Light emitting element and light emitting device

• US 8,344,621 B2
• Filed: 05/05/2011
• Issued: 01/01/2013
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kumaki, Daisuke, Ikeda, Hisao, Abe, Hiroko, Seo, Satoshi
• Primary Examiner(s): Bowman, Mary Ellen
• Application Number:
  US13/101,572
• Publication Number:
  US 20110272690A1
• Time in Patent Office: 607 Days
• Field of Search: 313/504, 313/506, 313/498, 428/690, 252/301.6 S
• US Class Current: 313/506
• CPC Class Codes: H10K 50/14 Carrier transporting layers
• CPC Class Codes: H10K 50/155 comprising dopants
• CPC Class Codes: H10K 50/165 comprising dopants
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 50/84 Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 59/10 OLED displays
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/87 Passivation; Containers; Encapsulations
• CPC Class Codes: Y10S 428/917 Electroluminescent
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

A light emitting element of the invention includes n pieces of light emitting layers (n is a natural number) between first and second electrodes. A first layer and a second layer are provided between the m^th light emitting layer (m is a natural number of 1≦m≦n) and the m+1^th light emitting layer. The first and second layers are contacted to each other. The first layer contain a substance that transports holes easily and a substance with an electron accepting property. The second layer contains a substance that transports electrons easily and a substance with an electron donating property. Molybdenum oxide is used as the substance with the electron accepting property.

Claims

1. A lighting appliance comprising:

an anode;

a first light-emitting layer over the anode;

a first layer over the first light-emitting layer, the first layer comprising an electron-transporting material as a first substance and an electron donating material as a second substance with respect to the electron-transporting material;

a second layer over and in contact with the first layer, the second layer comprising molybdenum oxide;

a second light-emitting layer over the second layer; and

a cathode over the second layer.

2. The lighting appliance according to claim 1,

wherein the second layer further comprises a hole-transporting material.

3. The lighting appliance according to claim 2,

wherein the hole-transporting material is an aromatic amine.

4. The lighting appliance according to claim 1,

wherein the electron-transporting material is a metal complex having a quinoline ligand or a benzoquinoline ligand.

5. The lighting appliance according to claim 1,

wherein the electron donating material is selected from an alkali metal, an alkali earth metal, an oxide of the alkali metal, an oxide of the alkali earth metal, a nitride of the alkali metal, and a nitride of the alkali earth metal.

6. The lighting appliance according to claim 1,

wherein a color of light emitted from the first light-emitting layer and a color of light emitted from the second light-emitting layer are complementary to each other.

7. The lighting appliance according to claim 1,

wherein the anode is able to reflect light emitted from the first light-emitting layer and light emitted from the second light-emitting layer.

8. A lighting appliance comprising:

an anode;

a first layer over and in contact with the anode, the first layer comprising molybdenum oxide;

a first light-emitting layer over the first layer;

a second layer over the first light-emitting layer, the second layer comprising an electron-transporting material as a first substance and an electron donating material as a second substance with respect to the electron-transporting material;

a third layer over and in contact with the second layer, the third layer comprising molybdenum oxide;

a second light-emitting layer over the third layer;

a fourth layer over the second light-emitting layer, the fourth layer comprising the electron-transporting material and the electron donating material; and

a cathode over the fourth layer.

9. The lighting appliance according to claim 8,

wherein the first layer further comprises a hole-transporting material.

10. The lighting appliance according to claim 9,

wherein the hole-transporting material is an aromatic amine.

11. The lighting appliance according to claim 8,

wherein the third layer further comprises a hole-transporting material.

12. The lighting appliance according to claim 11,

wherein the hole-transporting material is an aromatic amine.

13. The lighting appliance according to claim 8,

wherein the electron-transporting material is a metal complex having a quinoline ligand or a benzoquinoline ligand.

14. The lighting appliance according to claim 8,

wherein the electron donating material is selected from an alkali metal, an alkali earth metal, an oxide of the alkali metal, an oxide of the alkali earth metal, a nitride of the alkali metal, and a nitride of the alkali earth metal.

15. The lighting appliance according to claim 8,

wherein a color of light emitted from the first light-emitting layer and a color of light emitted from the second light-emitting layer are complementary to each other.

16. The lighting appliance according to claim 8,

wherein the anode is able to reflect light emitted from the first light-emitting layer and light emitted from the second light-emitting layer.

17. A lighting appliance comprising:

an anode;

a first layer over and in contact with the anode, the first layer comprising molybdenum oxide;

a first light-emitting layer over the first layer;

a second layer over the first light-emitting layer, the second layer comprising an electrontransporting material as a first substance and an electron donating material as a second substance with respect to the electron-transporting material;

a third layer over and in contact with the second layer, the third layer comprising molybdenum oxide;

a second light-emitting layer over the third layer;

a fourth layer over the second light-emitting layer, the fourth layer comprising the electron-transporting material and the electron donating material;

a fifth layer over and in contact with the fourth layer, the fifth layer comprising molybdenum oxide;

a third light-emitting layer over the fifth layer;

a sixth layer over the third light-emitting layer, the sixth layer comprising the electrontransporting material and the electron donating material; and

a cathode over the sixth layer.

18. The lighting appliance according to claim 17,

wherein the first layer further comprises a hole-transporting material.

19. The lighting appliance according to claim 18,

wherein the hole-transporting material is an aromatic amine.

20. The lighting appliance according to claim 17,

wherein the third layer further comprises a hole-transporting material.

21. The lighting appliance according to claim 20,

wherein the hole-transporting material is an aromatic amine.

22. The lighting appliance according to claim 17,

wherein the fifth layer further comprises a hole-transporting material.

23. The lighting appliance according to claim 22,

wherein the hole-transporting material is an aromatic amine.

24. The lighting appliance according to claim 17,

wherein the electron-transporting material is a metal complex having a quinoline ligand or a benzoquinoline ligand.

25. The lighting appliance according to claim 17,

wherein the electron donating material is selected from an alkali metal, an alkali earth metal, an oxide of the alkali metal, an oxide of the alkali earth metal, a nitride of the alkali metal, and a nitride of the alkali earth metal.

26. The lighting appliance according to claim 17,

wherein a color of light emitted from the first light-emitting layer, a color of light emitted from the second light-emitting layer, and a color of light emitting from the third light-emitting layer are arranged so that the lighting appliance emits white light.

27. The lighting appliance according to claim 17,

wherein the anode is able to reflect light emitted from the first light-emitting layer, light emitted from the second light-emitting layer, and light emitted from the third light-emitting layer.