Light emitting device and method of manufacturing the same

• US 20030197466A1
• Filed: 04/21/2003
• Published: 10/23/2003
• Est. Priority Date: 04/23/2002
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kuwabara, Hideaki, Seo, Satoshi, Yamazaki, Shunpei
• Granted Patent: US 7,579,771 B2
• Time in Patent Office: Days
• US Class Current: 313/504
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 50/813 characterised by their shape
• CPC Class Codes: H10K 50/818 Reflective anodes, e.g. ITO combined with thick metallic layers
• CPC Class Codes: H10K 50/82 Cathodes
• CPC Class Codes: H10K 50/824 combined with auxiliary electrodes
• CPC Class Codes: H10K 50/828 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 50/84 Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 50/841 Self-supporting sealing arrangements
• CPC Class Codes: H10K 50/844 Encapsulations
• CPC Class Codes: H10K 50/856 comprising reflective means
• CPC Class Codes: H10K 59/122 Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 59/30 Devices specially adapted for multicolour light emission
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]
• CPC Class Codes: H10K 59/80515 characterised by their shape
• CPC Class Codes: H10K 59/80518 Reflective anodes, e.g. ITO combined with thick metallic layers
• CPC Class Codes: H10K 59/80522 combined with auxiliary electrodes
• CPC Class Codes: H10K 59/80524 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 59/871 Self-supporting sealing arrangements
• CPC Class Codes: H10K 59/873 Encapsulations
• CPC Class Codes: H10K 59/878 : comprising reflective means

Abstract

All lights generated in an organic compound layer are not taken out towards a TFT from a cathode as a transparent electrode. For instance, the light is emitted in a lateral direction (direction parallel to the substrate surface) but the light emitted in the lateral direction is not taken out resultantly, which leads to a loss. Therefore, a light emitting device structured so as to increase the amount of light taken out in a certain direction is provided as well as a method of manufacturing this light emitting device. As a result of etching treatment, an upper edge portion of an insulator (19) is curved to have a radius of curvature, a slope is formed along the curved face while partially exposing layers (18c and 18d) of a first electrode, and a layer (18b) of the first electrode is exposed in a region that serves as a light emitting region. Light emitted from an organic compound layer (20) is reflected by the slope of the first electrode (layers 18c and 18d) to increase the total amount of light taken out in the direction indicated by the arrow in FIG. 1A.

Claims

1. A light emitting device comprising:

a first electrode connected to a thin film transistor over a substrate having an insulating surface;

an insulator covering an edge portion of the first electrode;

a layer comprising an organic compound formed over the first electrode; and

a second electrode over the layer,

wherein the first electrode is sloped from its edge portion toward its center to have a slope and that the slope reflects light emitted from the organic compound-containing layer.

4. A light emitting device according to claim 1, wherein the second electrode is a transmissive conductive film.

7. A light emitting device according to claim 1, wherein the first electrode has a concave shape and is formed in a self-aligning manner using the insulator as a mask.

10. A light emitting device according to claim 1, wherein the first electrode is an anode and the second electrode is a cathode.

13. A light emitting device according to claim 1, wherein the first electrode is a cathode and the second electrode is an anode.

16. A light emitting device according to claim 1, wherein the first electrode is sloped toward its center and the angle of inclination of the slope is more than 30°

and less than 70°

.

19. A light emitting device according to claim 1, wherein an upper edge portion of the insulator for covering the edge portion of the first electrode is curved to have a radius of curvature and the radius of curvature is set to 0.2 to 3 μ

m.

22. A light emitting device according to claim 1, wherein the layer containing the organic compound is made of a material emitting red light, green light, or blue light.

25. A light emitting device according to claim 1, wherein the layer containing the organic compound is made of a material emitting white light, and is combined with a color filter provided in a sealing member.

28. A light emitting device according to claim 1, wherein the layer containing the organic compound is made of a material emitting monochromatic light, and is combined with one of a color conversion layer and a colored layer provided in a sealing member.

31. A light emitting element according to claim 1, wherein the light emitting device is any one of a video camera, a digital camera, a goggle-type display, a car navigation system, a personal computer, a DVD player, a electronic game machine, and a portable information terminal.

2. A light emitting device comprising:

a first electrode connected to a thin film transistor over a substrate having an insulating surface;

an insulator covering an edge portion of the first electrode;

a layer comprising an organic compound formed over the first electrode; and

a second electrode over the layer,

wherein the first electrode is thinner in the center than in the edge portion to form a depressive shape.

5. A light emitting device according to claim 2, wherein the second electrode is a transmissive conductive film.

8. A light emitting device according to claim 2, wherein the first electrode has a concave shape and is formed in a self-aligning manner using the insulator as a mask.

11. A light emitting device according to claim 2, wherein the first electrode is an anode and the second electrode is a cathode.

