Light emitting device and method of manufacturing the same

• US 20030062826A1
• Filed: 09/26/2002
• Published: 04/03/2003
• Est. Priority Date: 09/28/2001
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Seo, Satoshi, Nakamura, Yasuo
• Granted Patent: US 7,193,359 B2
• Time in Patent Office: Days
• US Class Current: 313/504
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 50/18 Carrier blocking layers
• CPC Class Codes: H10K 50/81 Anodes
• CPC Class Codes: H10K 50/828 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 50/865 comprising light absorbing layers, e.g. light-blocking layers
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 59/8051 Anodes
• CPC Class Codes: H10K 59/80524 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 59/8792 comprising light absorbing layers, e.g. black layers

Abstract

A measure for improving the light emission efficiency of a light emitting element without degrading characteristics of anode materials used in prior art is provided in manufacture of an upward emission type light emitting element. The present invention is characterized in that nitride or carbide of a metal element belonging to one of Group 4, 5, and 6 in the periodic table (hereinafter referred to as metal compound) is used as the material for forming an anode of a light emitting element. The metal compound has a work function equal to or larger than the work function of conventional anode materials. Therefore, injection of holes from the anode can be improved ever more. Also, with regard to conductivity, the metal compound is smaller in resistivity than ITO. It therefore can fulfil the function as a wire and can lower the drive voltage in the light emitting element compared to prior art.

Claims

1. A light emitting device having an anode, a cathode, and a layer comprising at least one organic compound,

wherein the layer comprising at least one organic compound is interposed between the anode and the cathode,

wherein the anode has a light-shielding ability and contains an element that belongs to one of Group 4, 5, and 6 in the periodic table, and

wherein the cathode comprises a light-transmissive conductive film.

2. A device according to claim 1, wherein the anode comprises a material having a resistivity of 1×

10<sup>−

2</sup> Ω

cm or less.

3. A device according to claim 1, wherein the anode comprises a material having a work function of 4.7 eV or more.

4. A device according to claim 1, wherein the anode comprises one selected from the group consisting of titanium nitride, zirconium nitride, titanium carbide, zirconium carbide, tantalum nitride, tantalum carbide, molybdenum nitride, and molybdenum carbide.

5. A device according to claim 1, wherein the light emitting device is one selected from the group consisting of a display device, a digital still camera, a notebook personal computer, a mobile computer, a portable image reproducing device with a recording medium, a goggle-type display, a video camera, and a cellular phone.

6. A light emitting device having an anode, a cathode, and a layer comprising at least one organic compound,

wherein the layer comprising at least one organic compound is interposed between the anode and the cathode,

wherein the anode has a light-shielding ability and comprises one of nitride and carbide of an element that belongs to one of Group 4, 5, and 6 in the periodic table, and

wherein the cathode comprises a light-transmissive conductive film.

7. A device according to claim 6, wherein the anode comprises a material having a resistivity of 1×

10<sup>−

2</sup> Ω

cm or less.

8. A device according to claim 6, wherein the anode comprises a material having a work function of 4.7 eV or more.

9. A device according to claim 6, wherein the anode comprises one selected from the group consisting of titanium nitride, zirconium nitride, titanium carbide, zirconium carbide, tantalum nitride, tantalum carbide, molybdenum nitride, and molybdenum carbide.

10. A device according to claim 6, wherein the light emitting device is one selected from the group consisting of a display device, a digital still camera, a notebook personal computer, a mobile computer, a portable image reproducing device with a recording medium, a goggle-type display, a video camera, and a cellular phone.

11. A light emitting device having a TFT provided on an insulating surface and a light emitting element,

wherein the light emitting element has an anode, a cathode, and a layer comprising at least one organic compound,

wherein the TFT is electrically connected to the anode, and

wherein the anode contains an element that belongs to one of Group 4, 5, and 6 in the periodic table.

12. A device according to claim 11, wherein the cathode comprises a light-transmissive conductive film.

13. A device according to claim 11, wherein the anode comprises a material having a resistivity of 1×

10<sup>−

2</sup> Ω

cm or less.

14. A device according to claim 11, wherein the anode comprises a material having a work function of 4.7 eV or more.

15. A device according to claim 11, wherein the anode comprises one selected from the group consisting of titanium nitride, zirconium nitride, titanium carbide, zirconium carbide, tantalum nitride, tantalum carbide, molybdenum nitride, and molybdenum carbide.

16. A device according to claim 11, wherein the light emitting device is one selected from the group consisting of a display device, a digital still camera, a notebook personal computer, a mobile computer, a portable image reproducing device with a recording medium, a goggle-type display, a video camera, and a cellular phone.

