IP Library › Granted Patent US 12,382,779
Granted Patent B2
US 12,382,779 · App. 18/672,109 · Granted Aug 5, 2025

Light-emitting element, display device, electronic device, and lighting device

Inventors: Satoshi Seo (Kanagawa, JP); Nobuharu Ohsawa (Kanagawa, JP); Shunsuke Hosoumi (Kanagawa, JP); Takahiro Ishisone (Kanagawa, JP)
Assignee: Semiconductor Energy Laboratory Co., Ltd.
H10K50/11H10K2101/10H10K2101/30
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Quick Facts
Patent No.
US 12,382,779
App. No.
18/672,109
Granted
Aug 5, 2025
Kind
B2
Abstract

A light-emitting element having high emission efficiency which includes a fluorescent material as a light-emitting substance is provided. A light-emitting element includes a pair of electrodes and an EL layer between the pair of electrodes. The EL layer includes a light-emitting layer. The light-emitting layer includes a host material and a guest material. The host material has a difference of more than 0 eV and less than or equal to 0.2 eV between a singlet excitation energy level and a triplet excitation energy level. The guest material is capable of emitting fluorescence. The triplet excitation energy level of the host material is higher than a triplet excitation energy level of the guest material.

Claims (60)

1. A light-emitting element comprising:

a pair of electrodes; and

an electroluminescence layer between the pair of electrodes,

wherein the electroluminescence layer comprises a light-emitting layer,

wherein the light-emitting layer comprises a first material and a second material,

wherein the first material comprises a condensed heterocyclic skeleton having a pyrimidine skeleton,

wherein the second material emits fluorescence,

wherein light emitted from the light-emitting layer comprises a prompt fluorescent component defined as a component during voltage application and a delayed fluorescent component defined as a component at 8 μs to 45 μs after voltage application in a transient EL measurement,

wherein a triplet excitation energy level of the first material is higher than a triplet excitation energy level of the second material,

wherein the first material exhibits thermally activated delayed fluorescence at room temperature,

wherein a singlet excitation energy level of the first material is higher than a singlet excitation energy level of the second material, and

wherein an emission spectrum of the first material comprises a region overlapping with an absorption band on the longest wavelength side in an absorption spectrum of the second material.

2. The light-emitting element according to claim 1 , wherein a difference between the singlet excitation energy level and the triplet excitation energy level of the first material is more than 0 eV and less than or equal to 0.2 eV.

3. The light-emitting element according to claim 1 ,

wherein the first material is a host material, and

wherein the second material is a guest material.

4. The light-emitting element according to claim 1 , wherein a weight ratio of the second material to the first material is more than 0 and less than or equal to 0.05.

5. The light-emitting element according to claim 1 , wherein the second material is not capable of exhibiting delayed fluorescence.

6. The light-emitting element according to claim 1 , wherein a difference between the singlet excitation energy level and the triplet excitation energy level in the second material is more than 0.2 eV.

7. The light-emitting element according to claim 1 , wherein the second material comprises any one of an anthracene skeleton or a pyrene skeleton.

8. A display device comprising:

the light-emitting element according to claim 1 ; and

a color filter overlapping with the light-emitting element.

9. An electronic device comprising:

the display device according to claim 8 ; and

a housing or a touch sensor.

10. A lighting device comprising:

the light-emitting element according to claim 1 ; and

a housing or a touch sensor.

11. A light-emitting element comprising:

a pair of electrodes; and

an electroluminescence layer between the pair of electrodes,

wherein the electroluminescence layer comprises a light-emitting layer,

wherein the light-emitting layer comprises a first organic compound, a second organic compound and a third organic compound,

wherein the first organic compound comprises a condensed heterocyclic skeleton having a pyrimidine skeleton,

wherein a combination of the first organic compound and the second organic compound forms an exciplex,

wherein the third organic compound emits fluorescence,

wherein light emitted from the light-emitting layer comprises a prompt fluorescent component defined as a component during voltage application and a delayed fluorescent component defined as a component at 8 μs to 45 μs after voltage application in a transient EL measurement,

wherein a triplet excitation energy level of the exciplex is higher than a triplet excitation energy level of the third organic compound,

wherein the exciplex exhibits thermally activated delayed fluorescence at room temperature, and

wherein a singlet excitation energy level of the exciplex is higher than a singlet excitation energy level of the third organic compound.

12. The light-emitting element according to claim 11 , wherein a difference between the singlet excitation energy level and the triplet excitation energy level of the exciplex is more than 0 eV and less than or equal to 0.2 eV.

13. The light-emitting element according to claim 11 , wherein a triplet excitation energy level of each of the first organic compound and the second organic compound is higher than the triplet excitation energy level of the exciplex.

14. The light-emitting element according to claim 11 , wherein an emission spectrum of the exciplex comprises a region overlapping with an absorption band on the longest wavelength side in an absorption spectrum of the third organic compound.

15. The light-emitting element according to claim 11 , wherein the third organic compound is a guest material.

16. The light-emitting element according to claim 11 , wherein a weight ratio of the third organic compound to the combination of the first organic compound and the second organic compound is more than 0 and less than or equal to 0.05.

17. The light-emitting element according to claim 11 , wherein the third organic compound is not capable of exhibiting delayed fluorescence.

18. The light-emitting element according to claim 11 , wherein a difference between the singlet excitation energy level and the triplet excitation energy level in the third organic compound is more than 0.2 eV.

19. The light-emitting element according to claim 11 , wherein the third organic compound comprises any one of an anthracene skeleton or a pyrene skeleton.

20. The light-emitting element according to claim 11 , wherein the second organic compound comprises an aromatic amine skeleton and carbazole skeleton.

21. The light-emitting element according to claim 20 , wherein the aromatic amine skeleton is bonded to 9-position of the carbazole skeleton.

22. A display device comprising:

the light-emitting element according to claim 11 ; and

a color filter.

23. An electronic device comprising:

the display device according to claim 22 ; and

a housing or a touch sensor.

24. A lighting device comprising:

the light-emitting element according to claim 11 ; and

a housing or a touch sensor.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded May 23, 2024
From: SEO, SATOSHI; OHSAWA, NOBUHARU; HOSOUMI, SHUNSUKE; ISHISONE, TAKAHIRO
To: SEMICONDUCTOR ENERGY LABORATORY CO., LTD.
Reel/Frame 067503/0540 →
Priority Claims (3)
JP 2014-175163 · Aug 29, 2014 · national
JP 2014-240985 · Nov 28, 2014 · national
JP 2015-108786 · May 28, 2015 · national
Continuity (6)
Continuation 18100054 · Jan 23, 2023
Continuation 16923526 · Jul 8, 2020
Continuation 16513869 · Jul 17, 2019
Continuation 15874950 · Jan 19, 2018
Continuation 14837083 · Aug 27, 2015
Related Publication 20240357845A1 · Oct 24, 2024
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