Stabilized electrodes in electroluminescent displays

• US 20030152803A1
• Filed: 12/19/2002
• Published: 08/14/2003
• Est. Priority Date: 12/20/2001
• Status: Active Grant

• Current Assignee: iFire IP Corporation
• Original Assignee: iFire Technology Inc.
• Inventors: Acchione, Joe
• Granted Patent: US 6,952,080 B2
• Time in Patent Office: Days
• US Class Current: 428/690
• CPC Class Codes: H05B 33/04 Sealing arrangements , e.g. against humidity
• CPC Class Codes: H05B 33/06 Electrode terminals
• CPC Class Codes: H05B 33/10 Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
• CPC Class Codes: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
• CPC Class Codes: H05B 33/26 characterised by the composition or arrangement of the conductive material used as an electrode
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

The invention relates to improving the stability of the lower electrodes in an electroluminescent display employing a thick film dielectric. The invention is an encapsulated electrode comprising an electrode of an electrically conductive metallic film. A layer of encapsulating material is provided on an upper and/or lower surface of the electrode layer. The encapsulating material reduces the risk of the electrode from becoming discontinuous and losing its electrical conductivity.

Claims

1. An encapsulated electrode comprising;

an electrode layer comprising an electrically conductive metallic film;

a layer of encapsulating material provided on an upper and/or lower surface of said electrode layer, said material reducing the risk of the electrode from becoming discontinuous and losing its electrical conductivity;

wherein said encapsulated electrode is present in a thick film dielectric electroluminescent display.

2. The encapsulated electrode of claim 1, wherein said encapsulating material does not decrease the fraction of the applied voltage across a phosphor film present in said thick film dielectric electroluminescent display.

3. The encapsulated electrode of claim 1, wherein said encapsulating material acts as a barrier to in-diffusion of species into said electrode from an adjacent substrate and/or thick film dielectric structure present in said thick film dielectric electroluminescent display.

4. The encapsulated electrode of claim 1, wherein said encapsulating material increases adhesion between the electrode and a substrate material that forms part of the thick film dielectric electroluminescent display.

5. The encapsulated electrode of claim 1, wherein said encapsulating material increases adhesion between the electrode and a thick dielectric layer present within the thick film dielectric electroluminescent display.

6. The encapsulated electrode of claim 1, wherein said electrically conductive metallic film has an surface oxide layer and said encapsulating material minimizes chemical reduction of said surface oxide layer.

7. The encapsulated electrode of claim 6, wherein said encapsulating material has a greater tendency to donate oxygen to a surface of said electrode than scavenge oxygen from said electrode.

8. The encapsulated electrode of claim 1, wherein said material is a dense crystalline material having a crystal structure that is not disrupted in the presence of a reducing agent selected from the group consisting of hydrogen sulfide, sulfur, sulfur vapour and sulfide bearing vapours.

9. The encapsulated electrode of claim 1, wherein said encapsulating material has a thickness of about 10 nm to about 500 nm.

10. The encapsulated electrode of claim 9, wherein said encapsulating material has a thickness of about 25 nm to about 450 nm.

11. The encapsulated electrode of claim 9, wherein said encapsulating material has a thickness of about 1 0 nm to about 60 nm.

12. The encapsulated electrode of claim 11, wherein said encapsulating material has a thickness of about 30 nm to about 60 nm.

13. The encapsulated electrode of claim 9, wherein said encapsulating material has a thickness of about 20 nm to about 500 nm.

14. The encapsulated electrode of claim 13, wherein said encapsulating material has a thickness of about 100 nm to about 450 nm.

15. The encapsulated electrode of claim 1, wherein said encapsulating material is an oxide.

16. The encapsulated electrode of claim 15, wherein said oxide is indium tin oxide.

17. The encapsulated electrode of claim 1, wherein said encapsulating material is a compound having a high dielectric constant.

