Displays having mesa pixel configuration

• US 6,091,195 A
• Filed: 02/03/1997
• Issued: 07/18/2000
• Est. Priority Date: 02/03/1997
• Status: Expired due to Term

• Current Assignee: The Trustees of Princeton University (Princeton University)
• Original Assignee: The Trustees of Princeton University (Princeton University)
• Inventors: Forrest, Stephen R., Burrows, Paul, Garbuzov, Dmitri Z.
• Primary Examiner(s): DAY, MICHAEL HENRY
• Application Number:
  US08/794,595
• Time in Patent Office: 1,261 Days
• Field of Search: 313/498, 313/503, 313/504, 313/506, 313/509, 315/169.1, 315/169.3
• US Class Current: 313/504
• CPC Class Codes: H10K 50/856 comprising reflective means

Abstract

A multicolor organic light emitting display device employs angle-walled blue, green and red emitting mesas, with optional metal reflectors on the angled walls, in a plurality of pixels. The angle-walled mesas, which resemble truncated pyramids, direct light out of the mesa by reflection from the mesa side walls or by mirror reflection. The device of the present invention reduces waveguiding, thus simultaneously increasing both display brightness and resolution.

Claims

1. A display device comprising a plurality of pixels over a substrate, each of said plurality of pixels comprising:

at least one angle-walled mesa connected to said substrate, wherein each said mesa has at least two side walls each comprising a reflective layer; and

at least one OLED within each said mesa;

wherein each of said mesas includes a blue OLED as a source of light.

3. A computer incorporating the display of either of claim 1 or claim 2.

4. A television incorporating the display of either of claim 1 or claim 2.

5. A screen incorporating the display of either of claim 1 or claim 2, wherein said screen is selected from the group consisting of a wall screen, a theater screen and a stadium screen.

6. A billboard incorporating the display of either of claim 1 or claim 2.

7. A vehicle incorporating the display of either of claim 1 or claim 2.

8. A printer incorporating the display of either of claim 1 or claim 2.

9. A telecommunications device incorporating the display of either of claim 1 or claim 2.

10. A telephone incorporating the display of either of claim 1 or claim 2.

11. A sign incorporating the display of either of claim 1 or claim 2.

12. The multicolor display of claim 1 or 2, wherein light is emitted from the at least one OLED, some of which light is emitted in a direction toward at least one of said sidewalls, and wherein substantially all of the light that is emitted in said direction toward at least one of said sidewalls is reflected off of said sidewalls.

2. A display device comprising a plurality of pixels over a substrate, each of said plurality of pixels comprising:

at least one angle-walled mesa connected to said substrate, wherein each said mesa has at least two side walls each comprising a reflective layer; and

at least one OLED on each said mesa.

13. An electronic device incorporating a display device comprising a plurality of pixels over a substrate, each of said plurality of pixels comprising:

at least one angle-walled mesa connected to said substrate, wherein each mesa has two side walls each comprising a reflective layer; and

at least one OLED within each said mesa.

14. An electronic device incorporating a display device comprising a plurality of pixels over a substrate, each of said plurality of pixels comprising:

at least one angle-walled mesa connected to said substrate, wherein each mesa has at least two side walls each comprising a reflective layer; and

at least one OLED on each said mesa.

15. A multicolor display comprising a plurality of pixels over a substrate, each or said plurality of pixels comprising:

at least one angle-walled mesa connected to said substrate, each of said mesas comprising a top portion and a bottom portion, the top portion being narrow relative to the bottom portion, the bottom portion being connected to the substrate;

wherein each angle-walled mesa has at least two side walls each comprising a reflective layer.

16. A method of using a display device comprising a plurality of pixels over a substrate, each of said plurality of pixels comprising a) at least one angle-walled mesa connected to said substrate wherein each mesa has at least two side walls each comprising a reflective layer, a top end and a bottom end, where the top end is narrower than the bottom end and the bottom end is connected to said substrate, and b) at least one OLED within each said mesa, comprising

applying an electric current across said at least one OLED to cause said at least one OLED to emit light.

