Light-emitting element, light-emitting device, and method for manufacturing light-emitting element

Patent metadata

Field	Value
Publication number	US-12108617-B2
Application number	US-201917640127-A
Country	US
Kind code	B2
Filing date	Sep 4, 2019
Priority date	Sep 4, 2019
Publication date	Oct 1, 2024
Grant date	Oct 1, 2024

Abstract

A light-emitting layer of a light-emitting element contains halogen ligands and organic ligands coordinated to each of quantum dots. The light-emitting layer includes: a first region toward a hole-transport layer; and a second region toward an electron-transport layer. In the first region, a concentration of the halogen ligands is higher than a concentration of the organic ligands, and, in the second region, the concentration of the halogen ligands is lower than the concentration of the organic ligands.

First claim

The invention claimed is:

1. A light-emitting element comprising:
a cathode; an anode; a light-emitting layer provided between the cathode and the anode and containing quantum dots; an electron-transport layer provided between the light-emitting layer and the cathode; and a hole-transport layer provided between the light-emitting layer and the anode,
the light-emitting layer containing halogen ligands and organic ligands coordinated to each of the quantum dots,
the light-emitting layer including: a first region toward the hole-transport layer; and a second region toward the electron-transport layer, and
in the first region, a concentration of the halogen ligands being higher than a concentration of the organic ligands, and, in the second region, the concentration of the halogen ligands being lower than the concentration of the organic ligands.

2. The light-emitting element according to claim 1 , wherein
the halogen ligands contain halogens selected from among at least one or more of F, Cl, Br and I.

3. The light-emitting element according to claim 1 , wherein
of ligands coordinated to the quantum dots contained in the first region, a proportion of the halogen ligands is higher than a proportion of the organic ligands.

4. The light-emitting element according to claim 1 , wherein
of ligands coordinated to the quantum dots contained in the second region, a proportion of the organic ligands is higher than a proportion of the halogen ligands.

5. The light-emitting element according to claim 1 , wherein
the light-emitting layer contains quantum dots provided between the hole-transport layer and the first region, and having the halogen ligands alone.

6. The light-emitting element according to claim 1 , wherein
the light-emitting layer contains quantum dots provided between the electron-transport layer and the second region, and having the organic ligands alone.

7. The light-emitting element according to claim 1 , wherein
the organic ligands contained in the first region are smaller in quantity than the organic ligands contained in the second region.

8. The light-emitting element according to claim 1 , wherein
in the light-emitting layer, a concentration of halogens gradually decreases from toward the hole-transport layer to toward the electron-transport layer.

9. The light-emitting element according to claim 1 , wherein
the light-emitting layer includes: a red light-emitting layer; and a green light-emitting layer, and
in a thickness direction of the light-emitting layer, a proportion of the first region in the green light-emitting layer is larger than a proportion of the first region in the red light-emitting layer.

10. The light-emitting element according to claim 9 , wherein
the first region in the green light-emitting layer is thicker than the first region in the red light-emitting layer.

11. The light-emitting element according to claim 9 , wherein
the light-emitting layer further includes a blue light-emitting layer, and
in the thickness direction of the light-emitting layer, the proportion of the first region in the green light-emitting layer is smaller than a proportion of the first region in the blue light-emitting layer.

12. The light-emitting element according to claim 11 , wherein
the first region in the blue light-emitting layer is thicker than the first region in the red light-emitting layer.

13. The light-emitting element according to claim 11 , wherein
the first region in the blue light-emitting layer is thicker than the first region in the green light-emitting layer.

14. The light-emitting element according to claim 9 , wherein
a thickness of the first region in the red light-emitting layer is greater than or equal to one-fifth of, and smaller than or equal to one-third of, a thickness of the red light-emitting layer.

15. The light-emitting element according to claim 9 , wherein
a thickness of the first region in the green light-emitting layer is greater than or equal to one-fourth of, and smaller than or equal to three-fourth of, a thickness of the green light-emitting layer.

16. The light-emitting element according to claim 11 , wherein
a thickness of the first region in the blue light-emitting layer is greater than or equal to one-half of, and smaller than or equal to four-fifth of, a thickness of the blue light-emitting layer.

17. The light-emitting element according to claim 1 , wherein
the light-emitting layer includes: a red light-emitting layer; and a green light-emitting layer, and
a proportion of a thickness of the first region in the red light-emitting layer to a thickness of the red light-emitting layer is equal to a proportion of a thickness of the first region in the green light-emitting layer to a thickness of the green light-emitting layer, and the thicknesses of the first regions in the red light-emitting layer and in the green light-emitting layer are greater than or equal to one-fifth of, and smaller than or equal to one-half of, the thicknesses of the red light-emitting layer and the green light-emitting layer, and
the concentration of the halogen ligands in the first region of the green light-emitting layer is higher than the concentration of the halogen ligands in the first region of the red light-emitting layer.

18. The light-emitting element according to claim 17 , wherein
the light-emitting layer further includes a blue light-emitting layer, and
a proportion of the thickness of the first region in the green light-emitting layer to the thickness of the green light-emitting layer is equal to a proportion of a thickness of the first region in the blue light-emitting layer to a thickness of the blue light-emitting layer, and the thicknesses of the first regions in the green light-emitting layer and in the blue light-emitting layer are greater than or equal to one-fifth of, and smaller than or equal to one-half of, the thicknesses of the green light-emitting layer and the blue light-emitting layer, and
the concentration of the halogen ligands in the first region of the blue light-emitting layer is higher than the concentration of the halogen ligands in the first region of the green light-emitting layer.

19. A light-emitting device including at least one light-emitting element according to claim 1 .

20. A method for manufacturing a light-emitting element including: a cathode; an anode; a light-emitting layer provided between the cathode and the anode and containing quantum dots; an electron-transport layer provided between the light-emitting layer and the cathode; and a hole-transport layer provided between the light-emitting layer and the anode, the method comprising
forming the light-emitting layer above the electron-transport layer,
the forming of the light-emitting layer including:
stacking the light-emitting layer above the electron-transport layer, the light-emitting layer containing the quantum dots having organic ligands;
impregnating a surface of the light-emitting layer with a halogen agent toward the electron-transport layer; and
heating the light-emitting layer after the impregnating.

Assignees

• Sharp Kk

Inventors

• Honda Daisuke
• Ueta Yoshihiro

Classifications

• H10K71/40

  Thermal treatment, e.g. annealing in the presence of a solvent vapour · CPC title

• H10K50/125 Primary

  specially adapted for multicolour light emission, e.g. for emitting white light · CPC title

• H10K59/35 Primary

  comprising red-green-blue [RGB] subpixels · CPC title

• H10K2102/331

  Nanoparticles used in non-emissive layers, e.g. in packaging layer · CPC title

• H10K71/00

  Manufacture or treatment specially adapted for the organic devices covered by this subclass · CPC title