Organic light-emitting diodes comprising grating structures and light extraction layers

1. An organic light-emitting diode (OLED), comprising:

a substrate disposed at a bottom of the OLED;

a first electrode;

a second electrode;

one or more organic layers positioned between the first electrode and the second electrode, wherein the one or more organic layers comprise a light-emitting layer; and

a light extraction layer positioned between the substrate and the first electrode, wherein a first interface between the light extraction layer and the first electrode comprises a first grating structure, wherein a refractive index of the light extraction layer is less than or equal to 1.45 and a refractive index of the first electrode is greater than or equal to 1.70, wherein the OLED is a bottom-emitting OLED, and wherein the substrate is at least partially transparent to light emitted from the light-emitting layer.

2. The OLED of claim 1 , wherein a difference between the refractive index of the light extraction layer and the refractive index of the first electrode has a magnitude of at least 0.30.

3. The OLED of claim 1 , wherein a difference between the refractive index of the light extraction layer and the refractive index of the first electrode has a magnitude between 0.20 and 1.00.

4. The OLED of claim 1 , wherein the refractive index of the light extraction layer is 1.40 or less.

5. The OLED of claim 1 , wherein the refractive index of the light extraction layer is between 1.00 and 1.45.

6. The OLED of claim 1 , wherein a difference between the refractive index of the light extraction layer and a refractive index of the substrate has a magnitude of at least 0.05.

7. The OLED of claim 1 , wherein a difference between the refractive index of the light extraction layer and a refractive index of the substrate has a magnitude between 0.05 and 1.00.

8. The OLED of claim 1 , wherein the light extraction layer comprises an inorganic material.

9. The OLED of claim 1 , wherein the light extraction layer comprises LiF, KF, and/or AlF 3 .

10. The OLED of claim 1 , wherein the light extraction layer comprises an aerogel.

11. The OLED of claim 1 , wherein the first grating structure has an average periodicity between 200 nm and 2 μm.

12. The OLED of claim 1 , wherein the first grating structure has an average amplitude between 30 nm and 150 nm.

13. The OLED of claim 1 , wherein the first interface has an area, wherein the first grating structure covers at least 70% of the area of the first interface.

14. The OLED of claim 1 , wherein a second interface between the light extraction layer and the substrate comprises a second grating structure.

15. The OLED of claim 14 , wherein the second grating structure has an average periodicity between 200 nm and 2 μm.

16. The OLED of claim 14 , wherein the second grating structure has an average amplitude between 30 nm and 150 nm.

17. The OLED of claim 14 , wherein the second interface has an area, wherein the second grating structure covers at least 70% of the area of the second interface.

18. The OLED of claim 1 , wherein the light extraction layer has a thickness between 50 nm and 150 nm.

19. The OLED of claim 1 , wherein the light-emitting layer generates light having a peak wavelength between 400 nm and 700 nm.

20. The OLED of claim 1 , wherein the light-emitting layer comprises Alq 3 , Ir(ppy) 3 , Flrpic, mCP, MEH-PPV, mCP:Ir(piq) 3 , mCP:Ir(ppy) 3 , mCP:Flrpic, Ir(ppy) 3 :CBP and/or Ir(ppy) 3 :TCTA.

21. The OLED of claim 1 , wherein the substrate has a refractive index of at least 1.50.

22. The OLED of claim 1 , wherein the substrate has a refractive index between 1.50 and 1.80.

23. The OLED of claim 1 , wherein the substrate comprises glass and/or sapphire.

24. The OLED of claim 1 , wherein the substrate is at least partially transparent to a peak wavelength of light generated by the light-emitting layer.

25. The OLED of claim 1 , wherein an external surface of the substrate comprises a third grating structure.

26. The OLED of claim 1 , wherein the third grating structure has an average periodicity between 200 nm and 2 μm.

27. The OLED of claim 1 , wherein the third grating structure has an average amplitude between 30 nm and 150 nm.

28. The OLED of claim 1 , wherein the external surface of the substrate has an area, wherein the third grating structure covers at least 70% of the area of the external surface of the substrate.

29. The OLED of claim 1 , wherein at least a portion of the external surface of the substrate is substantially rough.

30. The OLED of claim 1 , wherein at least a portion of the external surface of the substrate has a root mean square surface roughness of at least 100 nm.

31. The OLED of claim 1 , wherein the first electrode is an anode and the second electrode is a cathode.

32. The OLED of claim 1 , wherein the refractive index of the first electrode is at least 1.80.

33. The OLED of claim 1 , wherein the refractive index of the first electrode is between 1.80 and 2.00.

34. The OLED of claim 1 , wherein the first electrode is at least partially transparent to a peak wavelength of light generated by the light-emitting layer.

35. The OLED of claim 1 , wherein the first electrode comprises indium tin oxide (ITO).

36. The OLED of claim 1 , wherein a third interface between the first electrode and the one or more organic layers comprises a fourth grating structure.

37. The OLED of claim 36 , wherein the fourth grating structure has an average periodicity between 200 nm and 2 μm.

38. The OLED of claim 36 , wherein the fourth grating structure has an average amplitude between 30 nm and 150 nm.

39. The OLED of claim 36 , wherein the third interface has an area, wherein the fourth grating structure covers at least 70% of the area of the third interface.

40. The OLED of claim 36 , wherein a fourth interface between the one or more organic layers and the second electrode comprises a fifth grating structure.

