount effective to form a monolayer of the anion wherein the cation (M 2 ) precursor solution and the anion (X 2 ) precursor solution are added to the reaction vessel in an alternating manner; c) forming a subsequent monolayer of the shell material M 2 X 2 by contacting the core/shell nanocrystals with the cation precursor solution (M 2 )in an amount effective to form a monolayer of the cation, and contacting the core/shell nanocrystals having a monolayer of the cation with the anion (X 2 ) precursor solution in an amount effective to form a monolayer of the anion, wherein the cation (M 2 ) precursor solution and the anion (X 2 ) precursor solution are added to the reaction vessel in an alternating manner; wherein M 1 X 1 comprises a stable, nanometer-sized inorganic solid; wherein M 2 X 2 is selected from a II/VI compound or a III/V compound; wherein M 1 X 1 and M 2 X 2 are different; and wherein the solution of nanocrystals in each coating step is used as prepared in the previous coating step.