Light-Emitting Element, Light-Emitting Device, and Electronic Device

• US 20090206732A1
• Filed: 07/03/2006
• Published: 08/20/2009
• Est. Priority Date: 07/06/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Seo, Satoshi, Iwaki, Yuji
• Granted Patent: US 8,415,878 B2
• Time in Patent Office: Days
• US Class Current: 313/504
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: C09K 2211/1007 Non-condensed systems
• CPC Class Codes: C09K 2211/1014 bridged by heteroatoms, e.g. N, P, Si or B
• CPC Class Codes: C09K 2211/1022 bridged by heteroatoms, e.g. N, P, Si or B
• CPC Class Codes: C09K 2211/1029 containing one nitrogen atom as the heteroatom
• CPC Class Codes: C09K 2211/1044 containing two nitrogen atoms as heteroatoms
• CPC Class Codes: C09K 2211/1059 containing three nitrogen atoms as heteroatoms
• CPC Class Codes: C09K 2211/185 of the platinum group, i.e. Os, Ir, Pt, Ru, Rh or Pd
• CPC Class Codes: H05B 33/12 Light sources with substantially two-dimensional radiating surfaces
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/14 Carrier transporting layers
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass
• CPC Class Codes: H10K 85/342 comprising iridium
• CPC Class Codes: H10K 85/636 comprising heteroaromatic hydrocarbons as substituents on the nitrogen atom

Abstract

It is an object to provide a light-emitting element which can reduce power consumption. A light-emitting element is provided, which includes a pair of electrodes and a light-emitting layer interposed between the pair of electrodes. The light-emitting layer includes at least a first layer and a second layer, each of the first layer and the second layer includes an emission center and a host material, the emission center is dispersed in the host material, a thickness of each of the first layer and the second layer is 1 nm or more and 10 nm or less, and the first layer is not in contact with the second layer.

Claims

1. A light-emitting element comprising:

a pair of electrodes; and

a light-emitting layer interposed between the pair of electrodes, wherein;

the light-emitting layer includes at least a first layer and a second layer, each of the first layer and the second layer includes an emission center and a host material, the emission center is dispersed in the host material,

a thickness of each of the first layer and the second layer is 1 nm or more and 10 nm or less, and

the first layer is not in contact with the second layer.

6. The light-emitting element according to any one of claims 1 to 4, wherein an absolute value of reduction potential of the emission center is smaller than that of reduction potential of the host material.

7. The light-emitting element according to any one of claims 1 to 4, wherein electron affinity of the emission center is larger than that of the host material.

8. The light-emitting element according to any one of claims 1 to 4, wherein the emission center is an organic material.

9. The light-emitting element according to any one of claims 1 to 4, wherein the emission center is a phosphorescent material.

10. The light-emitting element according to any one of claims 1 to 4, wherein the emission center includes an electron withdrawing group.

11. The light-emitting element according to any one of claims 1 to 4, wherein the emission center is a phosphorescent material having an electron withdrawing group.

12. The light-emitting element according to any one of claims 1 to 4, wherein the emission center is contained at 0.001 to 50 wt % with respect to the host material.

13. The light-emitting element according to any one of claims 1 to 4, wherein the emission center is (acetylacetonate)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III).

14. The light-emitting element according to any one of claims 1 to 4, wherein the emission center is (acetylacetonate)bis[2,3-bis(4-fluorophenyl)-5-methylpyrazinato]iridium(III).

15. The light-emitting element according to any one of claims 1 to 4, wherein the host material is an organic material.

16. The light-emitting element according to any one of claims 1 to 4, wherein the host material is 4,4′

-di(N-carbazolyl)biphenyl.

17. The light-emitting element according to any one of claims 1 to 4, further comprises a carrier transporting layer, wherein

the light-emitting layer includes a fourth layer in contact with the carrier transporting layer,

a thickness of the fourth layer is 1 nm or more and 10 nm or less,

the fourth layer includes a material having a carrier transporting property, and

a band gap of the material having a carrier transporting property is bigger than that of a material included in the carrier transporting layer.

18. A light-emitting device using the light-emitting element according to any one of claims 1 to 4 as a pixel or a light source.

19. An electronic device using the light-emitting element according to any one of claims 1 to 4 as a display portion or a light source.

2. A light-emitting element comprising:

a pair of electrodes; and

a light-emitting layer interposed between the pair of electrodes, wherein;

the light-emitting layer includes at least a first layer and a second layer, each of the first layer and the second layer includes an emission center and a host material, the emission center is dispersed in the host material,

a thickness of each of the first layer and the second layer is 1 nm or more and 10 nm or less,

the first layer is not in contact with the second layer, and

the distance between the first layer and the second layer is 1 nm or more and 10 nm or less.

3. A light-emitting element comprising:

a pair of electrodes; and

a light-emitting layer interposed between the pair of electrodes, wherein;

the light-emitting layer includes at least a first layer, a second layer, and a third layer,

each of the first layer and the second layer includes an emission center and a host material, the emission center is dispersed in the host material,

a thickness of each of the first layer and the second layer is 1 nm or more and 10 nm or less, and

the third layer is interposed between the first layer and the second layer.

5. The light-emitting element according to claim 3 or 4, wherein the third layer contains the host material.

4. A light-emitting element comprising:

a pair of electrodes; and

a light-emitting layer interposed between the pair of electrodes, wherein;

the light-emitting layer includes at least a first layer, a second layer, and a third layer,

each of the first layer and the second layer includes an emission center and a host material, the emission center is dispersed in the host material,

a thickness of each of the first layer, the second layer, and the third layer is 1 nm or more and 10 nm or less, and

the third layer is interposed between the first layer and the second layer.