41. The OLED of claim 40 , wherein fifth grating structure has an average periodicity between 200 nm and 2 μm.

42. The OLED of claim 40 , wherein the fifth grating structure has an average amplitude between 30 nm and 150 nm.

43. The OLED of claim 40 , wherein the fourth interface has an area, wherein the fifth grating structure covers at least 70% of the area of the fourth interface.

44. The OLED of claim 1 , wherein the one or more organic layers have an average refractive index between 1.5 and 1.8.

45. The OLED of claim 1 , wherein each of the one or more organic layers has a refractive index between 1.5 and 1.8.

46. The OLED of claim 1 , wherein the one or more organic layers further comprise a hole transport layer, a hole injection layer, an electron transport layer, and/or an electron injection layer.

47. The OLED of claim 1 , further comprising a microlens array, a macro lens, or a light extraction film positioned adjacent an external surface of the substrate.

48. The OLED of claim 1 , further comprising a resin layer positioned between the substrate and the light extraction layer.

49. The OLED of claim 48 , wherein the resin layer has a refractive index, wherein a difference between the refractive index of the resin layer and a refractive index of the substrate has a magnitude less than 0.1.

50. The OLED of claim 1 , wherein the OLED has a current efficiency of at least 100 cd/A.

51. The OLED of claim 1 , wherein the OLED has a current efficiency of at least 200 cd/A.

52. The OLED of claim 1 , wherein the OLED has a current efficiency in a range between 100 cd/A and 250 cd/A.

53. The OLED of claim 1 , wherein the OLED has an external quantum efficiency (EQE) of at least 40%.

54. The OLED of claim 1 , wherein the OLED has an external quantum efficiency (EQE) of at least 60%.

55. The OLED of claim 1 , wherein the OLED has an external quantum efficiency (EQE) between 40% and 90%.

56. An organic light-emitting diode (OLED), comprising:

a substrate disposed at a bottom of the OLED;

a first electrode supported upon the substrate;

a second electrode;

a plurality of organic layers disposed between the first electrode and the second electrode, wherein plurality of organic layers comprise a light-emitting layer; and

a light extraction layer comprising one or more inorganic materials and positioned between the substrate and the first electrode, wherein a first interface of the light extraction layer and the first electrode comprises a first grating structure, wherein a second interface of the light extraction layer and the substrate comprises a second grating structure, wherein a refractive index of the light extraction layer is 1.45 or less and a refractive index of the first electrode is 1.70 or greater, wherein the OLED is a bottom-emitting OLED, and wherein the substrate is substantially transparent to light emitted from the light-emitting layer.

57. The OLED of claim 56 , wherein a difference between the refractive index of the light extraction layer and the refractive index of the first electrode has a magnitude of at least 0.30.

58. The OLED of claim 56 , wherein a difference between the refractive index of the light extraction layer and the refractive index of the first electrode has a magnitude between 0.20 and 1.00.

59. The OLED of claim 56 , wherein the refractive index of the light extraction layer is 1.40 or less.

60. The OLED of claim 56 , wherein the refractive index of the light extraction layer is between 1.00 and 1.45.

61. The OLED of claim 56 , wherein a difference between the refractive index of the light extraction layer and a refractive index of the substrate has a magnitude of at least 0.05.

62. The OLED of claim 56 , wherein a difference between the refractive index of the light extraction layer and a refractive index of the substrate has a magnitude between 0.05 and 1.00.

63. The OLED of claim 56 , wherein the one or more inorganic materials comprise LiF, KF, and/or AlF 3 .

64. The OLED of claim 56 , wherein the light extraction layer comprises an aerogel.

65. The OLED of claim 56 , wherein the first grating structure has an average periodicity between 200 nm and 2 μm.

66. The OLED of claim 56 , wherein the first grating structure has an average amplitude between 30 nm and 150 nm.

67. The OLED of claim 56 , wherein the first interface has an area, wherein the first grating structure covers at least 70% of the area of the first interface.

68. The OLED of claim 56 , wherein the second grating structure has an average periodicity between 200 nm and 2 μm.

69. The OLED of claim 56 , wherein the second grating structure has an average amplitude between 30 nm and 150 nm.

70. The OLED of claim 56 , wherein the second interface has an area, wherein the second grating structure covers at least 70% of the area of the second interface.

71. The OLED of claim 56 , wherein the light extraction layer has a thickness between 50 nm and 150 nm.

72. The OLED of claim 56 , wherein the light-emitting layer generates light having a peak wavelength between 400 nm and 700 nm.

73. The OLED of claim 56 , wherein the light-emitting layer comprises Alq 3 , Ir(ppy) 3 , FIrpic, mCP, MEH-PPV, mCP:Ir(piq) 3 , mCP:Ir(ppy) 3 , mCP:FIrpic, Ir(ppy) 3 :CBP and/or Ir(ppy) 3 :TCTA.

74. The OLED of claim 56 , wherein the substrate has a refractive index of at least 1.50.

75. The OLED of claim 56 , wherein the substrate has a refractive index between 1.50 and 1.80.

76. The OLED of claim 56 , wherein the substrate comprises at least one of glass and sapphire.

77. The OLED of claim 56 , wherein the substrate is at least partially transparent to a peak wavelength of light generated by the light-emitting layer.

78. The OLED of claim 56 , wherein an external surface of the substrate comprises a third grating structure having an average periodicity between 200 nm and 2 μm and an average amplitude between 30 nm and 150 nm.