Quantum dot films, lighting devices, and lighting methods

• US 9,199,842 B2
• Filed: 11/02/2011
• Issued: 12/01/2015
• Est. Priority Date: 12/30/2008
• Status: Active Grant

• Current Assignee: Shoei Chemical Inc.
• Original Assignee: Nanosys Incorporated (Shoei Electronic Materials, Inc.)
• Inventors: Dubrow, Robert S., Freeman, William P., Lee, Ernest, Furuta, Paul
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): APENTENG, JESSICA MCMILLAN
• Application Number:
  US13/287,616
• Publication Number:
  US 20120113672A1
• Time in Patent Office: 1,490 Days
• Field of Search: 362/606, 362/612, 362/602, 362230-235, 362/84, 313/502, 349/68
• US Class Current: 1/1
• CPC Class Codes: B32B 2313/00 Elements other than metals
• CPC Class Codes: B32B 2457/202 LCD, i.e. liquid crystal displays
• CPC Class Codes: B32B 2551/00 Optical elements
• CPC Class Codes: B32B 5/16 characterised by features of a layer formed of particles, e.g. chips, powder or granules layer formed of natural mineral particles B32B19/00; layer being formed of wood fibres, chips or particles B32B21/02
• CPC Class Codes: B32B 9/04 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material next to a glass layer B32B17/06; layered products with at least two ceramic layers composed mainly of ceramic B32B18/00
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: F21V 9/30 Elements containing photoluminescent material distinct from or spaced from the light source shades F21V1/17; globes, bowls or cover glasses F21V3/08, F21V3/12; refractors F21V5/10; reflectors F21V7/26, F21V7/30; elements with provision for controlling the spectral properties or intensity F21V9/40
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: Y10S 977/774 Exhibiting three-dimensional carrier confinement, e.g. quantum dots
• CPC Class Codes: Y10T 428/31504 Composite [nonstructural laminate]

Abstract

Light-emitting quantum dot films, quantum dot lighting devices, and quantum dot-based backlight units are provided. Related compositions, components, and methods are also described. Improved quantum dot encapsulation and matrix materials are provided. Quantum dot films with protective barriers are described. High-efficiency, high brightness, and high-color purity quantum dot-based lighting devices are also included, as well as methods for improving efficiency and optical characteristics in quantum dot-based lighting devices.

Claims

1. A display backlighting unit (BLU), comprising:

at least one primary light source that emits primary light;

a light guide panel (LGP) optically coupled to the at least one primary light source, whereby the primary light is transmitted uniformly through the LGP;

a remote phosphor film disposed over the LGP, wherein the primary light transmits uniformly through the LGP and into the remote phosphor film; and

a first barrier film and a second barrier film, wherein the first and second barrier films are each disposed adjacent the remote phosphor film and on opposite sides thereof, and

wherein the remote phosphor film is not directly physically coupled to the LGP and comprises only two populations of light emitting quantum dots (ODs) including a first population of QDs configured to emit first secondary light and a second population of QDs configured to emit second secondary light at a different wavelength than the first secondary light, whereby at least a portion of the primary light is absorbed by the two populations of QDs and reemitted by the QDs as the first and second secondary light.

2. A display backlighting unit (BLU), comprising:

at least one primary light source that emits primary light;

a light guide panel (LGP) optically coupled to the at least one primary light source, whereby the primary light is transmitted uniformly through the LGP; and

a remote phosphor film, sandwiched between at least two barrier layers, comprising only two populations of light emitting quantum dots (QDs) including a first population of QDs configured to emit first secondary light and a second population of QDs configured to emit second secondary light at a different wavelength than the first secondary light;

wherein the remote phosphor film is not directly phy the LGP, wherein the primary light transmits uniformly through the LGP and into the remote phosphor film, whereby at least a portion of the primary light is absorbed by the two populations of QDs and reemitted by the QDs as the first and second secondary light.

3. The display BLU of claim 2, wherein the display is a liquid crystal display (LCD).

4. The display BLU of claim 3, wherein the remote phosphor film is a flat film covering an entire viewing plane surface area of the LCD.

5. The display BLU of claim 2, wherein the remote phosphor film is disposed directly adjacent the LGP.

6. The display BLU of claim 2, further comprising a reflector film beneath the LGP, wherein the reflector film reflects primary light toward the QDs in the remote phosphor film.

