Light-emitting element including electrode of three layers

• US 9,564,609 B2
• Filed: 02/09/2012
• Issued: 02/07/2017
• Est. Priority Date: 02/11/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Sasaki, Toshiki, Sugisawa, Nozomu, Ikeda, Hisao, Seo, Satoshi, Ohsawa, Nobuharu, Yamazaki, Shunpei
• Primary Examiner(s): Ahmadi, Mohsen
• Assistant Examiner(s): MUSE, ISMAIL A
• Application Number:
  US13/369,797
• Publication Number:
  US 20120205701A1
• Time in Patent Office: 1,825 Days
• Field of Search: 257/40, 257/94, 313/504, 313/506, 313/512, 438/597
• US Class Current: 1/1
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/818 Reflective anodes, e.g. ITO combined with thick metallic layers
• CPC Class Codes: H10K 50/852 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: Y02E 10/549 Organic PV cells

Abstract

A light-emitting element disclosed includes a first electrode layer; a second electrode layer which transmits light; and a light-emitting layer interposed between the first electrode layer and the second electrode layer. The first electrode layer includes a first conductive layer which is able to reflect light, a second conductive layer provided over the first conductive layer and including titanium, and a third conductive layer which transmits light and contains a metal oxide having work function higher than that of a material of the first conductive layer.

Claims

1. A light-emitting element comprising:

a first electrode on a first insulating layer, the first electrode comprising a first conductive layer, a second conductive layer over and directly in contact with the first conductive layer, and a third conductive layer over and directly in contact with the second conductive layer;

a second insulating layer over and in contact with the third conductive layer, the second insulating layer comprising an opening portion which overlaps with the third conductive layer;

a hole-injection layer over and in contact with the third conductive layer and the second insulating layer, the hole-injection layer comprising an organic compound having a hole-transporting property and a metal oxide selected from vanadium oxide and molybdenum oxide;

a hole-transport layer over and in contact with the hole-injection layer;

an electroluminescent layer over and in contact with the hole-transport layer; and

a second electrode over the electroluminescent layer

wherein the electroluminescent layer overlaps with the first electrode;

wherein the first conductive layer is a metal alloy layer consisting essentially of aluminum and titanium,

wherein the second conductive layer is a metal layer consisting essentially of titanium,

wherein the third conductive layer comprises a metal oxide selected from indium oxide, tin oxide, zinc oxide, and indium oxide-tin oxide,

wherein the first conductive layer is in direct contact with the first insulating layer,

and wherein the second electrode is capable of transmitting light.

2. The light-emitting element according to claim 1, wherein the electroluminescent layer emits white light.

3. The light-emitting element according to claim 1, further comprising a colored layer over the second electrode.

4. An electronic device comprising the light-emitting element according to claim 1.

5. A lighting device comprising the light-emitting element according to claim 1.

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

wherein part of the second conductive layer is oxidized.

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

wherein the third conductive layer further comprises silicon.

8. The light-emitting element according to claim 1, wherein the first electrode is electrically connected to a source or a drain electrode of a transistor.

9. The light-emitting element according to claim 8, wherein the first insulating layer is over the source or the drain electrode.

10. A light-emitting element comprising:

a first electrode on a first insulating layer, the first electrode comprising a first conductive layer, a second conductive layer over and directly in contact with the first conductive layer, and a third conductive layer over and directly in contact with the second conductive layer;

a second insulating layer over and in contact with the third conductive layer, the second insulating layer comprising an opening portion which overlaps with the third conductive layer;

a hole-injection layer over and in contact with the third conductive layer and the second insulating layer, the hole-injection layer comprising an organic compound having a hole-transporting property and a metal oxide selected from vanadium oxide and molybdenum oxide;

a hole-transport layer over and in contact with the hole-injection layer;

an electroluminescent layer over and in contact with the hole-transport layer, the electroluminescent layer comprising a first light-emitting unit over the first electrode, a charge generation layer over the first light-emitting unit, and a second light-emitting unit over the charge generation layer; and

a second electrode over the electroluminescent layer,

wherein the electroluminescent layer overlaps with the first electrode;

wherein the first conductive layer is a metal alloy layer consisting essentially of aluminum and titanium,

wherein the second conductive layer is a metal layer consisting essentially of titanium,

wherein the third conductive layer comprises a metal oxide selected from indium oxide, tin oxide, zinc oxide, and indium oxide-tin oxide,

wherein the first conductive layer is in direct contact with the first insulating layer,

and wherein the second electrode is capable of transmitting light.