17. A multicolor display comprising a plurality of pixels over a substrate, each of said plurality of pixels comprising:

three angle-walled mesas connected to said substrate, each of said mesas comprising a top portion and a bottom portion, the top portion being narrow relative to the bottom portion and further from the substrate than said bottom portion, the first of said three mesas being a blue light emitter, the second of said three mesas being a green light emitter, and the third of said three mesas being a red light emitter;

wherein each of said three angle-walled mesas has at least two side walls each comprising a reflective layer.

18. The multicolor display of claim 17 wherein:

said substrate is transparent; and

the bottom portion of each of said three mesas is immediately adjacent said substrate such that the light emitted from each of said three mesas is directed towards said substrate.

19. The multicolor display of claim 18, further comprising a plurality of reflectors, one of said plurality of reflectors on each of opposing angled walls of each of said mesas.

20. The multicolor display of claim 18, wherein the first of said three mesas comprises:

a first dielectric layer on said substrate;

an anode layer on said dielectric layer;

a blue OLED layer on said anode layer; and

a reflective cathode layer on said blue OLED layer.

21. The multicolor display of claim 20, wherein the second of said three mesas comprises:

a second dielectric layer on said substrate;

a green down-conversion phosphor layer on said dielectric layer;

an anode layer on said green down-conversion phosphor layer;

a blue OLED layer on said anode layer; and

a reflective cathode layer on said layer of blue OLED.

22. The multicolor display of claim 21, wherein the third of said three mesas comprises:

a third dielectric layer on said substrate;

a green down-conversion phosphor layer on said dielectric coating layer;

a second dielectric layer on said green down-conversion phosphor layer;

a red down-conversion phosphor layer on said second dielectric layer;

an anode layer on said red down-conversion phosphor layer;

a blue OLED layer on said anode layer; and

a reflective cathode layer on said layer of blue OLED.

23. The multicolor display of claim 22, wherein said anode layer for each of said first, second and third of said mesas comprises indium-tin-oxide.

24. The multicolor display of claim 23, wherein said reflective cathode layer for each of said first, second and third of said mesas comprises a metal having a work function less than about four electron volts.

25. The multicolor display of claim 22, wherein each of the first, second and third of said three mesas further comprises a layer of third dielectric material immediately beneath said anode layer, said third dielectric material characterized by a refractive index greater than the refractive index of said anode layer.

26. The multicolor display of claim 25, wherein said anode layer comprises indium-tin-oxide, and said third dielectric material comprises titanium dioxide.

27. The multicolor display of claim 17, wherein light is emitted from each light emitter, some of which light is emitted in a direction toward at least one of said sidewalls in said light emitter, and wherein substantially all of the light that is emitted in said direction toward at least one of said sidewalls is reflected off of said sidewalls.

28. A multicolor display comprising a plurality of pixels over a substrate, each of said plurality of pixels comprising:

three angle-walled mesas connected to said substrate, each of said mesas comprising a top portion and a bottom portion, the top portion being narrow relative to the bottom portion, the first of said three mesas being a blue light emitter, the second of said three mesas being a green light emitter, and the third of said three mesas being a red light emitter;

wherein each of said three angle-walled mesas has at least two side walls each comprising a reflective layer, wherein each of said mesas includes a blue OLED as a source of light.

29. The multicolor display of claim 28, wherein said blue OLED comprises an emissive layer selected from the group consisting of trivalent metal quinolate complexes, Schiff base divalent metal complexes, metal acetylacetonate complexes, metal bidentate ligand complexes, bisphosphonates, molecular charge transfer complexes, aromatic and heterocyclic polymers and rare earth mixed chelates.

30. The multicolor display of claim 28, wherein the second of said three mesas comprises a green down-conversion phosphor layer, whereby said green phosphor converts substantially all of the blue light emitted from said blue OLED to green light.