17. A light emitting device having a TFT provided on an insulating surface and a light emitting element,

wherein the light emitting element has an anode, a cathode, and a layer comprising at least one organic compound,

wherein the TFT is electrically connected to the anode, and

wherein the anode comprises one of nitride and carbide of an element that belongs to one of Group 4, 5, and 6 in the periodic table.

18. A device according to claim 17, wherein the cathode comprises a light-transmissive conductive film.

19. A device according to claim 17, wherein the anode comprises a material having a resistivity of 1×

10<sup>−

2</sup> Ω

cm or less.

20. A device according to claim 17, wherein the anode comprises a material having a work function of 4.7 eV or more.

21. A device according to claim 17, wherein the anode comprises one selected from the group consisting of titanium nitride, zirconium nitride, titanium carbide, zirconium carbide, tantalum nitride, tantalum carbide, molybdenum nitride, and molybdenum carbide.

22. A device according to claim 17, wherein the light emitting device is one selected from the group consisting of a display device, a digital still camera, a notebook personal computer, a mobile computer, a portable image reproducing device with a recording medium, a goggle-type display, a video camera, and a cellular phone.

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

forming an anode on an insulating surface;

subjecting a surface of the anode to UV ozone treatment;

forming a layer comprising at least one organic compound on the anode; and

forming a cathode on the layer comprising at least one organic compound,

wherein the anode contains an element that belongs to one of Group 4, 5, and 6 in the periodic table.

24. A method according to claim 23, wherein said anode is electrically connected to a TFT that is formed over a substrate.

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

forming an anode on an insulating surface;

subjecting a surface of the anode to UV ozone treatment;

forming a layer comprising at least one organic compound on the anode; and

forming a cathode on the layer comprising at least one organic compound,

wherein the anode is formed of one of nitride and carbide of an element that belongs to one of Group 4, 5, and 6 in the periodic table.

26. A method according to claim 25, wherein said anode is electrically connected to a TFT that is formed over a substrate.

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

forming an anode on an insulating surface;

subjecting a surface of the anode to UV ozone treatment;

forming a layer comprising at least one organic compound on the anode; and

forming a cathode on the layer comprising at least one organic compound,

wherein the anode has a light-shielding ability and contains an element that belongs to one of Group 4, 5, and 6 in the periodic table, and

wherein the cathode is formed from a light-transmissive conductive film.

28. A method according to claim 27, wherein said anode is electrically connected to a TFT that is formed over a substrate.

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

forming an anode on an insulating surface;

subjecting a surface of the anode to UV ozone treatment;

forming a layer comprising at least one organic compound on the anode; and

forming a cathode on the layer comprising at least one organic compound,

wherein the anode has a light-shielding ability and comprising one of nitride and carbide of an element that belongs to one of Group 4, 5, and 6 in the periodic table, and

wherein the cathode is formed from a light-transmissive conductive film.

30. A method according to claim 29, wherein said anode is electrically connected to a TFT that is formed over a substrate.

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

forming an anode on an insulating surface;

subjecting a surface of the anode to plasma treatment;

forming a layer comprising at least one organic compound on the anode; and

forming a cathode on the layer comprising at least one organic compound,

wherein the anode contains an element that belongs to one of Group 4, 5, and 6 in the periodic table.

32. A method according to claim 31, wherein said anode is electrically connected to a TFT that is formed over a substrate.

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

forming an anode on an insulating surface;

subjecting a surface of the anode to plasma treatment;

forming a layer comprising at least one organic compound on the anode; and

forming a cathode on the layer comprising at least one organic compound,

wherein the anode comprises one of nitride and carbide of an element that belongs to one of Group 4, 5, and 6 in the periodic table.

34. A method according to claim 33, wherein said anode is electrically connected to a TFT that is formed over a substrate.

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

forming an anode on an insulating surface;

subjecting a surface of the anode to plasma treatment;

forming an organic compound layer on the anode; and

forming a cathode on the organic compound layer,

wherein the anode has a light-shielding ability and contains an element that belongs to one of Group 4, 5, and 6 in the periodic table, and

wherein the cathode comprises a light-transmissive conductive film.

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

forming an anode on an insulating surface;

subjecting a surface of the anode to plasma treatment;

forming a layer comprising at least one organic compound on the anode; and

forming a cathode on the layer comprising at least one organic compound,

wherein the anode has a light-shielding ability and comprises one of nitride and carbide of an element that belongs to one of Group 4, 5, and 6 in the periodic table, and

wherein the cathode comprises a light-transmissive conductive film.

36. A method according to claim 37, wherein said anode is electrically connected to a TFT that is formed over a substrate.

38. A method according to claim 38, wherein said anode is electrically connected to a TFT that is formed over a substrate.