# US 11,908,979 B2 · Chelating agents for quantum dot precursor materials in color conversion layers for micro-LEDs

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- Number: US 11,908,979 B2
- Document ID: US11908979B2
- Status: Granted
- Kind: B2
- Application number: 17/901,831
- Filed: 2022-09-01
- Published: 2023-01-05
- Granted: 2024-02-20
- Earliest claimed: 2020-08-28
- Assignees: Applied Materials, Inc.
- Applicants: Applied Materials, Inc.
- Inventors: Yingdong Luo; Daihua Zhang; Hou T. Ng; Sivapackia Ganapathiappan; Nag B. Patibandla
- Web page: https://patentgrep.com/patent/US11908979B2

## CPC

- H10H 20/8511: {characterised by their material, e.g. binder}
- H10H 20/8513: {having two or more wavelength conversion materials}
- C08F 2/44: Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers
- C08F 2/48: by ultraviolet or visible light
- C08F 2/50: with sensitising agents
- C09K 11/02: Use of particular materials as binders, particle coatings or suspension media therefor
- H10H 20/824: comprising only Group III-V materials, e.g. GaP
- H10H 29/142: {Two-dimensional arrangements, e.g. asymmetric LED layout}
- H10W 90/00: Package configurations
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A photocurable composition includes quantum dots, quantum dot precursor materials, a chelating agent, one or more monomers, and a photoinitiator. The quantum dots are selected to emit radiation in a first wavelength band in the visible light range in response to absorption of radiation in a second wavelength band in the UV or visible light range. The second wavelength band is different than the first wavelength band. The quantum dot precursor materials include metal atoms or metal ions corresponding to metal components present in the quantum dots. The chelating agent is configured to chelate the quantum dot precursor materials. The photoinitiator initiates polymerization of the one or more monomers in response to absorption of radiation in the second wavelength band.

## Claims

### Claim 1

A method of fabricating a light-emitting device, the method comprising:
ejecting a photocurable composition onto an array of micro-LEDs that are integrated with backplane circuitry, wherein the photocurable composition includes quantum dots, quantum dot precursor materials that comprise metal atoms or metal ions corresponding to metal components present in the quantum dots, a chelating agent configured to chelate the quantum dot precursor materials, one or more monomers, and a photoinitiator;
activating a plurality of micro-LEDs from the array of micro-LEDs to illuminate the photocurable composition over the plurality of micro-LEDs with light in a second wavelength band in the UV or visible light range that causes the photoinitiator to initiate polymerization of the one or more monomers and causes the quantum dots to emit light in a different first wavelength band in the visible light range; and
removing an uncured portion of the photocurable composition from the array of micro-LEDs.

### Claim 2 (depends on 1)

The method of claim 1, wherein the photocurable composition comprises:
about 0.1 wt % to about 10 wt % of the quantum dots;
about 0.0001 wt % to about 10 wt % of the chelating agent;
about 0.5 wt % to about 5 wt % of the photoinitiator; and
about 1 wt % to about 90 wt % of the one or more monomers.

### Claim 3 (depends on 2)

The method of claim 2, wherein the photocurable composition comprises about 1 wt % to about 2 wt % of the quantum dots.

### Claim 4 (depends on 1)

The method of claim 1, wherein the photocurable composition further comprises a solvent.

### Claim 5 (depends on 4)

The method of claim 4, wherein the photocurable composition comprises:
about 0.1 wt % to about 10 wt % of the quantum dots;
about 0.0001 wt % to about 10 wt % of the chelating agent;
about 0.5 wt % to about 5 wt % of the photoinitiator;
about 1 wt % to about 10 wt % of the one or more monomers; and
about 10 wt % to about 90 wt % of the solvent.

### Claim 6 (depends on 5)

The method of claim 5, wherein the photocurable composition comprises about 2 wt % to about 3 wt % of the one or more monomers.

### Claim 7 (depends on 1)

The method of claim 1, wherein the quantum dots comprise one or more III-V compounds.

### Claim 8 (depends on 7)

The method of claim 7, wherein each of the quantum dots comprises one or more ligands coupled to an exterior surface of the quantum dot, wherein the ligands are selected from the group consisting of thioalkyl compounds and carboxyalkanes.

### Claim 9 (depends on 1)

The method of claim 1, wherein the first wavelength band is red, green or blue light.

### Claim 10 (depends on 1)

The method of claim 1, wherein the chelating agent comprises a mono-thiol, a di-thiol, a thiocarbamate, a dithiocarbamate, a thiocarbonate, or a thiourea.