18. The encapsulated electrode of claim 17, wherein said compound is barium titanate.

19. The encapsulated electrode of claim 9, wherein said encapsulating material is provided on a lower surface of said electrode layer and has a thickness of about 10 nm to about 60 nm.

20. The encapsulated electrode of claim 9, wherein said encapsulating material is provided on an upper surface of said electrode layer and has a thickness of about 20 nm to about 500 nm.

21. The encapsulated electrode of claim 19, wherein said electrode has a thickness of about 100 nm to about 1000 nm.

22. The encapsulated electrode of claim 21, wherein said electrode has a thickness of about 150 nm to about 250 nm.

23. The encapsulated electrode of claim 21, wherein said electrode is a metallic gold film.

24. The encapsulated electrode of claim 9, wherein said encapsulating material is provided on both said upper and lower surfaces of said electrode layer and said encapsulating material comprises indium tin oxide.

25. The encapsulated electrode of claim 9, wherein said encapsulating material is provided on both said upper and lower surfaces of said electrode layer and said encapsulating material comprises barium titanate.

26. The encapsulated electrode of claim 9, wherein said encapsulating material provided on said upper surface of said electrode layer is indium tin oxide and said encapsulating material provided on said lower surface of said electrode is barium titanate.

27. The encapsulated electrode of claim 9, wherein said encapsulating material provided on said upper surface of said electrode is barium titanate and said encapsulating material provided on said lower surface of said electrode is indium tin oxide.

28. The encapsulated electrode of claim 26, wherein said encapsulating material on said upper surface of said electrode has a thickness of about 20 nm to about 500 nm.

29. The encapsulated electrode of claim 26, wherein said encapsulating material on said lower surface of said electrode has a thickness of about 10 nm to about 60 nm.

30. A thick film dielectric electroluminescent display having an encapsulated lower electrode that comprises;

an electrode layer comprising an electrically conductive metallic film; and

an encapsulating material provided on an upper and/or lower surface of said electrode, said encapsulating material minimizing the electrode from becoming discontinuous and losing its electrical conductivity.

31. The thick film dielectric electroluminescent display of claim 30, further comprising;

a rigid heat resistant substrate;

said electrode layer placed directly adjacent said substrate, said electrode layer comprising an electrically conductive metallic film;

a thick film dielectric layer adjacent said layer of encapsulating material provided on an upper surface of said electrode layer;

a phosphor film deposited on said thick film dielectric layer; and

an upper electrode layer comprising an optically transparent electrically conductive film provided above said phosphor film.

32. The display of claim 31, wherein said layer of encapsulating material comprises an oxide.

33. The display of claim 31, wherein said layer of encapsulating material comprises a compound with a high dielectric constant.

34. The display of claim 32, wherein said oxide is indium tin oxide.

35. The display of claim 33, wherein said compound is barium titanate.

36. The display of claim 34, wherein said indium tin oxide or barium titanate is provided as a layer with a thickness of about 10 nm to 500 nm.

37. The display of claim 36, wherein said thickness is about 10 nm to about 450 nm.

38. The display of claim 36, wherein said indium tin oxide is provided on an upper surface of said electrode layer and has a thickness of about 100 nm to about 450 nm.

39. The display of claim 36, wherein said barium titanate is provided on a lower surface of said electrode layer and has a thickness of about 30 nm to about 60 nm.

40. The display of claim 36, further comprising a sealing layer over the entire display to protect from moisture and/or atmospheric contaminants.

41. A method for stabilizing an electrode within a thick film dielectric electroluminescent display, said method comprising;

providing a layer of encapsulating material on an upper and/or lower surface of said electrode, said encapsulating material reducing the risk of the electrode from becoming discontinuous and losing its electrical conductivity.

42. The method of claim 41, wherein said encapsulating material does not decrease the fraction of the applied voltage across a phosphor film present in a thick film dielectric electroluminescent display.

