Light emitting device and manufacturing method of the same

• US 20080252207A1
• Filed: 06/11/2008
• Published: 10/16/2008
• Est. Priority Date: 04/26/2002
• 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 8,044,580 B2
• Time in Patent Office: Days
• US Class Current: 313/504
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 50/818 Reflective anodes, e.g. ITO combined with thick metallic layers
• 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 50/844 Encapsulations
• CPC Class Codes: H10K 50/85 Arrangements for extracting light from the devices
• 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 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/124 Insulating layers formed between TFT elements and OLED elements
• CPC Class Codes: H10K 59/127 comprising two substrates, e.g. display comprising OLED array and TFT driving circuitry on different substrates
• CPC Class Codes: H10K 59/1315 comprising structures specially adapted for lowering the resistance
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]

Abstract

Not all of light generated in the light emitting layer comprising the organic material are taken out in the desirable direction. For example, light emitted in the lateral direction (the direction parallel to the substrate face) is not taken out and therefore is a loss. An object of the present invention is to provide a light emitting device structured so as to increase the amount of light which is taken out in a certain direction after emitted from a light emitting element, as well as a method of manufacturing this light emitting device.

In the present invention, an upper end portion of an insulating material 19 that covers an end portion of a first electrode 18 is formed to have a curved surface having a radius of curvature, a second electrode 23a is formed to have a slant face as going from its center portion toward its end portion along the curved surface. Light emitted from a light emitting layer comprising an organic material 20 that is formed on the second electrode 23a is reflected at the slant face of the second electrode 23a to increase the total amount of light taken out in the direction indicated by the arrow in FIG. 1A.

Claims

1-12. -12. (canceled)

13. A light emitting device comprising:

a transistor;

a first electrode connected to one of a source region of the thin film transistor and a drain region of the thin film transistor,

an insulating material covering an end portion of the first electrode,

a second electrode covering a side face of the insulating material and contacting with the first electrode,

a light emitting layer comprising an organic material on the second electrode and a portion of the insulating material,

a third electrode in contact with the light emitting layer comprising the organic material and a portion of the insulating material, and

an auxiliary electrode in contact with the third electrode and becoming the same electric potential as the third electrode,

wherein the auxiliary electrode comprises the same material as the second electrode.

14. A light emitting device according to claim 13, wherein the first electrode is the same in its electric potential as the second electrode, and is one of an anode and a cathode.

15. A light emitting device according to claim 13, wherein the second electrode is formed in a concave shape partially having a curved surface, and reflects a light emitted from the light emitting layer comprising the organic material.

16. A light emitting device according to claim 13, wherein the center portion of the second electrode contacts with the first electrode, and the insulating material exists between the end portion of the first electrode and an end portion of the second electrode.

17. A light emitting device according to claim 13, wherein the third electrode is a conductive film through which a light is transmitted.

18. A light emitting device according to claim 13, wherein the insulating material has in its upper end portion a curved surface possessing a radius of curvature, and the radius of curvature is 0.2 μ

m to 3 μ

m.

19. A light emitting device according to claim 13, wherein the insulating material has in its upper end portion a curved surface possessing a first radius of curvature and has in its lower end portion a curved surface possessing a second radius of curvature, and the first radius of curvature and the second radius of curvature are 0.2 μ

m to 3 μ

m.

20. A light emitting device according to claim 13, wherein the second electrode has a slant face, and its slant angle is 30°

to 70°

.

21. A light emitting device according to claim 13, wherein the light emitting layer comprising the organic material comprises one of a material emitting a red light, a material emitting a green light and a material emitting a blue light.

22. A light emitting device according to claim 13, wherein the light emitting layer comprising the organic material comprises a material emitting a white light, and is combined with a color filter.

23. A light emitting device according to claim 13, wherein the light emitting layer comprising the organic material is a material emitting a monochromatic light, and is combined with a color changing layer.

