Bipolar electroluminescent device

• US 5,663,573 A
• Filed: 03/17/1995
• Issued: 09/02/1997
• Est. Priority Date: 03/17/1995
• Status: Expired due to Term

• Current Assignee: Ohio State Innovation Foundation (Ohio State University)
• Original Assignee: Ohio State University
• Inventors: Wang, Yunzhang, Epstein, Arthur J., Gebler, Darren Douglas
• Primary Examiner(s): MINTEL, WILLIAM A
• Application Number:
  US08/406,512
• Time in Patent Office: 900 Days
• Field of Search: 257/103, 257/40, 257/99, 313/504, 313/503, 313/501, 313/506
• US Class Current: 257/40
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: H05B 33/20 characterised by the chemical or physical composition or the arrangement of the material in which the electroluminescent material is embedded
• 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: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 71/841 Applying alternating current [AC] during manufacturing or treatment

Abstract

Light-emitting bipolar devices consist of a light-emitter formed from an electroluminescent organic light-emitting material in contact with an insulating material. The light emitter is in contact with two electrodes that are maintained in spaced apart relation with each other. The light emitter can be formed as an integral mixture of light emitting materials and insulating materials or as separate layers of light-emitting and insulating materials. The devices operate with AC voltage of less than twenty-four volts and in some instances at less than five volts. Under AC driving, the devices produce modulated light output that can be frequency or amplitude modulated. Under DC driving, the devices operate in both forward and reverse bias.

Claims

1. A bipolar electroluminescent device comprising:

a. a light emitter operating in both a forward and a reverse current direction and comprising an electroluminescent organic light emitting means in contact with an insulating means;

b. a first electrode means in contact with said light emitter and for electrically connecting said first electrode to a potential difference; and

c. a second electrode means in contact with said light emitter and in spaced relation with said first electrode and for electrically connecting said second electrode to said potential difference.

2. The bipolar electroluminescent device according to claim 1 wherein said potential difference is an alternating potential difference.

3. The bipolar electroluminescent device according to claim 1 wherein said insulating means is selected from the group of insulating means consisting of ceramic insulating means, organic insulating means, and inorganic polymer insulating means.

4. The bipolar electroluminescent device according to claim 3 with said insulating means being an organic insulating means.

5. The bipolar electroluminescent device according to claim 4 wherein said organic insulating means is selected from the group of organic insulating means consisting of conjugated polymers, acrylic polymers, nylon polymers, polyvinylcarbazoles, copolymers thereof, organic insulating molecules, and mixtures thereof.

6. The bipolar electroluminescent device according to claim 5 with said organic insulating means being a conjugated polymer.

7. The bipolar electroluminescent device according to claim 6 with said conjugated polymer being a polyaniline polymer.

8. The bipolar electroluminescent device according to claim 7 with said polyaniline polymer being a polyaniline emeraldine base.

9. The bipolar electroluminescent device according to claim 5 with said organic insulating means being an organic insulating molecule.

10. The bipolar electroluminescent device according to claim 9 with said organic insulating molecule being dispersed in a host polymer.

11. The bipolar electroluminescent device according to claim 10 with said insulating organic molecule being 2-(4-biphenyl)-5-(4-tert-butylphenyl-1,3,4-oxadiazole).

12. The bipolar electroluminescent device according to claim 10 with said host polymer being emeraldine base.

13. The bipolar electroluminescent device according to claim 11 with said host polymer being emeraldine base.

14. The bipolar electroluminescent device according to claim 10 with said host polymer being polyvinylcarbazole.

15. The bipolar electroluminescent device according to claim 11 with said host polymer being polyvinylcarbazole.

16. The bipolar electroluminescent device according to claim 5 with said organic insulating means being an acrylic polymer.

17. The bipolar electroluminescent device according to claim 16 with said acrylic polymer being polymethylmethacrylate.

18. The bipolar electroluminescent device according to claim 3 with said insulating means being a ceramic insulating means.

19. The bipolar electroluminescent device according to claim 18 with said ceramic insulating means being aluminum oxide.

20. The bipolar electroluminescent device according to claim 1 wherein said insulating means is at least partially transparent.

21. The bipolar electroluminescent device according to claim 1 wherein said electroluminescent organic light-emitting means is selected from the group of organic light-emitting means consisting of electroluminescent organic light-emitting molecules and electroluminescent organic light-emitting polymers.

22. The bipolar electroluminescent device according to claim 21 with said electroluminescent organic light-emitting means being an electroluminescent organic light-emitting polymer.

23. The bipolar electroluminescent device according to claim 22 wherein said electroluminescent organic light-emitting polymer is a polymer selected from the group of electroluminescent polymers consisting of polypyridines, polypyridylvinylenes, polyphenylenes, polyphenylenevinylenes, polythiophenes, polyvinylcarbazoles, polyfluorenes, polynaphthalenevinylenes, polyphenyleneacetylenes, polyphenylenediacetylenes, polycyanoterephthalylidenes, polyphenylenebenzobisthiazoles, polybenzimidazobenzophenanthrolines, copolymers thereof, and mixtures thereof.

24. The bipolar electroluminescent device according to claim 23 with said electroluminescent polymer being a polypyridine.

25. The bipolar electroluminescent device according to claim 24 with said polypyridine being poly(p-pyridine).

26. The bipolar electroluminescent device according to claim 23 with said electroluminescent organic polymer being a copolymer.