43. The method of claim 41, wherein said encapsulating material acts as a barrier to in-diffusion of species into said electrode from adjacent substrate and/or thick film dielectric structures present in a thick film dielectric electroluminescent display.

44. The method of claim 41, wherein said electrically conductive metallic film has a surface oxide layer and said encapsulating material minimizes chemical reduction of said surface oxide layer.

45. The method of claim 44, wherein said encapsulating material has a greater tendency to donate oxygen to a surface of said electrode than scavenge oxygen from said electrode.

46. The method of claim 41, wherein said material is a dense crystalline material having a crystal structure that is not disrupted in the presence of a reducing agent selected from the group consisting of hydrogen sulfide, sulfur, sulfur vapour and sulfide bearing vapours.

47. The method of claim 41, wherein said encapsulating material is an oxide.

48. The method of claim 47, wherein said oxide is indium tin oxide.

49. The method of claim 41, wherein said encapsulating material is a compound having a high dielectric constant.

50. The method of claim 49, wherein said compound is barium titanate.

51. The method of claim 48, wherein said encapsulating material has a thickness of about 10 nm to about 500 nm.

52. The method of claim 51, wherein said encapsulating material has a thickness of about 25 nm to about 450 nm.

53. The method of claim 51, wherein said encapsulating material is provided on a lower surface of said electrode layer and has a thickness of about 10 nm to about 60 nm.

54. The method of claim 53, wherein said encapsulating material has a thickness of about 30 nm to about 60 nm.

55. The method of claim 51, wherein said encapsulating material is provided on an upper surface of said electrode layer and has a thickness of about 20 nm to about 500 nm.

56. The method of claim 55, wherein said encapsulating material has a thickness of about 100 nm to about 450 nm.

57. The method of claim 51, wherein said electrode has a thickness of about 100 nm to about 1000 nm.

58. The method of claim 57, wherein said electrode has a thickness of about 150 nm to about 250 nm.

59. The method of claim 57, wherein said electrode is a metallic gold film.

60. The method of claim 51, wherein said encapsulating material is provided on both said upper and lower surfaces of said electrode and said encapsulating material comprises indium tin oxide.

61. The method of claim 51, wherein said encapsulating material is provided on both said upper and lower surfaces of said electrode and said encapsulating material comprises barium titanate.

62. The method of claim 51, wherein said encapsulating material provided on said upper surface of said electrode is indium tin oxide and said encapsulating material provided on said lower surface of said electrode is barium titanate.

63. The method of claim 51, wherein said encapsulating material provided on said upper surface of said electrode is barium titanate and said encapsulating material provided on said lower surface of said electrode is indium tin oxide.

64. The method of claim 51, wherein said encapsulating material is provided by sputtering.

65. The method of claim 51, wherein said encapsulating material increases adhesion between the electrode and a substrate material that forms part of the thick film dielectric electroluminescent display.

66. The method of claim 51, wherein said encapsulating material increases adhesion between the electrode and a thick dielectric layer present within the thick film dielectric electroluminescent display.

67. A stabilized electrode comprising;

an electrically conductive gold film layer having an upper surface and a lower surface, said gold film having a thickness of about 100 nm to about 1000 nm;

a layer of indium tin oxide provided on the upper surface of said gold film layer having a thickness of about 20 nm to about 500 nm; and

a layer of indium tin oxide provided on the lower surface of said gold layer having a thickness of about 10 nm to about 60 nm;

wherein said stabilized electrode is present within a thick film dielectric electroluminescent display.

68. A stabilized electrode comprising;

an electrically conductive gold film layer having an upper surface and a lower surface, said gold film layer having a thickness of about 100 nm to about 100 nm;

a layer of barium titanate having a thickness of about 20 nm to about 500 nm provided on the upper surface of said gold layer; and

a layer of barium titanate having a thickness of about 10 nm to about 60 nm provided on the lower surface of said gold layer;

wherein said stabilized electrode is present within a thick film dielectric electroluminescent display.