24. A light emitting device according to claim 13, wherein the light emitting device is one of selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation, a personal computer, a DVD player, an electronic game equipment and a portable information terminal.

25-60. -60. (canceled)

61. A method of manufacturing a light emitting device having the steps of comprising:

forming a thin film transistor;

forming an insulating material covering an end portion of a first electrode connected to one of a source region of the thin film transistor and a drain region of the thin film transistor,

forming a second electrode in contact with the first electrode and a side face of the insulating material, and an auxiliary electrode on and in contact with the insulating material,

forming a light emitting layer comprising an organic material to cover the second electrode and on a portion of the insulating material, and

forming a third electrode in contact with the light emitting layer comprising the organic material and a portion of the insulating material after forming the auxiliary electrode,

wherein the second electrode reflects a light emitted from the light emitting layer comprising the organic material, and

wherein the third electrode is a conductive film through which a light is transmitted.

62. A method of manufacturing a light emitting device according to claim 61, wherein the second electrode is an anode, and comprises a metal layer whose work function is larger than that of the third electrode.

63. A method of manufacturing a light emitting device according to claim 61, wherein the second electrode is a lamination of a first metal layer containing aluminum and a second metal layer containing one of titanium nitride and tungsten nitride.

64. A method of manufacturing a light emitting device according to claim 61, wherein the second electrode has a slant face directed toward a center portion of the second electrode, and its slant angle is 30°

to 70°

.

65. A method of manufacturing a light emitting device according to claim 61, wherein the insulating material covering an end portion of the first electrode has in its upper end portion a curved surface possessing a radius of curvature, and the radius of curvature is 0.2 μ

m to 3 μ

m.

66. A light emitting device comprising:

a transistor;

a first electrode connected to one of a source region of the thin film transistor and a drain region of the thin film transistor,

an insulating material covering an end portion of the first electrode,

a second electrode covering a side face of the insulating material and contacting with the first electrode,

a light emitting layer comprising an organic material on the second electrode and a portion of the insulating material,

a third electrode in contact with the light emitting layer comprising the organic material and a portion of the insulating material, and

an auxiliary electrode on the insulating material and in contact with the third electrode,

wherein the second electrode reflects a light emitted from the light emitting layer comprising the organic material, and

wherein the third electrode is a conductive film through which a light is transmitted.

67. A light emitting device according to claim 66, wherein the first electrode is the same in its electric potential as the second electrode, and is one of an anode and a cathode.

68. A light emitting device according to claim 66, wherein the second electrode is formed in a concave shape partially having a curved surface.

69. A light emitting device according to claim 66, wherein the center portion of the second electrode contacts with the first electrode, and the insulating material exists between the end portion of the first electrode and an end portion of the second electrode.

70. A light emitting device according to claim 66, wherein the insulating material has in its upper end portion a curved surface possessing a radius of curvature, and the radius of curvature is 0.2 μ

m to 3 μ

m.

71. A light emitting device according to claim 66, wherein the insulating material has in its upper end portion a curved surface possessing a first radius of curvature and has in its lower end portion a curved surface possessing a second radius of curvature, and the first radius of curvature and the second radius of curvature are 0.2 μ

m to 3 μ

m.

72. A light emitting device according to claim 66, wherein the second electrode has a slant face, and its slant angle is 30°

to 70°

.

73. A light emitting device according to claim 66, wherein the light emitting layer comprising the organic material comprises one of a material emitting a red light, a material emitting a green light and a material emitting a blue light.

74. A light emitting device according to claim 66, wherein the light emitting layer comprising the organic material comprises a material emitting a white light, and is combined with a color filter.

75. A light emitting device according to claim 66, wherein the light emitting layer comprising the organic material is a material emitting a monochromatic light, and is combined with a color changing layer.

76. A light emitting device according to claim 66, wherein the light emitting device is one of selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation, a personal computer, a DVD player, an electronic game equipment and a portable information terminal.

