Highly luminescent nanostructures and methods of producing same
Highly luminescent nanostructures, particularly highly luminescent quantum dots, are provided. The nanostructures have high photoluminescence quantum yields and in certain embodiments emit light at particular wavelengths and have a narrow size distribution. The nanostructures can comprise ligands, including C5-C8 carboxylic acid ligands employed during shell formation and/or dicarboxylic or polycarboxylic acid ligands provided after synthesis. Processes for producing such highly luminescent nanostructures are also provided, including methods for enriching nanostructure cores with indium and techniques for shell synthesis.
1. A method for production of core/shell, nanostructures, the method comprising:
providing a nanostructure core; and
producing a shell surrounding the core by providing one or more precursors and reacting the precursors in the presence of a C5-C8 carboxylic acid ligand to produce the shell, wherein a C5-C8 carboxylic ligand is bound to a surface of the nanostructure core, and wherein the core/shell nanostructures are InP/ZnS x Se 1-x /ZnS core/shell quantum dots, where 0<x<1.
2. The method of claim 1 , wherein the ligand is an alkyl carboxylic acid.
3. The method of claim 1 , wherein the ligand is an unbranched alkyl carboxylic acid.
4. The method of claim 1 , wherein the ligand is hexanoic acid.
5. The method of claim 1 , wherein the ligand is pentanoic acid.
6. The method of claim 1 , wherein the ligand is an alkenyl carboxylic acid or an alkynyl carboxylic acid.
7. The method of claim 1 , wherein the ligand is 4-pentenoic acid.
8. The method of claim 1 , wherein the ligand is an unbranched monocarboxylic acid.
9. The method of claim 1 , wherein reacting the precursors in the presence of a C5-C8 carboxylic acid ligand comprises reacting the precursors in the presence of a C5-C8 carboxylic acid ligand and a long chain fatty acid ligand, which long chain fatty acid comprises at least 12 carbon atoms.
10. The method of claim 1 , wherein the shell comprises at least two layers; and wherein providing one or more precursors and reacting the precursors in the presence of a C5-C8 carboxylic acid ligand to produce the shell comprises providing a first set of one or more precursors and reacting the precursors in the presence of the C5-C8 carboxylic acid ligand to produce a first layer of the shell, and then providing a second set of one or more precursors and reacting the precursors in the presence of the C5-C8 carboxylic acid Ligand to produce a second layer of the shell.
11. The method of claim 10 , wherein 0.25<x<0.75.
12. The method of claim 11 , Wherein x is about 0.5.
13. The method of claim 10 , wherein the first set of precursors comprises diethyl zinc, bis(trimethylsilyl)selenide, and hexamethyldisilthiane.
14. The method of claim 10 , wherein the second set of precursors comprises diethyl zinc and hexamethyldisilthiane.
15. The method of claim 1 , comprising, after producing the shell, exchanging the ligand with a dicarboxylic or polycarboxylic acid ligand.
16. The method of claim 15 , wherein the dicarboxylic or polycarboxylic acid ligand is dodecenyl succinic acid.