Light-emitting element, light-emitting device, and electronic device

• US 8,247,804 B2
• Filed: 05/13/2009
• Issued: 08/21/2012
• Est. Priority Date: 05/16/2008
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Seo, Satoshi, Ohsawa, Nobuharu
• Primary Examiner(s): Sefer, A.
• Application Number:
  US12/465,317
• Publication Number:
  US 20090283757A1
• Time in Patent Office: 1,196 Days
• Field of Search: 257/40, 257/98
• US Class Current: 257/40
• CPC Class Codes: H10K 50/155 comprising dopants
• CPC Class Codes: H10K 50/165 comprising dopants
• CPC Class Codes: H10K 50/17 Carrier injection layers
• CPC Class Codes: H10K 50/171 Electron injection layers
• CPC Class Codes: H10K 50/805 Electrodes
• 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

Abstract

Disclosed is a light-emitting element with a good carrier balance and manufacturing method thereof which does not require the formation of the heterostructure. The light-emitting element includes an organic compound film containing a first organic compound as the main component (base material) between an anode and a cathode, wherein the organic compound film is provided in contact with the anode and with the cathode. The first organic compound further includes a light-emitting region to which a light-emitting substance is added and includes a hole-transport region to which a hole-trapping substance is added and/or an electron-transport region to which an electron-trapping substance is added. The hole-transport region is located between the light-emitting region and the anode, and the electron-transport region is located between the light-emitting region and the cathode.

Claims

1. A light-emitting element comprising:

an anode;

a first layer over and in contact with the anode, the first layer comprising a first organic compound;

an organic compound layer over and in contact with the first layer;

a second layer over and in contact with the organic compound layer, the second layer comprising the first organic compound; and

a cathode over and in contact with the second layer,

wherein;

the organic compound layer comprises a first region, a light-emitting region over and in contact with the first region, and a second region over and in contact with the light-emitting region;

the first region comprises the first organic compound and a hole-trapping substance;

the light-emitting region comprises the first organic compound and a light-emitting substance; and

the second region comprises the first organic compound and an electron-trapping substance.

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

wherein the light-emitting substance is a phosphorescent compound.

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

wherein a HOMO level of the hole-trapping substance is higher than a HOMO level of the first organic compound by 0.2 eV or more.

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

wherein a LUMO level of the electron-trapping substance is lower than a LUMO level of the first organic compound by 0.2 eV or more.

5. A lighting apparatus comprising a light-emitting element, the light-emitting element comprising:

an anode;

a first layer over and in contact with the anode, the first layer comprising a first organic compound;

an organic compound layer over and in contact with the first layer;

a second layer over and in contact with the organic compound layer, the second layer comprising the first organic compound; and

a cathode over and in contact with the second layer,

wherein;

the organic compound layer comprises a first region, a light-emitting region over and in contact with the first region, and a second region over and in contact with the light-emitting region;

the first region comprises the first organic compound and a hole-trapping substance;

the light-emitting region comprises the first organic compound and a light-emitting substance; and

the second region comprises the first organic compound and an electron-trapping substance.

6. The lighting apparatus according to claim 5,

wherein the light-emitting substance is a phosphorescent compound.

7. The lighting apparatus according to claim 5,

wherein a HOMO level of the hole-trapping substance is higher than a HOMO level of the first organic compound by 0.2 eV or more.

8. The lighting apparatus according to claim 5,

wherein a LUMO level of the electron-trapping substance is lower than a LUMO level of the first organic compound by 0.2 eV or more.

9. A light-emitting element comprising:

an anode;

a first layer over and in contact with the anode, the first layer comprising a first organic compound;

an organic compound layer over and in contact with the first layer;

a second layer over and in contact with the organic compound layer, the second layer comprising the first organic compound; and

a cathode over and in contact with the second layer,

wherein;

the organic compound layer comprises a first region, a light-emitting region over and in contact with the first region, and a second region over and in contact with the light-emitting region;

the first region comprises the first organic compound and a hole-trapping substance;

the light-emitting region comprises the first organic compound and a light-emitting substance;

the second region comprises the first organic compound and an electron-trapping substance; and

the first organic compound is an anthracene derivative.

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

wherein the light-emitting substance is a phosphorescent compound.

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

wherein a HOMO level of the hole-trapping substance is higher than a HOMO level of the first organic compound by 0.2 eV or more.

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

wherein a LUMO level of the electron-trapping substance is lower than a LUMO level of the first organic compound by 0.2 eV or more.

13. A lighting apparatus comprising a light-emitting element, the light-emitting element comprising:

an anode;

a first layer over and in contact with the anode, the first layer comprising a first organic compound;

an organic compound layer over and in contact with the first layer;

a second layer over and in contact with the organic compound layer, the second layer comprising the first organic compound; and

a cathode over and in contact with the second layer,

wherein;

the organic compound layer comprises a first region, a light-emitting region over and in contact with the first region, and a second region over and in contact with the light-emitting region;

the first region comprises the first organic compound and a hole-trapping substance;

the light-emitting region comprises the first organic compound and a light-emitting substance;

the second region comprises the first organic compound and an electron-trapping substance;

the first organic compound is an anthracene derivative.

14. The lighting apparatus according to claim 13,

wherein the light-emitting substance is a phosphorescent compound.

15. The lighting apparatus according to claim 13,

wherein a HOMO level of the hole-trapping substance is higher than a HOMO level of the first organic compound by 0.2 eV or more.

16. The lighting apparatus according to claim 13,

wherein a LUMO level of the electron-trapping substance is lower than a LUMO level of the first organic compound by 0.2 eV or more.