Light-emitting element including intermediate conductive layer having a hole-injection layer with an island-like structure

• US 8,018,152 B2
• Filed: 05/17/2005
• Issued: 09/13/2011
• Est. Priority Date: 05/20/2004
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Nomura, Ryoji, Abe, Hiroko, Seo, Satoshi, Yamazaki, Shunpei, Nakamura, Yasuo
• Primary Examiner(s): Hines; Anne M
• Assistant Examiner(s): GREEN, TRACIE Y
• Application Number:
  US11/587,843
• Publication Number:
  US 20070222379A1
• Time in Patent Office: 2,310 Days
• Field of Search: 313501-512, 445 24- 25
• US Class Current: 313/509
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H10K 50/17 Carrier injection layers
• CPC Class Codes: H10K 50/171 Electron injection layers
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths

Abstract

When a light-emitting element having an intermediate conductive layer between a plurality of light-emitting layers is formed, the intermediate conductive layer can have transparency; and thus, materials are largely limited and the manufacturing process of an element becomes complicated by a conventional method. A light-emitting element according to the present invention is formed by sequentially stacking a pixel electrode, a first light-emitting layer, an intermediate conductive layer (including an electron injecting layer and a hole-injecting layer, one of which is island-like), a second light-emitting layer and an opposite electrode. Therefore, the present invention can provide a light-emitting element typified by an organic EL element in which a range of choice of materials that can be used as the intermediate conductive layer is broadened extremely, and which can realize a high light-emitting efficiency, a low power consumption and a high reliability, and further a display device using the light-emitting element.

Claims

1. A light-emitting element comprising:

a first electrode;

a first light-emitting layer over the first electrode;

an intermediate conductive layer on the first light-emitting layer;

a second light-emitting layer on the intermediate conductive layer; and

a second electrode over the second light-emitting layer,

wherein the intermediate conductive layer comprises an electron-injecting layer and a hole-injecting layer that is in contact with the electron-injecting layer, and

wherein the hole-injecting layer has at least one island-like structure.

2. The light-emitting element according to claim 1, wherein the electron-injecting layer contains Mg—

Ag, Al—

Li, Mg—

Li, Ca₃N₂ or Mg₃N₂.

3. The light-emitting element according to claim 1, wherein the first electrode is a pixel electrode and the second electrode is an opposite electrode.

31. The light-emitting element according to claim 1, wherein the hole-injecting layer comprises molybdenum oxide and aromatic amine.

4. A light-emitting element comprising:

a first electrode;

a plurality of light-emitting layers;

a plurality of intermediate conductive layers sandwiched by the plurality of light-emitting layers; and

a second electrode,

wherein the first electrode, the plurality of light-emitting layers, the plurality of intermediate conductive layers sandwiched by the plurality of light-emitting layers, the second electrode are stacked,

wherein at least one of the intermediate conductive layers includes an electron-injecting layer and a hole-injecting layer that is in contact with the electron-injecting layer, and

wherein the hole-injecting layer has at least one island-like structure.

5. The light-emitting element according to claim 4, wherein the electron-injecting layer contains Mg—

Ag, Al—

Li, Mg—

Li, Ca₃N₂ or Mg₃N₂.

6. The light-emitting element according to claim 4, wherein the first electrode is a pixel electrode and the second electrode is an opposite electrode.

32. The light-emitting element according to claim 4, wherein the hole-injecting layer comprises molybdenum oxide and aromatic amine.

7. A light-emitting element comprising:

an n number of light-emitting layers (where n is an integer equal to or greater than

     2) comprising a first through an n-th light-emitting layers between a first electrode and a second electrode,

wherein an intermediate conductive layer is formed between a k-th light-emitting layer (where k is an integer of 1≦

k≦

(n−

1)) and a (k+1)th light-emitting layer,

wherein the intermediate conductive layer comprises an electron-injecting layer and a hole-injecting layer that is in contact with the electron-injecting layer,

wherein the hole-injecting layer has at least one island-like structure.

8. The light-emitting element according to claim 7, wherein the electron-injecting layer contains Mg—

Ag, Al—

Li, Mg—

Li, Ca₃N₂ or Mg₃N₂.

9. The light-emitting element according to claim 7, wherein the first electrode is a pixel electrode and the second electrode is an opposite electrode.

33. The light-emitting element according to claim 7, wherein the hole-injecting layer comprises molybdenum oxide and aromatic amine.