77. A light emitting device comprising:

a transistor;

an interlayer insulating film over the transistor;

a first electrode connected to one of a source region of the thin film transistor and a drain region of the thin film transistor,

an insulating material covering an end portion of the first electrode and over the interlayer insulating film,

a second electrode covering a side face of the insulating material and contacting with the first electrode,

a light emitting layer comprising an organic material on the second electrode and a portion of the insulating material,

a third electrode in contact with the light emitting layer comprising the organic material and a portion of the insulating material, and

an auxiliary electrode on the insulating material and in contact with the third electrode,

wherein the second electrode reflects a light emitted from the light emitting layer comprising the organic material, and

wherein the third electrode is a conductive film through which a light is transmitted.

78. A light emitting device according to claim 77, wherein the first electrode is the same in its electric potential as the second electrode, and is one of an anode and a cathode.

79. A light emitting device according to claim 77, wherein the second electrode is formed in a concave shape partially having a curved surface.

80. A light emitting device according to claim 77, wherein the center portion of the second electrode contacts with the first electrode, and the insulating material exists between the end portion of the first electrode and an end portion of the second electrode.

81. A light emitting device according to claim 77, wherein the insulating material has in its upper end portion a curved surface possessing a radius of curvature, and the radius of curvature is 0.2 μ

m to 3 μ

m.

82. A light emitting device according to claim 77, wherein the insulating material has in its upper end portion a curved surface possessing a first radius of curvature and has in its lower end portion a curved surface possessing a second radius of curvature, and the first radius of curvature and the second radius of curvature are 0.2 μ

m to 3 μ

m.

83. A light emitting device according to claim 77, wherein the second electrode has a slant face, and its slant angle is 30°

to 70°

.

84. A light emitting device according to claim 77, wherein the light emitting layer comprising the organic material comprises one of a material emitting a red light, a material emitting a green light and a material emitting a blue light.

85. A light emitting device according to claim 77, wherein the light emitting layer comprising the organic material comprises a material emitting a white light, and is combined with a color filter.

86. A light emitting device according to claim 77, wherein the light emitting layer comprising the organic material is a material emitting a monochromatic light, and is combined with a color changing layer.

87. A light emitting device according to claim 77, wherein the light emitting device is one of selected from the group consisting of a video camera, a digital camera, a goggle type display, a car navigation, a personal computer, a DVD player, an electronic game equipment and a portable information terminal.

88. A method of manufacturing a light emitting device comprising:

forming a thin film transistor;

forming an interlayer insulating film over the thin film transistor;

forming an insulating material over the interlayer insulating film, the insulating material covering an end portion of a first electrode connected to one of a source region of the thin film transistor and a drain region of the thin film transistor,

forming a second electrode in contact with the first electrode and a side face of the insulating material, and an auxiliary electrode on and in contact with the insulating material,

forming a light emitting layer comprising an organic material to cover the second electrode and on a portion of the insulating material, and

forming a third electrode in contact with the light emitting layer comprising the organic material and a portion of the insulating material after forming the auxiliary electrode,

wherein the second electrode reflects a light emitted from the light emitting layer comprising the organic material, and

wherein the third electrode is a conductive film through which a light is transmitted.

89. A method of manufacturing a light emitting device according to claim 88, wherein the second electrode is an anode, and comprises a metal layer whose work function is larger than that of the third electrode.

90. A method of manufacturing a light emitting device according to claim 88, wherein the second electrode is a lamination of a first metal layer containing aluminum and a second metal layer containing one of titanium nitride and tungsten nitride.

91. A method of manufacturing a light emitting device according to claim 88, wherein the second electrode has a slant face directed toward a center portion of the second electrode, and its slant angle is 30°

to 70°

.

92. A method of manufacturing a light emitting device according to claim 88, wherein the insulating material covering an end portion of the first electrode has in its upper end portion a curved surface possessing a radius of curvature, and the radius of curvature is 0.2 μ

m to 3 μ

m.