7. The display BLU of claim 2, further comprising one or more diffuser layers or light extraction layers at the bottom surface of the LGP, at the top surface of the LGP, or at the bottom and top surfaces of the LGP, whereby the one or more diffuser layers or light extraction layers reflects or refracts primary light toward the remote phosphor film above the LGP.

8. The display BLU of claim 2, further comprising one or more brightness enhancing films (BEFs), wherein the remote phosphor film is disposed above the LGP and the one or more BEFs are disposed above the remote phosphor film, wherein a first portion of the primary light transmits through the one or more BEFs and a second portion of the primary light is reflected toward the remote phosphor film by the one or more BEFs.

9. The display BLU of claim 8, wherein the BLU comprises at least two BEFs.

10. The display BLU of claim 2, wherein the remote phosphor film comprises a QD phosphor material film comprising at least one QD phosphor material film layer comprising at least one matrix material, wherein the QDs are embedded in the at least one matrix material.

11. The display BLU of claim 10, wherein the at least one QD phosphor material film layer comprises the QDs embedded in an epoxy matrix material, wherein the QDs are coated with an amino polystyrene (APS) ligand material and embedded in the epoxy matrix material.

12. The display BLU of claim 10, wherein the at least one QD phosphor material film layer comprises the QDs embedded in an epoxy matrix material, wherein the QDs are coated with a polyethyleneimine or modified polyethyleneimine ligand material and embedded in the epoxy matrix material.

13. The display BLU of claim 10, further comprising one or more mar light scattering features that scatter primary light toward the QDs.

14. The display BLU of claim 13, wherein the scattering features increase the primary light optical path length in the remote phosphor film, thereby increasing the amount of primary light absorbed by the QDs and reemitted as secondary light.

15. The display BLU of claim 13, wherein at least a portion of the primary light scattered by the scattering features is subsequently absorbed by the QDs and reemitted as secondary light.

16. The display BLU of claim 13, wherein at least a portion of the scattering features are disposed below at least a portion of the QDs, such that at least a portion of the scattering features are disposed between at least a portion of the QDs and the at least one primary light source.

17. The display BLU of claim 13, wherein at least a portion of the scattering features are disposed in the same layer as at least a portion of the QDs.

18. The display BLU of claim 13, wherein a majority of the scattering features are disposed either in the same layer as the QDs or below the QDs.

19. The display BLU of claim 13, wherein the one or more primary light scattering features are disposed within one or more layers of the QD phosphor material film.

20. The display BLU of claim 13, wherein the one or more primary light scattering features are disposed between multiple layers of the QD phosphor material film.

21. The display BLU of claim 13, wherein the one or more primary light scattering features and the QDs are dispersed uniformly throughout the QD phosphor material film.

22. The display BLU of claim 13, wherein the one or more primary light scattering features are dispersed between the QD phosphor material film and one or more barrier films.

23. The display BLU of claim 13, wherein the at least one bottom barrier film comprises a first barrier film and at least a second barrier film, wherein the one or more primary light scattering features are dispersed between the first barrier film and at least the second barrier film.

24. The display BLU of claim 13, wherein the at least one top barrier film comprises a first barrier film and at least a second barrier film, wherein the one or more primary light scattering features are dispersed between the first barrier film and at least the second barrier film.

25. The display BLU of claim 13, wherein the one or more primary light scattering features comprise scattering particles.

26. The display BLU of claim 25, wherein the scattering particles comprise spherical scattering beads.

27. The display BLU of claim 26, wherein the scattering beads comprise silica, borosilicate, or polystyrene beads.

28. The display BLU of claim 26, wherein the scattering particles comprise spherical beads having a diameter between about 0.5 μ

m and about 2 μ

m, a diameter of about 0.5 μ

m, or a diameter of about 1 μ

m.

29. The display BLU of claim 25, wherein the QD phosphor material film consists of about 1% to about 15% scattering particles by volume, about 2% to about 10% scattering particles by volume, or about 5% scattering particles by volume.

30. The display BLU of claim 25, wherein the scattering particles are disposed in a layer below the QDs, between the LGP and the QDs.

31. The display BLU of claim 13, wherein the scattering beads are embedded in the matrix material and have an index of refraction higher than that of the surrounding matrix material.

32. The display BLU of claim 31, wherein the scattering particles have a refractive index of about 2 or greater, greater than 2, or about 2.

33. The display BLU of claim 13, wherein the primary light scattering features comprise voids.

34. The display BLU of claim 13, wherein the primary light scattering features comprise hollow beads.

35. The display BLU of claim 13, wherein the QD phosphor material film comprises a first matrix material having a first refractive index and at least a second matrix material having a second refractive index different than the first refractive index, wherein the primary light scattering features comprise scattering domains comprising domains of the second matrix material dispersed within the first matrix material.