10. A display device having a light-emitting element comprising:

a first electrode;

a first light-emitting layer over the first electrode;

an intermediate conductive layer on the first light-emitting layer;

a second light-emitting layer on the intermediate conductive layer; and

a second electrode over the second light-emitting layer,

wherein the intermediate conductive layer comprises an electron-injecting layer and a hole-injecting layer that is in contact with the electron-injecting layer,

wherein the hole-injecting layer has at least one island-like structure, and

wherein the light-emitting element is connected to a transistor formed over a substrate through an interlayer insulating film.

11. The display device according to claim 10, wherein the electron-injecting layer contains Mg—

Ag, Al—

Li, Mg—

Li, Ca₃N₂ or Mg₃N₂.

12. The display device according to claim 10, wherein the interlayer insulating film contains carbon, and has a light-shielding property.

13. The display device according to claim 10, wherein a bank layer that contains carbon and has a light-shielding property is provided to be in contact with the light-emitting layer.

14. The display device according to claim 10, wherein the transistor and the light-emitting element are connected to each other by a wiring of an alloy containing aluminum and nickel.

15. The display device according to claim 14, wherein the alloy further contains carbon.

16. The display device according to claim 10, wherein the first electrode is a pixel electrode and the second electrode is an opposite electrode.

34. The display device according to claim 10, wherein the hole-injecting layer comprises molybdenum oxide and aromatic amine.

17. A display device having a light-emitting element comprising:

a first electrode;

a plurality of light-emitting layers;

a plurality of intermediate conductive layers sandwiched by the plurality of light-emitting layers; and

a second electrode,

wherein the first electrode, the plurality of light-emitting layers, the plurality of intermediate conductive layers sandwiched by the plurality of light-emitting layers, the second electrode are stacked,

wherein at least one of the intermediate conductive layers includes an electron-injecting layer and a hole-injecting layer that is in contact with the electron-injecting layer,

wherein the hole-injecting layer has at least one island-like structure, and

wherein the light-emitting element is connected to a transistor formed over a substrate through an interlayer insulating film.

18. The display device according to claim 17, wherein the electron-injecting layer contains Mg—

Ag, Al—

Li, Mg—

Li, Ca₃N₂ or Mg₃N₂.

19. The display device according to claim 17, wherein the interlayer insulating film contains carbon, and has a light-shielding property.

20. The display device according to claim 17, wherein a bank layer that contains carbon and has a light-shielding property is provided to be in contact with the light-emitting layer.

21. The display device according to claim 17, wherein the transistor and the light-emitting element are connected to each other by a wiring of an alloy containing aluminum and nickel.

22. The display device according to claim 21, wherein the alloy further contains carbon.

23. The display device according to claim 17, wherein the first electrode is a pixel electrode and the second electrode is an opposite electrode.

35. The display device according to claim 17, wherein the hole-injecting layer comprises molybdenum oxide and aromatic amine.

24. A display device having a light-emitting element comprising:

the light emitting element formed by sequentially laminating an n number of light-emitting layers (where n is an integer equal to or greater than

     2) comprising a first through an n-th light-emitting layers between a first electrode and a second electrode,

wherein an intermediate conductive layer is formed between a k-th light-emitting layer (where k is an integer of 1≦

k≦

(n−

1)) and a (k+1)th light-emitting layer,

wherein the intermediate conductive layer comprises an electron-injecting layer and a hole-injecting layer that is in contact with the electron-injecting layer,

wherein the hole-injecting layer has at least one island-like structure, and

wherein the light-emitting element is connected to a transistor formed over a substrate through an interlayer insulating film.

25. The display device according to claim 24, wherein the electron-injecting layer contains Mg—

Ag, Al—

Li, Mg—

Li, Ca₃N₂ or Mg₃N₂.

26. The display device according to claim 24, wherein the interlayer insulating film contains carbon, and has a light-shielding property.

27. The display device according to claim 24, wherein a bank layer that contains carbon and has a light-shielding property is provided to be in contact with the light-emitting layer.

28. The display device according to claim 24, wherein the transistor and the light-emitting element are connected to each other by a wiring of an alloy containing aluminum and nickel.

29. The display device according to claim 28, wherein the alloy further contains carbon.

30. The display device according to claim 24, wherein the first electrode is a pixel electrode and the second electrode is an opposite electrode.

36. The display device according to claim 24, wherein the hole-injecting layer comprises molybdenum oxide and aromatic amine.