27. The bipolar electroluminescent device according to claim 26 wherein said electroluminescent copolymer is poly(phenylenevinylene pyridylvinylene).

28. The bipolar electroluminescent device according to claim 23 with said electroluminescent organic polymer being an electroluminescent polyphenylene.

29. The bipolar electroluminescent device according to claim 23 with said electroluminescent organic polymer being a polyphenylenevinylene.

30. The bipolar electroluminescent device according to claim 29 with said electroluminescent polyphenylenevinylene being poly(p-phenylenevinylene).

31. The bipolar electroluminescent device according to claim 23 with said electroluminescent organic polymer being a polyphenylenebenzobisthiazole.

32. The bipolar electroluminescent device according to claim 1 with at least one of said first electrode means and said second electrode means being an electrode means that is at least partially transparent.

33. The bipolar electroluminescent device according to claim 1 with at least one of said first electrode means and said second electrode means being an electrode means selected from the group of electrode means consisting of In--SnO₂, metals, alloys, conducting non-metals, and highly conducting organic polymers.

34. The bipolar electroluminescent device according to claim 33 with said electrode means being In--SnO₂.

35. The bipolar electroluminescent device according to claim 1 further comprising a substrate in contact with one of said first electrode means and said second electrode means.

36. The bipolar electroluminescent device according to claim 35 wherein said substrate is at least partially transparent.

37. The bipolar electroluminescent device according to claim 35 with said substrate being electrically non-conducting.

38. The bipolar electroluminescent device according to claim 35 wherein said substrate is selected from the group of substrates consisting of glass and plastic.

39. The bipolar electroluminescent device according to claim 38 with said substrate being glass.

40. The bipolar electroluminescent device according to claim 39 with said electrode means contacting said substrate being In--SnO₂.

41. The bipolar electroluminescent device according to claim 1 having a turn-on voltage of less than about 24 volts.

42. The bipolar electroluminescent device according to claim 1 having a turn-on voltage of less than about 12 volts.

43. The bipolar electroluminescent device according to claim 1 having a turn-on voltage of less than about 6 volts.

44. The bipolar electroluminescent device according to claim 1 having modulated light output.

45. The bipolar electroluminescent device according to claim 44 having frequency modulated light output.

46. The bipolar electroluminescent device according to claim 44 having amplitude modulated light output.

47. The bipolar electroluminescent device according to claim 1 wherein said light emitter is a mixture of said light emitting means and said electrical insulating means.

48. The bipolar electroluminescent device according to claim 47 wherein said potential difference is an alternating potential difference.

49. The bipolar electroluminescent device according to claim 47 with said electrical insulating means comprising an electrically insulating organic polymer.

50. The bipolar electroluminescent device according to claim 49 with said electrically insulating organic polymer being a nylon.

51. The bipolar electroluminescent device according to claim 50 with said electrically insulating organic nylon polymer being formed from adipic acid and 1,6-hexanediamine.

52. The bipolar electroluminescent device according to claim 49 with said electrically insulating organic polymer being polymethylmethacrylate.

53. The bipolar electroluminescent device according to claim 47 with said electroluminescent organic light emitting means being an electroluminescent organic light-emitting polymer.

54. The bipolar electroluminescent device according to claim 53 with said electroluminescent organic light emitting polymer being a polypyridine.

55. The bipolar electroluminescent device according to claim 54 with said electroluminescent organic light emitting polypyridine being poly(p-pyridine).

56. The bipolar electroluminescent device according to claim 53 with said electroluminescent organic light emitting polymer being a polyphenylenevinylene.

57. The bipolar electroluminescent device according to claim 53 with said electroluminescent organic light emitting polymer being a polypyridylvinylene.

58. The bipolar electroluminescent device according to claim 1 wherein said light emitter is formed as a layer of said light emitting means in contact with a layer of said electrical insulating means and said first electrode means is in contact with said electrical insulating means and said second electrode means is in contact with said light emitting means and said second electrode means has a lower electron work function than said first electrode means.

59. The bipolar electroluminescent device according to claim 58 wherein said potential difference is an alternating potential difference.

60. The bipolar electroluminescent device according to claim 58 with said electrical insulating means comprising an electrically insulating organic polymer.

61. The bipolar electroluminescent device according to claim 60 with said electrically insulating organic polymer being an insulating polyaniline.

62. The bipolar electroluminescent device according to claim 61 with said electrically insulating organic polyaniline polymer being emeraldine base.

63. The bipolar electroluminescent device according to claim 60 with said electrically insulating organic polymer being polymethylmethacrylate.

64. The bipolar electroluminescent device according to claim 58 with said electrically insulating means being a mixture of insulating emeraldine base and 2-(4-biphenyl)-5-(4-tertbutylphenyl-1,3,4-oxadiazole.

65. The bipolar electroluminescent device according to claim 58 with said electroluminescent organic light emitting means being an electroluminescent organic light-emitting polymer.

66. The bipolar electroluminescent device according to claim 65 with said electroluminescent organic light emitting polymer being a polypyridine.

67. The bipolar electroluminescent device according to claim 65 with said polypyridine being poly(p-pyridine).

68. The bipolar electroluminescent device according to claim 65 with said electroluminescent organic light emitting polymer being polyphenylenevinylene.

69. The bipolar electroluminescent device according to claim 65 with said electroluminescent organic light emitting polymer being a polypyridylvinylene.

70. The bipolar electroluminescent device according to claim 58 wherein said first electrode means is indium tin oxide and said second electrode means is aluminum.