14. A light emitting device according to claim 2, wherein the first electrode is a cathode and the second electrode is an anode.

17. A light emitting device according to claim 2, wherein the first electrode is sloped toward its center and the angle of inclination of the slope is more than 30°

and less than 70°

.

20. A light emitting device according to claim 2, wherein an upper edge portion of the insulator for covering the edge portion of the first electrode is curved to have a radius of curvature and the radius of curvature is set to 0.2 to 3 μ

m.

23. A light emitting device according to claim 2, wherein the layer containing the organic compound is made of a material emitting red light, green light, or blue light.

26. A light emitting device according to claim 2, wherein the layer containing the organic compound is made of a material emitting white light, and is combined with a color filter provided in a sealing member.

29. A light emitting device according to claim 2, wherein the layer containing the organic compound is made of a material emitting monochromatic light, and is combined with one of a color conversion layer and a colored layer provided in a sealing member.

32. A light emitting element according to claim 2, wherein the light emitting device is any one of a video camera, a digital camera, a goggle-type display, a car navigation system, a personal computer, a DVD player, a electronic game machine, and a portable information terminal.

3. A light emitting device comprising:

a first electrode connected to a thin film transistor on a substrate having an insulating surface;

an insulator covering an edge portion of the first electrode;

a layer comprising an organic compound formed over the first electrode; and

a second electrode over the layer,

wherein the first electrode has a multi-layer structure and that the number of layers is larger in the edge portion than in the center.

6. A light emitting device according to claim 3, wherein the second electrode is a transmissive conductive film.

9. A light emitting device according to claim 3, wherein the first electrode has a concave shape and is formed in a self-aligning manner using the insulator as a mask.

12. A light emitting device according to claim 3, wherein the first electrode is an anode and the second electrode is a cathode.

15. A light emitting device according to claim 3, wherein the first electrode is a cathode and the second electrode is an anode.

18. A light emitting device according to claim 3, wherein the first electrode is sloped toward its center and the angle of inclination of the slope is more than 30°

and less than 70°

.

21. A light emitting device according to claim 3, wherein an upper edge portion of the insulator for covering the edge portion of the first electrode is curved to have a radius of curvature and the radius of curvature is set to 0.2 to 3 μ

m.

24. A light emitting device according to claim 3, wherein the layer containing the organic compound is made of a material emitting red light, green light, or blue light.

27. A light emitting device according to claim 3, wherein the layer containing the organic compound is made of a material emitting white light, and is combined with a color filter provided in a sealing member.

30. A light emitting device according to claim 3, wherein the layer containing the organic compound is made of a material emitting monochromatic light, and is combined with one of a color conversion layer and a colored layer provided in a sealing member.

33. A light emitting element according to claim 3, wherein the light emitting device is any one of a video camera, a digital camera, a goggle-type display, a car navigation system, a personal computer, a DVD player, a electronic game machine, and a portable information terminal.

34. A method of manufacturing a light emitting device including a light emitting element having:

an anode;

a layer containing an organic compound in contact with the anode; and

a cathode in contact with the layer containing the organic compound, comprising;

a step of forming an insulator to cover the edge of a first electrode that is a laminate of metal layers;

a step of thinning the center of the first electrode so as to expose a slope along the edge of the first electrode by etching using the insulator as a mask;

a step of forming the organic compound-containing film; and

a step of forming a second electrode on the organic compound-containing film from a thin metal film that transmits light.

35. A method of manufacturing a light emitting device according to claims 34, wherein the first electrode is a laminate of a metal layer reflecting light and a metal layer serving as an etching stopper and that the metal layer reflecting light is etched to expose a metal material that reflects light in the slope.

36. A method of manufacturing a light emitting device according to claim 34, wherein the first electrode is an anode and is formed from a metal layer that is larger in work function than the second electrode.

37. A method of manufacturing a light emitting device according to claim 34, wherein the first electrode is a laminate of a first metal layer containing titanium, a second metal layer containing titanium nitride or tungsten nitride, a third metal layer containing aluminum, and a fourth metal layer containing titanium nitride.

38. A method of manufacturing a light emitting device according to claim 34, wherein the first electrode is sloped toward its center and the angle of inclination of the slope is more than 30°

and less than 70°

.

39. A method of manufacturing a light emitting device according to claim 34, wherein an upper edge of the insulator for covering the edge portion of the first electrode is curved to have a radius of curvature and the radius of curvature is set to 0.2 to 3 μ

m.

40. A light emitting device comprising:

a first electrode having a depression connected to a thin film transistor over a substrate having an insulating surface;

an insulator covering an edge portion of the first electrode;

a layer comprising an organic compound covering at least the depression of the first electrode;

a second electrode over the layer;

wherein a width of bottom of the depression is smaller than a width of upper surface of the depression.