Advanced light extraction structure

1. A light emitting diode (LED) display comprising, in order:

a planarization layer,

an array of lenses, and

an array of light emitting pixels, wherein

the array of lenses comprise a nanocomposite having a refractive index in the range of greater than 1.7 to 1.9 at 400 nm, the nanocomposite comprising inorganic nanocrystals and a polymeric matrix, wherein the refractive index of the nanocrystals is greater than the refractive index of the polymeric matrix; and wherein

the planarization layer has a refractive index that is less than the refractive index of the nanocomposite.

2. The LED display of claim 1 , further comprising an encapsulation or a substrate layer in contact with the planarization layer on a surface of the planarization layer opposite a surface facing the array of light emitting pixels.

3. The LED display of claim 1 , wherein the nanocomposite is UV curable.

4. The LED display of claim 1 , wherein the nanocomposite is thermally curable.

5. The LED display of claim 1 , wherein the nanocomposite comprises ZrO 2 , TiO 2 , ZnO, MgO, HfO 2 , Nb 2 O 5 , Ta 2 O 5 , or Y 2 O 3 nanocrystals.

6. The LED display of claim 5 , wherein the nanocrystals have a size of less than 10 nm in at least one dimension.

7. The LED display of claim 5 , wherein the nanocomposite comprises a polymer, and wherein the polymer optionally comprises an acrylic, an epoxy or a silicone.

8. The LED display of claim 7 , wherein the polymer comprises a siloxane, a polycarbonate, a polyurethane, a polyimide, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(styrene sulfonate) (PSS), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or poly(4,4-dioctylcyclopentadithiophene).

9. The LED display of claim 1 , wherein at least one of the lenses covers a single pixel.

10. The LED display of claim 1 , wherein at least one of the lenses covers multiple pixels.

11. The LED display of claim 1 , wherein a lens of the array of lenses comprises a spherical surface, a semi-spherical surface, a hyper-hemispherical surface or a parabolic surface.

12. The LED display of claim 1 , wherein a lens of the array of lenses comprises a concave surface, a convex surface, a sub-wavelength pyramid array surface or a textured surface.

13. The LED display of claim 1 , wherein a lens of the array of lenses comprises a graded or gradient index profile along at least one dimension of the lens.

14. The LED display of claim 1 , wherein the array of lenses is separated from the array of light emitting pixels by a distance of less than the wavelength of the highest energy photons emitted by the array of pixels.

15. The LED display of claim 1 , wherein the nanocrystals are at least partially capped.

16. A light emitting diode (LED) display comprising, in order:

an array of lenses, and

an array of light emitting pixels, wherein

the array of lenses comprises a nanocomposite, wherein the nanocomposite comprises inorganic nanocrystals and a polymeric matrix, the nanocomposite having a refractive index between 1.6 and 1.9 at 400 nm, wherein the refractive index of the nanocrystals is greater than the refractive index of the polymeric matrix; and wherein

the array of lenses is not in contact with a planarization layer and/or a substrate layer spaced further away from the pixel than the array of lenses.

17. The LED display of claim 16 , wherein the nanocomposite is UV curable.

18. The LED display of claim 16 , wherein the nanocomposite is thermally curable.

19. The LED display of claim 16 , wherein the nanocomposite comprises ZrO 2 , TiO 2 , ZnO, MgO, HfO 2 , Nb 2 O 5 , Ta 2 O 5 , or Y 2 O 3 nanocrystals.

20. The LED display of claim 19 , wherein the nanocrystals have a size of less than 10 nm in at least one dimension.

21. The LED display of claim 16 , wherein the nanocomposite comprises a polymer, and wherein the polymer optionally comprises an acrylic, an epoxy or a silicone.

22. The LED display of claim 21 , wherein the polymer comprises a siloxane, a polycarbonate, a polyurethane, a polyimide, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(styrene sulfonate) (PSS), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or poly(4,4-dioctylcyclopentadithiophene).