31. The multicolor display of claim 30, wherein said green down-conversion phosphor layer comprises at least one polymethine fluorescent dye selected from the group consisting of cyanines, merocyanines and tri-, tetra, and polynuclear cyanines and merocyanines, oxonols, hemioxanols, styryls, merostyryls and streptocyanines.

32. The multicolor display of claim 30, wherein the third of said three mesas comprises a red down-conversion phosphor layer, whereby said red phosphor converts substantially all of the blue light emitted from said blue OLED to red light.

33. The multicolor display of claim 32, wherein the red down-conversion phosphor layer comprises at least one fluorescent dye selected from the group consisting of 4-dicyano-methylene-4H-pyrans and 4-dicyanomethylene-4H-thiopyrans.

34. The multicolor display of claim 28, wherein said blue OLED is a double heterostructure device fabricated from organic materials.

35. The multicolor display of claim 34, wherein said blue OLED comprises:

a hole transporting layer;

an emission layer formed on said hole transporting layer; and

an electron transporting layer formed on said emission layer.

36. The multicolor display of claim 28, wherein said blue OLED is a single heterostructure device fabricated from organic materials.

37. The multicolor display of claim 36, wherein said blue OLED comprises:

a hole transporting layer; and

a multifunctional layer formed on said hole transporting layer, said multifunctional layer serving as an emission layer and an electron transporting layer.

38. The multicolor display of claim 28, wherein the top portion of each of said three mesas is immediately adjacent said substrate such that the light emitted from each of said three mesas is directed in a direction away from said substrate.

39. The multicolor display of claim 38, wherein the first of said three mesas comprises:

a reflective cathode layer on said substrate;

a blue OLED layer on said reflective cathode layer;

an anode layer on said blue OLED layer; and

a first dielectric layer on said anode layer.

40. The multicolor display of claim 39, wherein the second of said three mesas comprises:

a reflective cathode layer on said substrate;

a blue OLED layer on said reflective cathode layer;

an anode layer on said blue OLED layer;

a first dielectric layer on said anode layer; and

a green down-conversion phosphor layer on said dielectric layer.

41. The multicolor display of claim 40, wherein the third of said three mesas comprises:

a reflective cathode layer on said substrate;

a blue OLED layer on said reflective cathode layer;

an anode layer on said blue OLED layer;

a first dielectric layer on said anode layer; and

a red down-conversion phosphor layer on said dielectric layer.

42. The multicolor display of claim 41, wherein said anode layer for each of said first, second and third of said mesas comprises indium-tin-oxide.

43. The multicolor display of claim 41, wherein said reflective cathode layer for each of said first, second and third of said mesas comprises a metal having a work function less than about four electron volts.

44. The multicolor display of claim 41, wherein each of the first, second and third of said three mesas further comprises a layer of second dielectric material between said anode layer and said first dielectric layer, said second dielectric material characterized by a refractive index greater than the refractive index of said anode layer.

45. The multicolor display of claim 44, wherein said anode layer comprises indium-tin-oxide, and said second dielectric material comprises titanium dioxide.

46. In a multicolor display having a plurality of pixels over a substrate, each of said plurality of pixels includes:

three angle-walled mesas on said substrate, each of said mesas characterized by a top portion and a bottom portion, the top portion being narrow relative to the bottom portion, the bottom portion of each of said three mesas being immediately adjacent said substrate such that the light emitted from each of said three mesas is directed towards said substrate;

the first of said three mesas being a blue light emitter and comprising, from bottom to top, a dielectric layer on said substrate, an anode layer on said dielectric layer, a blue OLED layer on said anode layer, and a reflective cathode layer on said blue OLED layer;

the second of said three mesas being a green light emitter and comprising, from bottom to top, a dielectric layer on said substrate, a green down-conversion phosphor layer on said dielectric layer, an anode layer on said green down-conversion phosphor layer, a blue OLED layer on said anode layer, and a reflective cathode layer on said layer of blue OLED; and

the third of said three mesas being a red light emitter and comprising, from bottom to top, a dielectric layer on said substrate, a green down-conversion phosphor layer on said dielectric coating layer, a second dielectric layer on said green down-conversion layer, a red down-conversion phosphor layer on said second dielectric layer, an anode layer on said red down-conversion phosphor layer, a blue OLED layer on said anode layer, and a reflective cathode layer on said layer of blue OLED.

