Light-emitting element and display device

Patent metadata

Field	Value
Publication number	US-12289944-B2
Application number	US-201917637249-A
Country	US
Kind code	B2
Filing date	Sep 2, 2019
Priority date	Sep 2, 2019
Publication date	Apr 29, 2025
Grant date	Apr 29, 2025

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.

First claim

The invention claimed is:

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 with 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, and
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 and a distance between nearest quantum dots of the quantum dots in the light-emitting layer gradually changes from a side of the electron transport layer to a side of the hole transport layer.

2. 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.

3. 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 the second area.

4. The light-emitting element according to claim 3 , wherein
the first area occupies at least half of a thickness of the light-emitting layer on the electron transport layer side,
the second area occupies at least less than half of 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.

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

6. The light-emitting element according to claim 1 , wherein those ligands which are coordinated with 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.

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

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

9. The light-emitting element according to claim 8 , wherein the metal chalcogenide compound contains any of Sn 2 S 6 , Sn 2 Se 6 , In 2 Se 4 , In 2 Se 4 , In 2 Te 3 , Ga 2 Se 3 , CuInSe 2 , Cu 7 S 4 , Hg 3 Se 4 , Sb 2 Te 3 , and ZnTe.

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

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

12. The light-emitting element according to claim 1 , wherein
the light-emitting layer is a single layer, and
a thickness of the light-emitting layer is substantially uniform.

13. The light-emitting element according to claim 1 , wherein
the light-emitting layer is a single layer, and
a shape of the light-emitting layer is substantially uniform.

Assignees

• Sharp Kk

Inventors

• Honda Daisuke
• Ueta Yoshihiro

Classifications

• H10K2102/331

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

• H10K59/12

  Active-matrix OLED [AMOLED] displays · CPC title

• H10K50/16

  Electron transporting layers · CPC title

• H10K50/15

  Hole transporting layers · CPC title

• H10K50/125 Primary

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