Quantum dot light emitting device including ligand-substituted quantum dot light emitting layer with polymer having amine groups and method for fabricating the same

Patent metadata

Field	Value
Publication number	US-10892433-B2
Application number	US-201715612768-A
Country	US
Kind code	B2
Filing date	Jun 2, 2017
Priority date	Jun 3, 2016
Publication date	Jan 12, 2021
Grant date	Jan 12, 2021

Abstract

Disclosed is a quantum dot light emitting device including a ligand-substituted quantum dot light emitting layer with a polymer having amine groups. The introduction of the ligand-substituted quantum dot light emitting layer with a polymer having amine groups changes the energy level of an electron transport layer and enables control over the charge injection properties of the device so that the flow of electrons can be controlled. In addition, the ligand substitution is effective in removing oleic acid as a stabilizer of quantum dots to prevent an increase in driving voltage caused by the introduction of the additional material, achieving markedly improved efficiency of the device. Also disclosed is a method for fabricating the quantum dot light emitting device.

First claim

What is claimed is:

1. A quantum dot light emitting device comprising:
an electron transport layer;
a polymer layer having amine groups coated on the electron transport layer; and
a quantum dot light emitting layer formed by coating quantum dots on the polymer layer;
wherein the quantum dots have surface oleic acid ligands,
wherein at least part of the quantum dot surface oleic acid ligands in contact with the polymer are ligand-substituted with said amine groups,
wherein said polymer is a dendrimer,
wherein said amine groups are positioned at branch terminus of the dendrimer,
wherein said dendrimer is a generation 3 or 4 dendrimer, and
wherein the quantum dots are bonded to said amine groups of the dendrimer by ligand substitution.

2. The quantum dot light emitting device according to claim 1 , wherein the dendrimer is a polyamidoamine dendrimer.

3. The quantum dot light emitting device according to claim 1 , wherein the quantum dot light emitting layer has a multilayer structure consisting of 1 to 10 layers.

4. The quantum dot light emitting device according to claim 1 , wherein the electron transport layer is formed of an oxide selected from ZnO, TiO 2 , WO 3 , and SnO 2 .

5. The quantum dot light emitting device according to claim 1 , wherein the quantum dot light emitting layer comprises a nano-sized semiconductor compound of Groups 2-6 or 3-5 elements.

6. The quantum dot light emitting device according to claim 5 , wherein the nano-sized semiconductor compound comprises cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), zinc selenide (ZnSe), zinc telluride (ZnTe), zinc sulfide (ZnS), mercury telluride (HgTe), indium arsenide (InAs), indium phosphide (InP), gallium arsenide (GaAs) or a combination thereof.

7. A method for fabricating a quantum dot light emitting device, comprising (a) forming an electron transport layer on a substrate, (b) coating a polymer having amine groups on the electron transport layer to form a polymer layer, and (c) coating quantum dots on the polymer layer to form a quantum dot light emitting layer,
wherein the quantum dots have surface oleic acid ligands,
wherein at least part of the quantum dot surface oleic acid ligands in contact with the polymer layer having the amine groups in step (c) are ligand-substituted with said amine groups,
wherein said polymer is a dendrimer,
wherein said dendrimer is a generation 3 or 4 dendrimer,
wherein said amine groups are positioned at branch terminus of the dendrimer,
and
wherein the quantum dots are bonded to said amine groups of the dendrimer by ligand substitution.

8. The method according to claim 7 , wherein the quantum dot light emitting layer and the electron transport layer are formed by solution processing.

9. The method according to claim 7 , wherein the dendrimer is a polyamidoamine dendrimer.

10. The method according to claim 7 , wherein the quantum dot light emitting layer has a multilayer structure consisting of 1 to 10 layers.

Assignees

• Univ Korea Res & Bus Found
• Korea Inst Sci & Tech

Inventors

• Cho Jinhan
• Bae Wan Ki
• Cho Ikjun

Classifications

• H10K50/115

  comprising active inorganic nanostructures, e.g. luminescent quantum dots · CPC title

• H05B33/14 Primary

  characterised by the chemical or physical composition or the arrangement of the electroluminescent material {, or by the simultaneous addition of the electroluminescent material in or onto the light source} · CPC title

• H10F77/1433

  Quantum dots · CPC title

• H10H20/812

  within the light-emitting regions, e.g. having quantum confinement structures · CPC title

• H10H20/811 Primary

  having quantum effect structures or superlattices, e.g. tunnel junctions · CPC title