Low-temperature synthesis of colloidal nanocrystals

Abstract

Low-temperature organometallic nucleation and crystallization-based synthesis methods for the fabrication of semiconductor and metal colloidal nanocrystals with narrow size distributions and tunable, size- and shape-dependent electronic and optical properties. Methods include (1) forming a reaction mixture in a reaction vessel under an inert atmosphere that includes at least one solvent, a cationic precursor, an anionic precursor, and at least a first surface stabilizing ligand while stirring at a temperature in a range from about 50° C. to about 130° C. and (2) growing nanocrystals in the reaction mixture for a period of time while maintaining the temperature, the stirring, and the inert-gas atmosphere.

What is claimed is: 
     
         1 . A chemical composition, comprising
 an amount of semiconductor nanocrystals, each semiconductor nanocrystal having a size greater than 1 nm and less than about 40 nm resulting in three-dimensional quantum confinement of created excitons within the semiconductor nanocrystal, the semiconductor nanocrystal including:
 a Group III, Group IV, Group VIIIB, Group IB, or Group IIB cationic metal; 
 a Group V or Group VI anion selected from the group consisting of a sulfide, selenide, telluride, phosphide, nitride, arsenide, and combinations thereof; and 
   at least a residual amount of a synthesis solvent having a boiling point in a range from about 80° C. to about 350° C.   
     
     
         2 . The chemical composition of  claim 1 , wherein the synthesis solvent has a boiling point in a range from about 100° C. to about 300° C. 
     
     
         3 . The chemical composition of  claim 1 , wherein the synthesis solvent has a boiling point in a range from about 110° C. to about 280° C. 
     
     
         4 . The chemical composition of  claim 1 , wherein the synthesis solvent is selected from the group consisting of an alkane, an alkene, a phenyl ether, a chloro alkane, a fluoro alkane, toluene, and squalene. 
     
     
         5 . The chemical composition of  claim 4 , wherein the synthesis solvent comprises octadecene. 
     
     
         6 . The chemical composition of  claim 1 , further comprising a surface stabilizing ligand. 
     
     
         7 . The chemical composition of  claim 6 , wherein the surface stabilizing ligand is an alkyl amine having an aliphatic chain that includes at least four carbon atoms. 
     
     
         8 . The chemical composition of  claim 1 , wherein the Group III, Group IV, Group VIIIB, Group IB, or Group IIB cationic metal includes at least one of iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, mercury, aluminum, gallium, indium, silicon, germanium, tin, or lead. 
     
     
         9 . The chemical composition of  claim 8 , wherein the Group III, Group IV, Group VIIIB, Group IB, or Group IIB cationic metal includes at least one of cadmium, lead, zinc, mercury, gold, silver, cobalt, platinum, nickel, iron, or copper. 
     
     
         10 . The chemical composition of  claim 1 , wherein semiconductor nanocrystals are suspended in a material. 
     
     
         11 . The chemical composition of  claim 10 , wherein the material is a storage solvent. 
     
     
         12 . A chemical composition comprising at least a residual amount of a synthesis solvent and an amount of semiconductor nanocrystals formed according to the method of:
 forming a first solution under an inert-gas atmosphere at a temperature of at least 35° C., the first solution comprising a cationic precursor and one of an alkyl carboxylic acid or an alkyl phosphonic acid, and a solvent selected from the group consisting of an alkane, an alkene, a phenyl ether, a chloro alkane, a fluoro alkane, toluene, and squalene;   forming a second solution under an inert-gas atmosphere at ambient temperature, the second solution comprising a Group V or Group VI anionic precursor, a phosphine, and a solvent selected from the group consisting of an alkane, an alkene, a phenyl ether, a chloro alkane, a fluoro alkane, toluene, and squalene, wherein the Group V or Group VI anionic precursor is at least one sulfide, selenide, telluride, phosphide, nitride, or arsenide;   forming a third solution under an inert-gas atmosphere at a temperature of at least 35° C., the third solution comprising an alkyl amine having an aliphatic chain that includes at least four carbon atoms and a solvent selected from the group consisting of an alkane, an alkene, a phenyl ether, a chloro alkane, a fluoro alkane, toluene, and squalene;   combining at least a portion of the first and second solutions into the third solution to initiate growth of the semiconductor nanocrystals; and   growing semiconductor nanocrystals for a period of time between about 1 minute and about 96 hours at a temperature in a range of about 35° C. to about 130° C.   
     
     
         13 . The chemical composition of  claim 12 , wherein the cationic precursor comprises a Group III, Group IV, Group VIIIB, Group IB, or Group IIB metal. 
     
     
         14 . The chemical composition of  claim 13 , wherein the Group III, Group IV, Group VIIIB, Group IB, or Group IIB cationic metal includes at least one of iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, mercury, aluminum, gallium, indium, silicon, germanium, tin, or lead. 
     
     
         15 . The chemical composition of  claim 14 , wherein the Group III, Group IV, Group VIIIB, Group IB, or Group IIB cationic metal includes at least one of cadmium, lead, zinc, mercury, gold, silver, cobalt, platinum, nickel, iron, or copper. 
     
     
         16 . The chemical composition of  claim 12 , wherein the alkyl amine comprises octadecylamine. 
     
     
         17 . The chemical composition of  claim 12 , wherein the cationic precursor comprises a metallic C 2 -C 20  carboxylic acid salt. 
     
     
         18 . The chemical composition of  claim 12 , wherein the method further comprises one of:
 adding the first and second solutions into the third solution substantially simultaneously;   adding the first solution into the third solution and then adding the second solution into the third solution; or   adding the second solution into the third solution and then adding the first solution into the third solution.