Granted Patent B2

US 12,289,944 · App. 17/637,249 · Granted Apr 29, 2025

Inventors: Daisuke Honda (Sakai, JP); Yoshihiro Ueta (Sakai, JP)

Assignee: SHARP KABUSHIKI KAISHA

H10K50/125H10K50/15H10K50/16H10K59/12H10K2102/331

Abstract

Claims (31)

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.

Assignments (1)

Continuity (1)

References Cited (17)