36. The display BLU of claim 35, wherein the scattering domains have a dimension between about 0.5 μ

m and about 2 μ

m, about 0.5 μ

m, or a about 1 μ

m.

37. The display BLU of claim 35, wherein the first matrix material has a refractive index which is less than 2, and the second material has a refractive index of about 2 or greater, greater than 2, or about 2.

38. The display BLU of claim 35, wherein the first material comprises an epoxy and the second material has a refractive index of about 2 or greater, greater than 2, or about 2.

39. The display BLU of claim 35, wherein the first material comprises a transparent glass or polymer material and the second material comprises air.

40. The display BLU of claim 13, wherein the scattering features comprise a population of light emitting QDs which absorb primary light and emit blue light.

41. The display BLU of claim 13, wherein the scattering features are formed on a surface of at least one said barrier film.

42. The display BLU of claim 13, wherein the scattering features are formed on at least one surface of at least one barrier film, which barrier film surface directly contacts the QD phosphor material film.

43. The display BLU of claim 13, wherein the scattering features comprise a primary light scattering surface pattern formed on a surface of at least one said barrier film, wherein the pattern comprises micro-textures, prisms, pitches, pyramids, grooves, lenses, bumps, waves, scratches, or domes.

44. The display BLU of claim 13, wherein the scattering features comprise a primary light scattering surface pattern formed on a surface of the LGP.

45. The display BLU of claim 44, wherein the pattern comprises a random micro-textured pattern, prisms, pitches, lenses, bumps, waves, scratches, or domes.

46. The display BLU of claim 13, wherein the scattering features have a size of about 5 μ

m or less, about 2 μ

m or less, about 1.5 μ

m or less, about 1 μ

m or less, or about 0.5 μ

m or less.

47. The display BLU of claim 13, wherein the remote phosphor film comprising QDs and scattering features is a combination diffuser and phosphor film, thereby reducing or eliminating the need for separate phosphor and diffuser films in the display BLU.

48. The display BLU of claim 13, wherein the QD phosphor material film comprises:

a first film layer comprising a first population of QDs which emit red secondary light, a second film layer comprising a second population of QDs which emit green secondary light, and at least one population of scattering particles disposed in one or more of the first film layer, the second film layer, a third film layer distinct from the first and second film layers.

49. The display BLU of claim 13, wherein the scattering features comprise scattering particles embedded in at least one said bottom barrier film.

50. The display BLU of claim 13, wherein the scattering features comprise particles dispersed in the at least one QD phosphor material film layer, wherein the scattering particles have a density close to that of the QD phosphor material.

51. The display BLU of claim 13, wherein the QD phosphor material is sealed between the barrier films, wherein the seal comprises an end seal, a hermetic seal, or a combination thereof.

52. The display BLU of claim 13, wherein the QD phosphor material is sealed between the barrier films, wherein the perimeter edges of the barrier films are pinch-sealed or frit-sealed.

53. The display BLU of claim 13, wherein the QD phosphor material comprises an inactive region around the perimeter of the remote phosphor film.

54. The display BLU of claim 53, wherein the inactive region has a width of about 1 mm, about 1 min or less, or less than 1 mm.

55. The display BLU of claim 13, wherein each of the barrier films comprises a transparent material comprising a glass, a polymer, or a polymer film coated with an oxide layer.

56. The display BLU of claim 13, wherein at least one of the top and bottom barrier films comprises at least two barrier films having a vacuum or gas-filled gap sealed between the at least two barrier films.

57. The display BLU of claim 13, wherein the scattering features comprise surface patterns formed on at least one surface of at least one of said barrier films.

58. The display BLU of claim 57, wherein the pattern comprises micro-textures, prisms, pitches, pyramids, grooves, lenses, bumps, waves, scratches, or domes.

59. The display BLU of claim 57, wherein the scattering features have a size of about 5 μ

m or less, about 2 μ

m or less, about 1.5 μ

m or less, about 1 μ

m or less, or about 0.5 μ

m or less.

60. The display BLU of claim 57, wherein the scattering features are formed on at least one surface of at least one of said barrier films, which barrier film surface directly contacts the QD phosphor material film.

61. The display BLU of claim 13, wherein the scattering features comprise scattering particles embedded in at least one said bottom barrier film.

