High efficiency solid state light-emitting device and method of generating light

• US 6,630,793 B2
• Filed: 08/14/2001
• Issued: 10/07/2003
• Est. Priority Date: 08/16/2000
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Rudmann, Hartmut, Rubner, Michael F.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): TRAN, THUY V
• Application Number:
  US09/928,515
• Publication Number:
  US 20020047551A1
• Time in Patent Office: 784 Days
• Field of Search: 315/169.2, 315/169.1, 315/169.3, 315/246, 313/483, 428/917
• US Class Current: 315/169.1
• CPC Class Codes: H10K 50/135 comprising mobile ions
• CPC Class Codes: H10K 71/30 Doping active layers, e.g. electron transporting layers
• CPC Class Codes: H10K 85/141 comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE
• CPC Class Codes: H10K 85/341 Transition metal complexes, e.g. Ru(II)polypyridine complexes H10K85/331 takes precedence
• CPC Class Codes: H10K 85/344 comprising ruthenium

Abstract

A solid state electrochemical light-emitting device has a high maximum luminance, a high external efficiency, a long half-life, and a low operating voltage. The device includes a solid layer of metal complex distributed in a polymer matrix. The solid layer is contacted by electrodes on each surface. An applied potential across the electrodes generates light with a luminance of at least 30 cd/m². The light-emitting device can have external quantum efficiencies of at least 2.0%. A light-emitting circuit including an AC voltage waveform generator coupled to the electrodes of the device is also described.

Claims

1. A solid state electrochemical light-emitting device comprising:

a solid layer including a non-polymeric metal complex distributed in a polymer matrix, the solid layer having a first surface and a second surface;

a first electrode in contact with the first surface; and

a second electrode in contact with the second surface.

2. The device of claim 1, wherein the non-polymeric metal complex is a transition metal complex.

3. The device of claim 1, wherein the device has an external efficiency of at least 1.0 percent at a luminance of at least 100 cd/m².

4. The device of claim 1, wherein the device has an external efficiency of at least 4.0 percent at a luminance of at least 30 cd/m².

5. The device of claim 1, wherein the device has a time for an intensity of the device to decrease to one-half of a maximum intensity under a 50% duty cycle at 5 V and 1 kHz of at least 200 hours.

6. The device of claim 1, wherein the device has a time for an intensity of the device to decrease to one-half of a maximum intensity under a 50% duty cycle at 5 V and 1 kHz of at least 400 hours.

7. The device of claim 1, wherein the non-polymeric metal complex is a ruthenium complex.

8. The device of claim 7, wherein the metal complex is a hexafluorophosphate salt of a ruthenium bipyridine complex.

9. The device of claim 8, wherein the second electrode is selected from a group consisting of indium tin oxide, silver, gold, platinum, palladium, and polypyrrole.

10. The device of claim 1, wherein the non-polymeric metal complex is a metal bipyridine complex.

11. The device of claim 10, wherein the bipyridine has a C1-C18 alkyl subtituent.

12. The device of claim 10, wherein the bipyridine has a tert-butyl substituent.

13. The device of claim 1, wherein the first electrode is selected from a group consisting of indium tin oxide, aluminum, silver, gold, platinum, and palladium.

14. The device of claim 1, wherein the first electrode is silver and the second electrode is indium tin oxide.

15. The device of claim 1, wherein the polymer matrix includes a polymethylmethacrylate, a polystyrene or a polycarbonate.

16. A solid state electrochemical light-emitting device comprising:

a solid layer including a non-polymeric metal bipyridine complex distributed in a polymer matrix,

an indium tin oxide electrode in contact with a first surface of the solid layer; and

a silver electrode in contact with a second surface of the solid layer.

17. The device of claim 16, wherein the device has a time for an intensity of the device to decrease to one-half of a maximum intensity under a 50% duty cycle at 5 V and 1 kHz of at least 200 hours.