11. The light-emitting element according to claim 10, wherein the electroluminescent layer emits white light.

12. The light-emitting element according to claim 10, further comprising a colored layer over the second electrode.

13. The light-emitting element according to claim 10, wherein the charge generation layer comprises:

an electron-injection buffer layer comprising a material having an electron-transporting property higher than a hole-transporting property and an electron-donating property selected from an alkali metal, an alkaline earth metal, a compound of the alkali metal, and a compound of the alkaline earth metal; and

a composite material layer comprising a substance having a hole-transporting property and an acceptor substance.

14. An electronic device comprising the light-emitting element according to claim 10.

15. A lighting device comprising the light-emitting element according to claim 10.

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

wherein part of the second conductive layer is oxidized.

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

wherein the third conductive layer further comprises silicon.

18. The light-emitting element according to claim 10, wherein the first electrode is electrically connected to a source or a drain electrode of a transistor.

19. The light-emitting element according to claim 18, wherein the first insulating layer is over the source or the drain electrode.

20. A light-emitting element comprising:

a first electrode on a first insulating layer, the first electrode comprising a first conductive layer, a second conductive layer over and directly in contact with the first conductive layer, and a third conductive layer over and directly in contact with the second conductive layer;

a second insulating layer over and in contact with the third conductive layer, the second insulating layer comprising an opening portion which overlaps with the third conductive layer;

a hole-injection layer over and in contact with the third conductive layer and the second insulating layer, the hole-injection layer comprising an organic compound having a hole-transporting property and a metal oxide selected from vanadium oxide and molybdenum oxide;

a hole-transport layer over and in contact with the hole-injection layer;

an electroluminescent layer over and in contact with the hole-transport layer, the electroluminescent layer comprising a first light-emitting unit, a first charge generation layer over the first light-emitting unit, a second light-emitting unit over the first charge generation layer, a second charge generation layer over the second light-emitting unit, and a third light-emitting unit over the second charge generation layer; and

a second electrode over the electroluminescent layer,

wherein the electroluminescent layer overlaps with the first electrode;

wherein the first conductive layer is a metal alloy layer consisting essentially of aluminum and titanium,

wherein the second conductive layer is a metal layer consisting essentially of titanium,

wherein the third conductive layer comprises a metal oxide selected from indium oxide, tin oxide, zinc oxide, and indium oxide-tin oxide,

wherein the first conductive layer is in direct contact with the first insulating layer,

and wherein the second electrode is capable of transmitting light.

21. The light-emitting element according to claim 20, wherein the electroluminescent layer emits white light.

22. The light-emitting element according to claim 20, further comprising a colored layer over the second electrode.

23. The light-emitting element according to claim 20, wherein the first charge generation layer and the second charge generation layer comprise:

an electron-injection buffer layer comprising a material having an electron-transporting property higher than a hole-transporting property and an electron-donating property selected from an alkali metal, an alkaline earth metal, a compound of the alkali metal, and a compound of the alkaline earth metal; and

a composite material layer comprising a substance having a hole-transporting property and an acceptor substance.

24. An electronic device comprising the light-emitting element according to claim 20.

25. A lighting device comprising the light-emitting element according to claim 20.

26. The light-emitting element according to claim 20,

wherein part of the second conductive layer is oxidized.

27. The light-emitting element according to claim 20,

wherein the third conductive layer further comprises silicon.

28. The light-emitting element according to claim 20, wherein the first electrode is electrically connected to a source or a drain electrode of a transistor.

29. The light-emitting element according to claim 28, wherein the first insulating layer is over the source or the drain electrode.