Light emitting element and light emitting device

• US 7,940,002 B2
• Filed: 09/21/2009
• Issued: 05/10/2011
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Abe, Hiroko, Seo, Satoshi, Kumaki, Daisuke, Ikeda, Hisao
• Primary Examiner(s): Patel; Nimeshkumar D
• Assistant Examiner(s): Bowman; Mary Ellen
• Application Number:
  US12/563,242
• Publication Number:
  US 20100033090A1
• Time in Patent Office: 596 Days
• Field of Search: 313500-512, 428/690
• 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 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• 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 light emitting element comprising:

n pieces of light emitting layers between a first electrode and a second electrode, wherein n is a natural number larger than 1; and

a stacked layer provided between the m^th light emitting layer and the m+1^th light emitting layer, wherein m is a natural number equal to or larger than 1 and smaller than n,

wherein the stacked layer comprises a first layer and a second layer which are in contact with each other,

wherein the first layer contains both molybdenum oxide and a substance that transports a hole easily, and

wherein the second layer contains both a first substance that transports an electron easily and a second substance that has an electron donating property with respect to the first substance.

2. The light emitting element according to claim 1,

wherein the substance that transports a hole easily is selected from an aromatic amine.

3. The light emitting element according to claim 1,

wherein the second substance is a metal complex.

4. The light emitting element according to claim 1,

wherein the light emitting element is arranged to emit white light.

5. The light emitting element according to claim 1,

wherein each of the n pieces of light emitting layers further comprises a hole transporting layer and an electron transporting layer.

6. A light emitting element comprising:

a first light emitting layer and a second light emitting layer which are provided between a first electrode and a second electrode; and

a stacked layer provided between the first light emitting layer and the second light emitting layer,

wherein the stacked layer comprises a first layer and a second layer which are in contact with each other,

wherein the first layer contains both molybdenum oxide and a substance that transports a hole easily, and

wherein the second layer contains both a first substance that transports an electron easily and a second substance that has an electron donating property with respect to the first substance.

7. The light emitting element according to claim 6,

wherein the substance that transports a hole easily is selected from an aromatic amine.

8. The light emitting element according to claim 6,

wherein the second substance is a metal complex.

9. The light emitting element according to claim 6,

wherein the light emitting element is arranged to emit white light.

10. The light emitting element according to claim 6,

wherein each of the n pieces of light emitting layers further comprises a hole transporting layer and an electron transporting layer.

11. The light emitting element according to claim 6,

wherein an emission color of the first light emitting layer and an emission color of the second light emitting layer are complementary to each other.

12. A light emitting element comprising:

a first light emitting layer formed over a first electrode;

a first stacked layer formed over the first light emitting layer;

a second light emitting layer formed over the first stacked layer;

a second stacked layer formed over the second light emitting layer;

a third light emitting layer formed over the second stacked layer;

a second electrode formed over the third light emitting layer,

wherein the first stacked layer and the second stacked layer each comprise a first layer and a second layer which are in contact with each other,

wherein the first layer contains both molybdenum oxide and a substance that transports a hole easily, and

wherein the second layer contains both a first substance that transports an electron easily and a second substance that has an electron donating property with respect to the first substance.

13. The light emitting element according to claim 12,

wherein the substance that transports a hole easily is selected from an aromatic amine.

14. The light emitting element according to claim 12,

wherein the second substance is a metal complex.

15. The light emitting element according to claim 12,

wherein the light emitting element is arranged to emit white light.

16. The light emitting element according to claim 12,

wherein each of the n pieces of light emitting layers further comprises a hole transporting layer and an electron transporting layer.

17. The light emitting element according to claim 12,

wherein the first light emitting layer, the second light emitting layer, and the third emitting layer emit blue light, green light, and red light, respectively.

18. A lighting appliance having a light emitting element, the light emitting element comprising:

n pieces of light emitting layers between a first electrode and a second electrode, wherein n is a natural number larger than 1; and

a stacked layer provided between the m^th light emitting layer and the m+1^th light emitting layer, wherein m is a natural number equal to or larger than 1 and smaller than n,

wherein the stacked layer comprises a first layer and a second layer which are in contact with each other,

wherein the first layer contains both molybdenum oxide and a substance that transports a hole easily, and

wherein the second layer contains both a first substance that transports an electron easily and a second substance that has an electron donating property with respect to the first substance.

19. The lighting appliance according to claim 18,

wherein the substance that transports a hole easily is selected from an aromatic amine.

20. The lighting appliance according to claim 18,

wherein the second substance is a metal complex.

21. The lighting appliance according to claim 18,

wherein the light emitting element is arranged to emit white light.

22. The lighting appliance according to claim 18,

wherein each of the n pieces of light emitting layers further comprises a hole transporting layer and an electron transporting layer.

23. A lighting appliance having a light emitting element, the light emitting element comprising:

a first light emitting layer and a second light emitting layer which are provided between a first electrode and a second electrode; and

a stacked layer provided between the first light emitting layer and the second light emitting layer,

wherein the stacked layer comprises a first layer and a second layer which are in contact with each other,

wherein the first layer contains both molybdenum oxide and a substance that transports a hole easily, and

wherein the second layer contains both a first substance that transports an electron easily and a second substance that has an electron donating property with respect to the first substance.

24. The lighting appliance according to claim 23,

wherein the substance that transports a hole easily is selected from an aromatic amine.

25. The lighting appliance according to claim 23,

wherein the second substance is a metal complex.

26. The lighting appliance according to claim 23,

wherein the light emitting element is arranged to emit white light.

27. The lighting appliance according to claim 23,

wherein each of the n pieces of light emitting layers further comprises a hole transporting layer and an electron transporting layer.

28. The lighting appliance according to claim 23,

wherein an emission color of the first light emitting layer and an emission color of the second light emitting layer are complementary to each other.

29. A lighting appliance having a light emitting element, the light emitting element comprising:

a first light emitting layer formed over a first electrode;

a first stacked layer formed over the first light emitting layer;

a second light emitting layer formed over the first stacked layer;

a second stacked layer formed over the second light emitting layer;

a third light emitting layer formed over the second stacked layer;

a second electrode formed over the third light emitting layer,

wherein the first stacked layer and the second stacked layer each comprise a first layer and a second layer which are in contact with each other,

wherein the first layer contains both molybdenum oxide and a substance that transports a hole easily, and

wherein the second layer contains both a first substance that transports an electron easily and a second substance that has an electron donating property with respect to the first substance.

30. The lighting appliance according to claim 29,

wherein the substance that transports a hole easily is selected from an aromatic amine.

31. The lighting appliance according to claim 29,

wherein the second substance is a metal complex.

32. The lighting appliance according to claim 29,

wherein the light emitting element is arranged to emit white light.

33. The lighting appliance according to claim 29,

wherein each of the n pieces of light emitting layers further comprises a hole transporting layer and an electron transporting layer.

34. The lighting appliance according to claim 29,

wherein the first light emitting layer, the second light emitting layer, and the third emitting layer emit blue light, green light, and red light, respectively.