47. In a multicolor display having a plurality of pixels over a substrate, each of said plurality of pixels includes:

three angle-walled mesas on said substrate, each of said mesas characterized by a top portion and a bottom portion, the top portion being narrow relative to the bottom portion, the top portion of each of said mesas being immediately adjacent said substrate such that the light emitted from each of said three mesas is directed in a direction away from said substrate;

the first of said three mesas being a blue light emitter and comprising, from top to bottom, a reflective cathode layer on said substrate, a blue OLED layer on said reflective cathode layer, an anode layer on said blue OLED layer, and a dielectric layer on said anode layer;

the second of said three mesas being a green light emitter and comprising, from top to bottom, a reflective cathode layer on said substrate, a blue OLED layer on said reflective cathode layer, an anode layer on said blue OLED layer, a dielectric layer on said anode layer, and a green down-conversion phosphor layer on said dielectric layer; and

the third of said three mesas being a red light emitter and comprising, from top to bottom, a reflective cathode layer on said substrate, a blue OLED layer on said reflective cathode layer, an anode layer on said blue OLED layer, a dielectric layer on said anode layer, and a red down-conversion phosphor layer on said dielectric layer.

48. In a multicolor display having a plurality of pixels over a substrate, each of said plurality of pixels includes:

an angle-walled mesa on said substrate, said mesa characterized by a top portion and a bottom portion, the top portion being narrow relative to the bottom portion, the bottom portion being immediately adjacent said substrate such that the light emitted from said mesa is directed towards said substrate;

wherein said mesa comprises, from bottom to top, a first layer of conductive material, a blue OLED layer on said first layer of conductive material, a second layer of conductive material on said blue OLED layer, a green OLED layer on said second layer of conductive material, a third layer of conductive material on said green OLED layer, a red OLED layer on said third layer of conductive material, and a fourth layer of conductive material on said red OLED layer.

49. In a multicolor display having a plurality of pixels over a substrate, each of said plurality of pixels includes:

an angle-walled mesa on said substrate, said mesa characterized by a top portion and a bottom portion, the top portion being narrow relative to the bottom portion, the top portion of said mesa being immediately adjacent said substrate such that the light emitted from said mesa is directed in a direction away from said substrate;

wherein said mesa comprises, from top to bottom, a first layer of conductive material, a red OLED layer on said first layer of conductive material, a second layer of conductive material on said red OLED layer, a green OLED layer on said second layer of conductive material, a third layer of conductive material on said green OLED layer, a blue OLED layer on said third layer of conductive material, and a fourth layer of conductive material on said blue OLED layer.

50. A method of using a display device comprising a plurality of pixels over a substrate, each of said plurality of pixels comprising at least one angle-walled mesa connected to said substrate, and at least one OLED within each said mesa, at least one of which is a blue OLED, wherein each mesa has at least two side walls each comprising a reflective layer, said method comprising the step of applying an electric current across said at least one blue OLED to cause said at least one blue OLED to emit light.

51. A method of using a display device comprising a plurality of pixels over a substrate, each of said plurality of pixels comprising at least one angle-walled mesa connected to said substrate, and at least one OLED on each said mesa, wherein each mesa has at least two side walls each comprising a reflective layer, said method comprising the step of applying an electric current across said at least one OLED to cause said at least one OLED to emit light.

52. A method of using a display device comprising a plurality of pixels over a substrate, each of said plurality of pixels comprising three angle-walled mesas connected to said substrate, the first of said three mesas being a blue light emitter, the second of said three mesas being a green light emitter, and the third of said three mesas being a red light emitter, wherein each of said mesas includes a blue OLED as a source of light, said method comprising the step of applying an electric current across said blue OLED to cause said blue OLED to emit light, and wherein each of said mesas has at least two side walls each comprising a reflective layer.