# US 2020/0403174 A1 · Quantum-dot light emitting diode, method of fabricating the quantum-dot light emitting diode and quantum-dot light emitting display device

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- Number: US 2020/0403174 A1
- Document ID: US20200403174A1
- Status: Published application
- Kind: A1
- Application number: 16/909,912
- Filed: 2020-06-23
- Published: 2020-12-24
- Earliest claimed: 2019-06-24
- Assignees: LG Display Co., Ltd.; Korea Advanced Institute of Science and Technology
- Applicants: LG Display Co., Ltd.; Korea Advanced Institute of Science and Technology
- Inventors: Kyu-Nam KIM; Duk-Young JEON; Hyun-Jin CHO; Sun-Joong PARK
- Web page: https://patentgrep.com/patent/US20200403174A1

## CPC

- H10K 50/11: characterised by the electroluminescent [EL] layers
- H10K 50/115: comprising active inorganic nanostructures, e.g. luminescent quantum dots
- H10K 50/15: Hole transporting layers
- H10K 85/114: {Poly-phenylenevinylene; Derivatives thereof}
- H10K 59/12: Active-matrix OLED [AMOLED] displays
- H10K 59/1201: {Manufacture or treatment}
- H10K 85/1135: {Polyethylene dioxythiophene [PEDOT]; Derivatives thereof}
- H10K 85/115: {Polyfluorene; Derivatives thereof}
- H10K 85/146: {poly N-vinylcarbazol; Derivatives thereof}
- H10K 85/151: {Copolymers}
- H10K 85/631: {Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine}
- H10K 85/636: {comprising heteroaromatic hydrocarbons as substituents on the nitrogen atom}
- H10K 85/6572: {comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole}
- H10K 2101/30: Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values
- H10K 2101/40: Interrelation of parameters between multiple constituent active layers or sublayers, e.g. HOMO values in adjacent layers
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

The present disclosure provides a quantum dot (QD) light emitting diode including: a first electrode; a second electrode facing the first electrode; a QD emitting material layer positioned between the first electrode and the second electrode and including a QD and an organic material; a hole auxiliary layer positioned between the first electrode and the QD emitting material layer; and an electron auxiliary layer positioned between the QD emitting material layer and the second electrode, wherein the organic material has a highest occupied molecular orbital (HOMO) level higher than a material of the hole auxiliary layer.

## Claims

### Claim 1

A quantum dot (QD) light emitting diode, comprising:
a first electrode;
a second electrode facing the first electrode;
a QD emitting material layer positioned between the first electrode and the second electrode and including a QD and an organic material;
a hole auxiliary layer positioned between the first electrode and the QD emitting material layer; and
an electron auxiliary layer positioned between the QD emitting material layer and the second electrode,
wherein the organic material has a highest occupied molecular orbital (HOMO) level higher than a material of the hole auxiliary layer.

### Claim 2 (depends on 1)

The QD light emitting diode according to claim 1, wherein in the QD emitting material layer, an amount of the organic material is smaller than that of the QD.

### Claim 3 (depends on 2)

The QD light emitting diode according to claim 2, wherein the organic material has a weight % of 3 to 6 with respect to the QD.

### Claim 4 (depends on 1)

The QD light emitting diode according to claim 1, wherein a HOMO level of the organic material has a range of −5.5 to −5.0 eV, and a HOMO level of the material of the hole auxiliary layer has a range of −6.0 to −5.5 eV, and
wherein a valence band level of the QD has a range of −6.5 to −6.0 eV.

### Claim 5 (depends on 1)

The QD light emitting diode according to claim 1, wherein the organic material is tris(4-carbazoyl-9-ylphenyl)amine (TCTA) or 4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (TPD), and the material of the hole auxiliary layer is poly-N-vinylcarbazole (PVK) or poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenyl amine)] (TFB).

### Claim 6 (depends on 1)

The QD light emitting diode according to claim 1, wherein a lowest unoccupied molecular orbital (LUMO) level of the organic material is higher than a conduction band level of the QD.

### Claim 7

A QD light emitting display device, comprising:
a substrate;
a QD light emitting diode positioned on or over the substrate, the QD light emitting diode including:
a first electrode;
a second electrode facing the first electrode;
a QD emitting material layer positioned between the first electrode and the second electrode and including a QD and an organic material;
a hole auxiliary layer positioned between the first electrode and the QD emitting material layer; and
an electron auxiliary layer positioned between the QD emitting material layer and the second electrode; and
a thin film transistor positioned between the substrate and the QD light emitting diode and connected to the QD light emitting diode,
wherein the organic material has a HOMO level higher than a material of the hole auxiliary layer.

### Claim 8 (depends on 7)

The QD light emitting display device according to claim 7, wherein in the QD emitting material layer, an amount of the organic material is smaller than that of the QD.

### Claim 9 (depends on 8)

The QD light emitting display device according to claim 8, wherein the organic material has a weight % of 3 to 6 with respect to the QD.

### Claim 10 (depends on 7)

The QD light emitting display device according to claim 7, wherein a HOMO level of the organic material has a range of −5.5 to −5.0 eV, and a HOMO level of the material of the hole auxiliary layer has a range of −6.0 to −5.5 eV, and
wherein a valence band level of the QD has a range of −6.5 to −6.0 eV.

### Claim 11 (depends on 7)

The QD light emitting display device according to claim 7, wherein the organic material is tris(4-carbazoyl-9-ylphenyl)amine (TCTA) or 4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (TPD), and the material of the hole auxiliary layer is poly-N-vinylcarbazole (PVK) or poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenyl amine)] (TFB).

### Claim 12 (depends on 7)

The QD light emitting display device according to claim 7, wherein a LUMO level of the organic material is higher than a conduction band level of the QD.

### Claim 13

A method of fabricating a QD light emitting diode, comprising:
forming a first electrode;
forming a hole auxiliary layer of a hole auxiliary material on the first electrode;
forming a QD emitting material layer on the hole auxiliary layer by coating an emitting material solution, wherein the emitting material solution includes a QD, an organic material and a solvent;
forming an electron auxiliary layer on the QD emitting material layer; and
forming a second electrode on the electron auxiliary layer,
wherein the organic material has a HOMO level higher than the hole auxiliary material.

### Claim 14 (depends on 13)

The method according to claim 13, wherein in the emitting material solution, an amount of the organic material is smaller than that of the QD.

### Claim 15 (depends on 14)

The method according to claim 14, wherein the organic material has a weight % of 3 to 6 with respect to the QD.

### Claim 16 (depends on 13)

The method according to claim 13, wherein a HOMO level of the organic material has a range of −5.5 to −5.0 eV, and a HOMO level of the hole auxiliary material has a range of −6.0 to −5.5 eV, and
wherein a valence band level of the QD has a range of −6.5 to −6.0 eV.

### Claim 17 (depends on 13)

The method according to claim 13, wherein the organic material is tris(4-carbazoyl-9-ylphenyl)amine (TCTA) or 4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (TPD), and the hole auxiliary material is poly-N-vinylcarbazole (PVK) or poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (TFB).

### Claim 18 (depends on 13)

The method according to claim 13, wherein a lowest unoccupied molecular orbital (LUMO) level of the organic material is higher than a conduction band level of the QD.

### Claim 19 (depends on 13)

The method according to claim 13, wherein the solvent includes a non-polar solvent and a polar solvent, and an amount of the polar solvent is smaller than that of the non-polar solvent.

### Claim 20 (depends on 19)

The method according to claim 19, wherein the polar solvent has a weight % of 3 to 6 with respect to the non-polar solvent.