# US 2022/0285644 A1 · Light-emitting element and display device

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- Number: US 2022/0285644 A1
- Document ID: US20220285644A1
- Status: Published application
- Kind: A1
- Application number: 17/637,249
- Filed: 2019-09-02
- Published: 2022-09-08
- Earliest claimed: 2019-09-02
- Assignees: Sharp Kabushiki Kaisha
- Applicants: Sharp Kabushiki Kaisha
- Inventors: DAISUKE HONDA; YOSHIHIRO UETA
- Web page: https://patentgrep.com/patent/US20220285644A1

## CPC

- H10K 50/115: comprising active inorganic nanostructures, e.g. luminescent quantum dots
- H10K 50/125: specially adapted for multicolour light emission, e.g. for emitting white light
- H10K 50/15: Hole transporting layers
- H10K 50/16: Electron transporting layers
- H10K 59/1201: {Manufacture or treatment}
- H10K 71/80: using temporary substrates
- H10K 59/12: Active-matrix OLED [AMOLED] displays
- H10K 59/38: comprising colour filters or colour changing media [CCM]
- H10K 2101/80: {Composition varying spatially, e.g. having a spatial gradient}
- H10K 2102/331: {Nanoparticles used in non-emissive layers, e.g. in packaging layer}
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

A light-emitting element includes: an electron transport layer; a hole transport layer; and a light-emitting layer between the electron transport layer and the hole transport layer, the light-emitting layer including: quantum dots; and ligands coordinated to the quantum dots, wherein the ligands in the light-emitting layer have a lower concentration on an electron transport layer side of the light-emitting layer than on a hole transport layer side of the light-emitting layer.

## Claims

### Claim 1

A light-emitting element comprising:
an electron transport layer;
a hole transport layer; and
a light-emitting layer between the electron transport layer and the hole transport layer, the light-emitting layer including:
quantum dots; and
ligands coordinated to the quantum dots, wherein
the ligands in the light-emitting layer have a lower concentration on an electron transport layer side of the light-emitting layer than on a hole transport layer side of the light-emitting layer.

### Claim 2 (depends on 1)

The light-emitting element according to claim 1, wherein the concentration of the ligands in the light-emitting layer gradually decreases from the hole transport layer side to the electron transport layer side.

### Claim 3 (depends on 1)

The light-emitting element according to claim 1, wherein
the light-emitting layer has a first area on the electron transport layer side and a second area on the hole transport layer side, and
the first area has a lower conductivity than does the second area.

### Claim 4 (depends on 3)

The light-emitting element according to claim 3, wherein
the first area at least occupies half or less of a thickness of the light-emitting layer on the electron transport layer side,
the second area at least occupies less than half the thickness of the light-emitting layer on the hole transport layer side, and
letting A represent the concentration of the ligands in the first area and B represent the concentration of the ligands in the second area, a relation, B/A>4, holds.

### Claim 5 (depends on 1)

The light-emitting element according to claim 1, wherein those ligands which are coordinated to the quantum dots on the electron transport layer side are fewer than those ligands which are coordinated to the quantum dots on the hole transport layer side.

### Claim 6 (depends on 1)

The light-emitting element according to claim 1, wherein the quantum dots in the light-emitting layer have a lower density on the electron transport layer side than on the hole transport layer side.

### Claim 7 (depends on 6)

The light-emitting element according to claim 6, wherein those ligands which are coordinated to the quantum dots on the electron transport layer side are equal in number per quantum dot to those ligands which are coordinated to the quantum dots on the hole transport layer side.

### Claim 8 (depends on 1)

The light-emitting element according to claim 1, wherein the ligands contain an organic material.

### Claim 9 (depends on 1)

The light-emitting element according to claim 1, wherein the ligands contain a metal chalcogenide compound.

### Claim 10 (depends on 9)

The light-emitting element according to claim 9, wherein the metal chalcogenide compound contains any of Sn2S6, Sn2Se6, In2Se4, In2Se4, In2Te3, Ga2Se3, CuInSe2, Cu7S4, Hg3Se4, Sb2Te3, and ZnTe.

### Claim 11 (depends on 1)

The light-emitting element according to claim 1, wherein of the quantum dots, those ligands which are coordinated to the quantum dots on the electron transport layer side are of a same type as those ligands which are coordinated to the quantum dots on the hole transport layer side.

### Claim 12 (depends on 1)

A display device comprising:
a thin film transistor; and
a light-emitting element according to claim 1 electrically connected to the thin film transistor.