# US 8,784,703 B2 · Method of making highly-confined semiconductor nanocrystals

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- Number: US 8,784,703 B2
- Document ID: US8784703B2
- Status: Granted
- Kind: B2
- Application number: 13/275,595
- Filed: 2011-10-18
- Published: 2013-04-18
- Granted: 2014-07-22
- Earliest claimed: 2011-10-18
- Assignees: Eastman Kodak Company
- Applicants: Keith Brian Kahen; Matthew Holland; Sudeep Pallikkara Kuttiatoor
- Inventors: Keith Brian Kahen; Matthew Holland; Sudeep Pallikkara Kuttiatoor
- Web page: https://patentgrep.com/patent/US8784703B2

## CPC

- C09K 11/02: Use of particular materials as binders, particle coatings or suspension media therefor
- C09K 11/565: {with zinc cadmium}
- C09K 11/70: containing phosphorus
- C09K 11/883: {with zinc or cadmium}
- H10H 20/8512: {Wavelength conversion materials}
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS

## Abstract

A method of making a colloidal solution of high confinement semiconductor nanocrystals includes: forming a first solution by combining a solvent, growth ligands, and at most one semiconductor precursor; heating the first solution to the nucleation temperature; and adding to the first solution, a second solution having a solvent, growth ligands, and at least one additional and different precursor than that in the first solution to form a crude solution of nanocrystals having a compact homogenous semiconductor region. The method further includes: waiting 0.5 to 20 seconds and adding to the crude solution a third solution having a solvent, growth ligands, and at least one additional and different precursor than those in the first and second solutions; and lowering the growth temperature to enable the formation of a gradient alloy region around the compact homogenous semiconductor region, resulting in the formation of a colloidal solution of high confinement semiconductor nanocrystals.

## Claims

### Claim 1

A method of making a colloidal solution of high confinement semiconductor nanocrystals, comprising:
(a) forming a first solution by combining a solvent, growth ligands, and at most one semiconductor precursor;
(b) heating the first solution to a nucleation temperature;
(c) adding to the first solution, a second solution having a solvent, growth ligands, and at least one additional and different precursor that includes binary or ternary II-VI, III-V, or IV-VI semiconductor materials in the first solution to form a crude solution of nanocrystals having a compact homogenous semiconductor region;
(d) waiting for 0.5 to 20 seconds and then adding to the crude solution a third solution having a solvent, growth ligands, and at least one additional and different precursor than those in the first and second solutions and includes ternary or quaternary II-VI, III-V, or IV-VI semiconductor materials;
(e) lowering the nucleation temperature to a growth temperature to enable the formation of a gradient alloy region around the compact homogenous semiconductor region, resulting in the formation of a colloidal solution of high confinement semiconductor nanocrystals.

### Claim 2 (depends on 1)

The method of claim 1 further comprising forming single or multiple shell layers on the high confinement semiconductor nanocrystals.

### Claim 3 (depends on 2)

The method claim 2 wherein the shell layers are grown to a thickness of 1 to 20 monolayers.

### Claim 4 (depends on 2)

The method of claim 2 wherein the shells include binary, ternary, or quaternary II-VI, III-V, or IV-VI semiconductor material, or combinations thereof.

### Claim 5 (depends on 1)

The method of claim 1 wherein the nucleation temperature is between 250 to 320° C.

### Claim 6 (depends on 1)

The method of claim 1 wherein in step (e) the temperature is lowered by 10 to 50° C.

### Claim 7 (depends on 1)

The method of claim 1 further comprising:
(f) adding a weak acid to the crude solution containing the high confinement nanocrystals;
(g) annealing the crude solution at a temperature in a range from 180 to 260° C.; and
(h) adding ligands to the solution to prevent aggregation of the nanocrystals.

### Claim 8 (depends on 7)

The method of claim 7 wherein the weak acid is acetic acid.