### Claim 11 (depends on 10)

The method of claim 10, wherein the chelating agent comprises a mono-thiol selected from the group consisting of ethanethiol, propanethiols, butanethiols, pentanethiols, 1-hexadecanethiol, 2-ethylhexanethiol, 8-mercapto-1-octanol, 2-(2-methoxyethoxy)ethanethiol, 2-(trimethylsilyl)ethanethiol, 2-propene-1-thiol, thiophenols, dimercaptosuccinic acid, thioglycolic acid, thioacetic acid, glutathione, cysteine, mercaptoethanols, dithiothreitol/dithioerythritol, 2-mercaptoethanol, 2-mercaptoindole, furan-2-ylmethanethiol, 3-mercaptopropane-1,2-diol, 3-mercapto-1-propanesulfonic acid, 1-hexadecanethiol, and pentachlorobenzenethiol.

### Claim 12 (depends on 10)

The method of claim 10, wherein the chelating agent comprises a di-thiol selected from the group consisting of 1-dithiols, 1,2-dithiols, and 1,3-dithiols, 1,2-benzene-dimethanethiol, 1,3-benzenedimethanethiol, 1,4-benzenedimethanethiol, 2,2′-(ethylenedioxy)diethanethiol, ethylene glycol bis-mercaptoacetate, tetra(ethylene glycol)dithiol, hexa(ethylene glycol)dithiol, 2,2′-thiodiethanethiol, and 1,16-hexadecanedithiol.

### Claim 13 (depends on 10)

The method of claim 10, wherein the chelating agent comprises a thiocarbamate selected from the group consisting of R1R2N(C═S)OR3, where each of R1, R2, and R3 is independently H, benzyl, substituted phenyl groups, C1-C16 linear or branched aliphatic chains, ethylene oxide oligomers, propylene oxide oligomers, copolymers of ethylene oxide and propylene oxide, and dimethylsiloxane oligomers.

### Claim 14 (depends on 10)

The method of claim 10, wherein the chelating agent comprises a dithiocarbamate selected from the group consisting of R1R2N(C═S)SR3, where each of R1, R2 and R3 is independently H, benzyl, substituted phenyl groups, C1-C16 linear or branched aliphatic chains, ethylene oxide oligomers, propylene oxide oligomers, copolymers of ethylene oxide and propylene oxide, and dimethylsiloxane oligomers.

### Claim 15 (depends on 10)

The method of claim 10, wherein the chelating agent comprises a thiocarbonate selected from the group consisting of R1O(C═O)S R2, where each of R1 and R2 is independently H, benzyl, substituted phenyl groups, C1-C16 linear or branched aliphatic chains, ethylene oxide oligomers, propylene oxide oligomers, copolymers of ethylene oxide and propylene oxide, and dimethylsiloxane oligomers.

### Claim 16 (depends on 10)

The method of claim 10, wherein the chelating agent comprises a thiourea selected from the group consisting of R1R2N(C═S)NR3R4, where each of R1, R2, R3, and R4 is independently H, benzyl, substituted phenyl groups, C1-C16 linear or branched aliphatic chains, ethylene oxide oligomers such as —(CH2CH2—O)n— with n=1˜50, propylene oxide oligomers such as —(CH2CH(CH3)—O)n— with n=1˜50, copolymers of ethylene oxide and propylene oxide, or dimethylsiloxane oligomers.

### Claim 17 (depends on 1)

The method of claim 1, wherein the chelating agent comprises a di-amine, an amino acid, an amino alcohol, guanidine, or urea.

### Claim 18 (depends on 1)

The method of claim 1, wherein the chelating agent comprises an alcohol or an acid.

### Claim 19 (depends on 1)

The method of claim 1, wherein a surface tension of the photocurable composition is in a range of about 20 mN/m to about 60 mN/m.

### Claim 20 (depends on 1)

The method of claim 1, wherein the one or more monomers comprise (meth)acrylate monomers.

### Claim 21 (depends on 1)

The method of claim 1, comprising depositing the photocurable composition to a thickness of about 10 nm to about 100 microns.

### Claim 22 (depends on 1)

The method of claim 1, further comprising:
ejecting a second photocurable composition onto the array of micro-LEDs, wherein the second photocurable composition includes second quantum dots, second quantum dot precursor materials that comprise metal atoms or metal ions corresponding to metal components present in the quantum dots, a chelating agent configured to chelate the quantum dot precursor materials, one or more monomers, and a photoinitiator;
activating a second plurality of micro-LEDs from the array of micro-LEDs to illuminate the photocurable composition over the second plurality of micro-LEDs with light in the second wavelength band that causes the photoinitiator to initiate polymerization of the one or more monomers and causes the quantum dots to emit light in a different third wavelength band in the visible light range; and
removing an uncured portion of the second photocurable composition from the array of micro-LEDs.