62. The display BLU of claim 13, wherein the scattering features are dispersed uniformly in the QD phosphor material.

63. The display BLU of claim 13, wherein at least a portion of the scattering features are disposed in the same QD phosphor material layer as at least a portion of the QDs.

64. The display BLU of claim 13, wherein at least a portion of the scattering features are disposed between at least a first portion of the QDs and at least a second portion of the QDs.

65. The display BLU of claim 13, wherein at least a portion of the scattering features are disposed below at least a portion of the QDs, such that at least a portion of the scattering features are disposed between at least a portion of the QDs and the at least one bottom barrier film.

66. The display BLU of claim 13, wherein the scattering features are disposed below the QDs, wherein the scattering features are disposed between the QDs and the at least one bottom barrier.

67. The display BLU of claim 13, wherein at least a portion of the scattering features are disposed above at least a portion of the QDs, such that at least a portion of the scattering features are disposed between at least a portion of the QDs and the at least one top barrier film.

68. The display BLU of claim 13, wherein the scattering features are disposed above the QDs, wherein the scattering features are disposed between the QDs and the at least one top barrier.

69. The display BLU of claim 13, wherein the at least one bottom barrier film comprises two or more bottom barrier films, and the scattering features are disposed between two or more said bottom barrier films.

70. The display BLU of claim 13, wherein the top barrier film comprises two or more bottom barrier films, and the scattering features are disposed between two or more said top barrier films.

71. The display BLU of claim 13, wherein the QD phosphor material comprises a first QD phosphor material layer comprising the first population of QDs, and a second QD phosphor material layer comprising the second population of QDs, wherein the scattering features are disposed in one or more of the first QD phosphor material layer, the second QD phosphor material layer, and a third QD phosphor material layer which is distinct from the first and second layers.

72. The display BLU of claim 71, wherein the scattering features are disposed in a third QD phosphor material layer which is distinct from the first and second layers, wherein the third layer is disposed above the first and second layers, below the first and second layers, or between the first and second layers.

73. The display BLU of claim 13, wherein each of the barrier films comprises a polymer film coated with an oxide layer.

74. The display BLU of claim 10, wherein the QD phosphor material film has a uniform thickness over an entire viewing plane surface area of the display.

75. The display BLU of claim 10, wherein the QD phosphor material film has a thickness of 500 μ

m or less, 250 μ

m or less, 200 μ

m or less, 50-150 μ

m, 50-100 μ

m, about 100 μ

m, or about 50 μ

m.

76. The display BLU of claim 10, wherein the QD phosphor material film comprises less than about 20%, less than 20%, less than about 15%, less than 15%, less than about 10%, less than about 5%, less than 5%, less than 1%, or less than about 1% QDs by volume.

77. The display BLU of claim 10, wherein the QD phosphor material comprises a first QD phosphor material layer comprising the first population of QDs and a second QD phosphor material layer comprising the second population of QDs.

78. The display BLU of claim 10, wherein the OD phosphor material film layer comprises a first QD phosphor material layer a first concentration of QDs and a second QD phosphor material layer comprising a second concentration of QDs.

79. The display BLU of claim 10, wherein the QD phosphor material film layer comprises multiple QD phosphor material layers, wherein each layer has a different concentration of red light emitting QDs and a different concentration of green light emitting QDs.

80. The display BLU of claim 2, where in the at least one primary light source comprises one or more blue LEDs coupled to one or more surfaces of the LGP, whereby the one or more LEDs are disposed within the same plane as the LGP.

81. The display BLU of claim 2, wherein the QDs are dispersed uniformly in the QD phosphor material.

82. A display backlighting unit (BLU), comprising:

at least one primary light source that emits primary light;

a light guide panel (LGP) optically coupled to the at least one primary light source, whereby the primary light is transmitted uniformly through the LGP; and

a remote phosphor film, sandwiched between at least two barrier layers, comprising only one population of light emitting quantum dots (QDs) configured to emit first secondary light;

wherein the remote phosphor film is not directly physically coupled to the LGP, wherein the primary light transmits uniformly through the LGP and into the remote phosphor film, whereby at least a portion of the primary light is absorbed by the only one population of QDs and reemitted by the QDs as the first secondary light having a longer wavelength than the primary light.

83. The display BLU of claim 82, wherein each of the barrier films comprises a transparent material comprising a glass, a polymer, or a polymer film coated with an oxide layer.

84. The display BLU of claim 82, wherein each of the barrier films comprises a polymer film coated with an oxide layer.