# US 11,444,257 B2 · Quantum dot electroluminescent element, display panel and display device

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- Number: US 11,444,257 B2
- Document ID: US11444257B2
- Status: Granted
- Kind: B2
- Application number: 17/040,964
- Filed: 2020-03-18
- Published: 2021-05-27
- Granted: 2022-09-13
- Earliest claimed: 2019-05-09
- Assignees: Beijing BOE Technology Development Co., Ltd.
- Applicants: Beijing Boe Technology Development Co., Ltd.
- Inventors: Boris Kristal
- Web page: https://patentgrep.com/patent/US11444257B2

## CPC

- H10K 50/115: comprising active inorganic nanostructures, e.g. luminescent quantum dots
- H10K 50/13: comprising stacked EL layers within one EL unit
- H10K 50/15: Hole transporting layers
- H10K 50/16: Electron transporting layers
- H10K 50/181: {Electron blocking layers}
- H10K 2102/351: {Thickness}
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

A quantum dot electroluminescent element, a display panel, and a display device are provided. The quantum dot electroluminescent element includes an anode layer, a composite light-emitting layer, and a cathode layer which are stacked. The composite light-emitting layer includes at least two quantum dot light-emitting layers which are stacked, and an intermediate layer arranged between every two adjacent ones of the at least two quantum dot light-emitting layers; the intermediate layer is configured to transport holes and block electrons.

## Claims

### Claim 1

A quantum dot electroluminescent element, comprising an anode layer, a composite light-emitting layer, and a cathode layer which are stacked,
wherein the composite light-emitting layer comprises at least two quantum dot light-emitting layers which are stacked, and an intermediate layer arranged between every two adjacent ones of the at least two quantum dot light-emitting layers; the intermediate layer is configured to transport holes and block electrons.

### Claim 2 (depends on 1)

The quantum dot electroluminescent element according to claim 1, wherein the intermediate layer is respectively in direct contact with the quantum dot light-emitting layers on both sides of the intermediate layer, and the intermediate layer consists of a material which transports holes and blocks electrons.

### Claim 3 (depends on 1)

The quantum dot electroluminescent element according to claim 1, wherein the composite light-emitting layer comprises two quantum dot light-emitting layers which are stacked.

### Claim 4 (depends on 3)

The quantum dot electroluminescent element according to claim 3, wherein the two quantum dot light-emitting layer have the same material.

### Claim 5 (depends on 3)

The quantum dot electroluminescent element according to claim 3, wherein film thicknesses of the two quantum dot light-emitting layers decrease successively in a direction from the cathode layer to the anode layer.

### Claim 6 (depends on 5)

The quantum dot electroluminescent element according to claim 5, wherein the film thickness of each of the two quantum dot light-emitting layers is greater than 5 nm and less than 15 nm.

### Claim 7 (depends on 1)

The quantum dot electroluminescent element according to claim 1, wherein the intermediate layer has a thickness less than 10 nm.

### Claim 8 (depends on 7)

The quantum dot electroluminescent element according to claim 7, wherein the composite light-emitting layer has a film thickness greater than 10 nm and less than 30 nm.

### Claim 9 (depends on 1)

The quantum dot electroluminescent element according to claim 1, wherein a material of the intermediate layer is at least one selected from the group consisting of poly[9,9-dioctylfluorene-CO—N-(4-butylphenyl)diphenylamine], polyvinyl carbazole, N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1, 1′-biphenyl-4,4′-diamine, 4,4′-bis (9-carbazole) biphenyl, N,N′-diphenyl-N,N′-(1-naphthalene)-1,1′-biphenyl-4,4′-diamine, polyaniline, and N,N′-bis(naphthalene-1-yl)-N,N′-bis(phenyl)benzidine.

### Claim 10 (depends on 1)

The quantum dot electroluminescent element according to claim 1, wherein an electron transport layer is further provided at a side of the composite light-emitting layer close to the cathode layer;
a hole transport layer is further provided between the anode layer and the composite light-emitting layer; and
a hole injection layer is further provided between the hole transport layer and the anode layer.

### Claim 11 (depends on 1)

The quantum dot electroluminescent element according to claim 1, comprising at least two light-emitting structure layers which are stacked, wherein each of the two light-emitting structure layers comprises the composite light-emitting layer, and the at least two light-emitting structure layers are configured to emit light of different colors.

### Claim 12 (depends on 11)

The quantum dot electroluminescent element according to claim 11, wherein a charge generation layer is provided between two adjacent ones of the at least two light-emitting structure layers, and the charge generation layer comprises an n-type doped organic layer and a p-type doped organic layer.

### Claim 13 (depends on 11)

The quantum dot electroluminescent element according to claim 11, wherein each of the at least two light-emitting structure layers further comprises a hole injection layer and a hole transport layer on a side of the composite light-emitting layer close to the anode layer, and an electron transport layer on a side of the composite light-emitting layer close to the cathode layer.

### Claim 14 (depends on 1)

A quantum dot electroluminescent display panel, comprising a plurality of pixel units arranged in an array, wherein each of the plurality of pixel units comprises the quantum dot electroluminescent element according to claim 1.

### Claim 15 (depends on 14)

A display device, comprising the quantum dot electroluminescent display panel according to claim 14.