Light-emitting element, light-emitting device, electronic device, lighting device, and organic compound

• US 9,985,221 B2
• Filed: 07/23/2015
• Issued: 05/29/2018
• Est. Priority Date: 07/25/2014
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Seo, Satoshi, Hamada, Takao, Takahashi, Tatsuyoshi, Kitano, Yasushi, Suzuki, Hiroki, Inoue, Hideko
• Primary Examiner(s): Clark, Gregory D
• Application Number:
  US14/807,426
• Publication Number:
  US 20160028022A1
• Time in Patent Office: 1,041 Days
• Field of Search: None
• CPC Class Codes: C07D 403/14 containing three or more hetero rings
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/633 comprising polycyclic condensed aromatic hydrocarbons as substituents on the nitrogen atom
• CPC Class Codes: H10K 85/636 comprising heteroaromatic hydrocarbons as substituents on the nitrogen atom
• CPC Class Codes: H10K 85/6572 comprising only nitrogen in the heteroaromatic polycondensed ring system, e.g. phenanthroline or carbazole
• CPC Class Codes: Y02E 10/549 Organic PV cells
• CPC Class Codes: Y02P 20/582 Recycling of unreacted starting or intermediate materials

Abstract

To provide a light-emitting element with an improved reliability, a light-emitting element with a high current efficiency (or a high quantum efficiency), and a novel dibenzo[f,h]quinoxaline derivative that is favorably used in a light-emitting element which is one embodiment of the present invention. A light-emitting element includes an EL layer between an anode and a cathode. The EL layer includes a light-emitting layer; the light-emitting layer contains a first organic compound having an electron-transport property and a hole-transport property, a second organic compound having a hole-transport property, and a light-emitting substance; the combination of the first organic compound and the second organic compound forms an exciplex; the HOMO level of the first organic compound is lower than the HOMO level of the second organic compound; and a difference between the HOMO level of the first organic compound and the HOMO level of the second organic compound is less than or equal to 0.4 eV.

Claims

1. A light-emitting element comprising:

an EL layer between an anode and a cathode,

wherein the EL layer includes a light-emitting layer,

wherein the light-emitting layer contains a first organic compound having an electron-transport property and a hole-transport property, a second organic compound having a hole-transport property, and a light-emitting substance,

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

wherein a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound, and

wherein a difference between the HOMO level of the first organic compound and the HOMO level of the second organic compound is less than or equal to 0.4 eV.

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

wherein the first organic compound includes a 6-membered nitrogen-containing heteroaromatic ring and a carbazole skeleton and does not include a triarylamine skeleton.

3. The light-emitting element according to claim 1, wherein the light-emitting substance is a phosphorescent compound.

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

wherein the EL layer includes a hole-transport layer, the hole-transport layer being in contact with the light-emitting layer and containing a third organic compound having a hole-transport property, and

wherein a HOMO level of the third organic compound is lower than the HOMO level of the second organic compound.

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

wherein the first organic compound is represented by a general formula (G0),

6. A light-emitting device comprising:

the light-emitting element according to claim 1; and

a housing.

7. An electronic device comprising:

the light-emitting device according to claim 6; and

a connection terminal or an operation key.

8. A lighting device comprising:

the light-emitting element according to claim 1; and

a housing.

9. A light-emitting element comprising:

an EL layer between an anode and a cathode,

wherein the EL layer includes a light-emitting layer,

wherein the light-emitting layer contains a first organic compound having an electron-transport property and a hole-transport property, a second organic compound having a hole-transport property, and a light-emitting substance,

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

wherein the first organic compound includes a 6-membered nitrogen-containing heteroaromatic ring and a bicarbazole skeleton and does not include a triarylamine skeleton, and

wherein the second organic compound includes a triarylamine skeleton.

10. The light-emitting element according to claim 9, wherein the bicarbazole skeleton is a 3,3′

-bicarbazole skeleton or a 2,3′

-bicarbazole skeleton.

11. The light-emitting element according to claim 9, wherein the light-emitting substance is a phosphorescent compound.

12. The light-emitting element according to claim 9,

wherein the EL layer includes a hole-transport layer, the hole-transport layer being in contact with the light-emitting layer and containing a third organic compound having a hole-transport property, and

wherein a HOMO level of the third organic compound is lower than the HOMO level of the second organic compound.

13. The light-emitting element according to claim 9,

wherein the first organic compound is represented by a general formula (G0),

14. A light-emitting device comprising:

the light-emitting element according to claim 9; and

a housing.

15. An electronic device comprising:

the light-emitting device according to claim 14; and

a connection terminal or an operation key.

16. A lighting device comprising:

the light-emitting element according to claim 9; and

a housing.