18. The device of claim 16, wherein the device has an external efficiency of at least 1.0 percent at a luminance of at least 100 cd/m².

19. A solid state light-emitting circuit comprising:

a solid state electrochemical light-emitting device comprising;

(1) a solid layer including a metal complex, the solid layer having a first surface and a second surface;

(2) a first electrode in contact with the first surface; and

(3) a second electrode in contact with the second surface; and

a driver comprising an AC voltage waveform generator configured to apply an AC voltage waveform across first electrode and the second electrode, whereby the solid state light-emitting device emits light.

20. The circuit of claim 19, wherein the driver further comprises a DC voltage generator configured to apply a DC voltage across first electrode and the second electrode.

21. The circuit of claim 19, wherein the metal complex is a non-polymeric transition metal complex.

22. The circuit of claim 19, wherein the device has an external efficiency of at least 1.0 percent at a luminance of at least 100 cd/m².

23. The circuit of claim 19, wherein the device has a time for an intensity of the device to decrease to one-half of a maximum intensity under a 50% duty cycle at 5 V and 1 kHz of at least 200 hours.

24. The circuit of claim 19, wherein the metal complex is a non-polymeric ruthenium complex.

25. The circuit of claim 19, wherein the metal complex is a hexafluorophosphate salt of a non-polymeric ruthenium bipyridine complex.

26. The circuit of claim 19, wherein the first electrode is selected from a group consisting of indium tin oxide, aluminum, silver, gold, platinum, and palladium.

27. The circuit of claim 26, wherein the second electrode is selected from a group consisting of indium tin oxide, silver, gold, platinum, palladium, and polypyrrole.

28. The circuit of claim 19, wherein the first electrode is silver and the second electrode is indium tin oxide.

29. The circuit of claim 19, wherein the polymer matrix includes a polymethylmethacrylate, a polystyrene or a polycarbonate.

30. A method of generating light comprising:

applying a light-generating potential across a first electrode and a second electrode of a solid state electrochemical light-emitting device including a solid layer including a non-polymeric metal complex distributed in a polymer matrix, the solid layer having a first surface and a second surface, the first electrode contacting the first surface, and the second electrode contacting with the second surface; and

generating light from the device having a luminance of at least 30 cd/m².

31. The method of claim 30, wherein applying a light-generating potential comprises applying a DC voltage across the first electrode and the second electrode for a predetermined period of time, and applying an AC voltage waveform across the first electrode and the second electrode after the predetermined period of time.

32. The method of claim 30, wherein the metal complex is a non-polymeric transition metal complex.

33. The method of claim 30, wherein the device has an external efficiency of at least 1.0 percent at a luminance of at least 100 cd/m².

34. The method of claim 30, wherein the metal complex is a non-polymeric ruthenium complex.

35. The method of claim 30, wherein the metal complex is a hexafluorophosphate salt of a non-polymeric ruthenium bipyridine complex.

36. The method of claim 30, wherein the first electrode is selected from a group consisting of indium tin oxide, aluminum, silver, gold, platinum, and palladium.

37. The method of claim 36, wherein the second electrode is selected from a group consisting of indium tin oxide, silver, gold, platinum, palladium, and polypyrrole.

38. The method of claim 30, wherein the first electrode is silver and the second electrode is indium tin oxide.

39. The method of claim 30, wherein the AC voltage waveform is a square wave.

40. The method of claim 39, wherein the AC voltage waveform is a 50% duty cycle.

41. The method of claim 40, wherein the device has a time for an intensity of the device to decrease to one-half of a maximum intensity under a 50% duty cycle at 5 V and 1 kHz of at least 200 hours.

42. A method of manufacturing a solid state electrochemical light-emitting device comprising:

depositing a solid layer including a non-polymeric metal complex distributed in a polymer matrix onto a first electrode; and

placing a second electrode onto the solid layer,

wherein the device has an external efficiency of at least 1.0 percent at a luminance of at least 30 cd/m².