Methods for the preparation of luminescent nanoparticles using two solvents

Abstract

Methods for synthesizing luminescent nanoparticles and nanoparticles prepared by such methods are provided. The nanoparticles are prepared by a method in which an additive is included in the reaction mixture. The additive may be a Group 2 element, a Group 12 element, a Group 13 element, a Group 14 element, a Group 15 element, or a Group 16 element. In additions, a luminescent nanoparticle is provided that comprises a semiconductive core surrounded by an inorganic shell, an interfacial region and an additive present in the interfacial region or both the interfacial region and the shell.

1 . A method of preparing a luminescent nanoparticle, the method comprising the steps: 
 providing a semiconductive core in a first solvent;    isolating the semiconductive core;    admixing the semiconductive core, a first shell precursor, a second shell precursor, a second solvent, and an additive comprising an element selected from the group consisting of a Group 2 element, a Group 12 element, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, Fe, Nb, Cr, Mn, Co, Cu, and Ni, to form a reaction dispersion; and    heating the reaction dispersion to a temperature for a period of time sufficient to induce formation of an inorganic shell on the semiconductive core;    wherein the first solvent and the second solvent are different; and    the first shell precursor and the second shell precursor are different.    
     
     
         2 . The method of  claim 1 , wherein the second solvent and the additive are admixed with the semiconductive core prior to addition of the first shell precursor and the second shell precursor.  
     
     
         3 . The method of  claim 1 , wherein the heating step is performed concurrent with the addition of the first shell precursor and second shell precursor.  
     
     
         4 . The method of  claim 1 , wherein the second solvent is admixed with the semiconductive core prior to addition of the first shell precursor, the second shell precursor, and the additive.  
     
     
         5 . The method of  claim 1 , wherein the second solvent, the first shell precursor, and the additive are admixed with the semiconductive core prior to addition of the second shell precursor.  
     
     
         6 . The method of  claim 1 , wherein the semiconductive core comprises a material selected from the group consisting of MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, Al 2 S 3 , Al 2 Se 3 , Al 2 Te 3 , Ga 2 S 3 , Ga 2 Se 3 , Ga 2 Te 3 , In 2 S 3 , In 2 Se 3 , In 2 Te 3 , SnS, SnSe, SnTe, PbS, PbSe, PbTe, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, BP, Si, and Ge, and ternary and quaternary mixtures, compounds, and solid solutions thereof.  
     
     
         7 . The method of  claim 1 , wherein the semiconductive core comprises a material selected from the group consisting of CdSe, CdTe, CdS, ZnSe, InP, InAs, and PbSe.  
     
     
         8 . The method of  claim 1 , wherein the inorganic shell comprises a material selected from the group consisting of MgO, MgS, MgSe, MgTe, CaO, CaS, CaSe, CaTe, SrO, SrS, SrSe, SrTe, BaO, BaS, BaSe, BaTe, ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgO, HgS, Al 2 O 3 , Al 2 S 3 , Al 2 Se 3 , Al 2 Te 3 , Ga 2 O 3 , Ga 2 S 3 , Ga 2 Se 3 , Ga 2 Te 3 , In 2 O 3 , In 2 S 3 , In 2 Se 3 , In 2 Te 3 , SiO 2 , GeO 2 , SnO, SnO 2 , SnS, SnSe, SnTe, PbO, PbO2, PbS, PbSe, PbTe, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, BP, and ternary and quaternary mixtures, compounds, and solid solutions thereof.  
     
     
         9 . The method of  claim 1 , wherein the inorganic shell comprises a material selected from the group consisting of CdSe, CdS, ZnSe, ZnS, CdO, ZnO, SiO 2 , Al 2 O 3 , and ZnTe.  
     
     
         10 . The method of  claim 1 , wherein: 
 the semiconductive core comprises a material selected from the group consisting of CdSe, CdTe, CdS, ZnSe, InP, InAs, and PbSe; and    the inorganic shell is selected from the group consisting of CdSe, CdS, ZnSe, ZnS, CdO, ZnO, SiO 2 , Al 2 O 3 , and ZnTe.    
     
     
         11 . The method of  claim 1 , wherein: 
 the semiconductive core is CdSe or CdTe;    the inorganic shell is ZnS; and    the additive is Cd.    
     
     
         12 . The method of  claim 1 , wherein: 
 the inorganic shell is CdS; and    the additive is Zn.    
     
     
         13 . The method of  claim 1 , wherein the first solvent and second solvent are independently selected from the group consisting of acids, fatty acids, amines, phosphines, phosphine oxides, phosphonic acids, phosphoramides, phosphates, and mixtures thereof.  
     
     
         14 . The method of  claim 1 , wherein the first solvent and second solvent are independently selected from the group consisting of alkanes, alkenes, halo-alkanes, ethers, alcohols, ketones, esters, and mixtures thereof.  
     
     
         15 . The method of  claim 1 , wherein the heating step comprises heating the reaction dispersion to a temperature of about 50° C. to about 300° C.  
     
     
         16 . The method of  claim 1 , wherein the heating step comprises heating the reaction dispersion to a temperature of about 100° C. to about 300° C.