23. The LED display of claim 16 , wherein at least one of the lenses covers a single pixel.

24. The LED display of claim 16 , wherein at least one of the lenses covers multiple pixels.

25. The LED display of claim 16 , wherein a lens of the array of lenses comprises a spherical surface, a semi-spherical surface, a hyper-hemispherical surface, or a parabolic surface.

26. The LED display of claim 16 , wherein a lens of the array of lenses comprises a concave surface, a convex surface, a sub-wavelength pyramid array surface, or a textured surface.

27. The LED display of claim 16 , wherein a lens of the array of lenses comprises a graded or gradient index profile along at least one dimension of the lens.

28. The LED display of claim 16 , wherein the array of lenses is separated from the array of light emitting pixels by a distance of less than the wavelength of the highest energy photons emitted by the array of pixels.

29. The LED display of claim 16 , wherein the nanocrystals are at least partially capped.

30. A method of making a light emitting diode (LED) display comprising:

(a) forming an array of light-emitting pixels;

(b) providing a planarization layer; and

(c) forming an array of lenses between the light-emitting pixels and the planarization layer, wherein

the array of lenses comprise a nanocomposite having a refractive index in the range of greater than 1.7 to 1.9 at 400 nm, the nanocomposite comprising inorganic nanocrystals and a polymeric matrix, wherein the refractive index of the nanocrystals is greater than the refractive index of the polymeric matrix; and wherein

the planarization layer has a refractive index that is less than the refractive index of the nanocomposite.

31. The method of claim 30 , further comprising forming an encapsulation or substrate layer so as to be in contact with the planarization layer on a surface of the planarization layer opposite a surface facing the array of light emitting pixels.

32. The method of claim 30 , wherein the nanocomposite is UV curable.

33. The method of claim 30 , wherein the nanocomposite is thermally curable.

34. The method of claim 30 , wherein the nanocrystals have a size of less than 10 nm in at least one dimension.

35. The method of claim 30 , wherein the polymeric matrix comprises an acrylic polymer, an epoxy polymer or a silicone polymer.

36. The method of claim 30 , wherein the polymeric matrix comprises a siloxane, a polycarbonate, a polyurethane, a polyimide, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(styrene sulfonate) (PSS), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or poly(4,4-dioctylcyclopentadithiophene).

37. The method of claim 30 , wherein at least one of the lenses covers a single pixel.

38. The method of claim 30 , wherein at least one of the lenses covers multiple pixels.

39. The method of claim 30 , wherein at least one lens of the array of lenses comprises a spherical surface, a semi-spherical surface, a hyper-hemispherical surface or a parabolic surface.

40. The method of claim 30 , wherein at least one lens of the array of lenses comprises a concave surface, a convex surface, a sub-wavelength pyramid array surface or a textured surface.

41. The method of claim 30 , wherein at least one lens of the array of lenses comprises a graded or gradient index profile along at least one dimension of the lens.

42. The method of claim 30 , wherein the array of lenses is separated from the array of light emitting pixels by a distance of less than the wavelength of the highest energy photons emitted by the array of pixels.

43. The method of claim 30 , further comprising forming the planarization layer so as to cover the array of lenses.

44. The method of claim 30 , which comprises applying a prefabricated sheet comprising the array of lenses on top of the array of light-emitting pixels.

45. The method of claim 44 , wherein the applying is practiced by roll-to-roll printing.

46. The method of claim 30 , wherein step (c) is practiced by applying a layer of the nanocomposite over the array of pixels by spin-coating, dip-coating, blade coating, draw-bar coating, slot-die coating or spraying, and thereafter forming the array of lenses by patterning the applied layer of material.

47. The method of claim 46 , wherein the patterning of the applied layer is practiced by imprint lithography, optical lithography.

48. The method of claim 46 , wherein the array of lenses is formed by UV curing the nanocomposite.

49. The method of claim 46 , wherein the array of lenses is formed by thermally curing the nanocomposite.