Advanced light extraction structure
Light-emitting devices and methods of making the same are described whereby lenses of any array include a material with a higher refractive index than an encapsulation layer of a substrate layer, the refractive index of the material being in a range of greater than 1.7 to 1.9 at 400 nm. The material forming the lenses includes nanocomposite comprised of inorganic nanocrystals and a polymeric matrix, wherein the nanocrystals are selected from the group consisting of ZrO 2 , ZnO, MgO, HfO 2 , NbO 5 , Ta 2 O 5 and Y 2 O 3 . A 3-4 micron thick sample of the nanocomposite has an optical transmittance of at least 80% over a range of 440 nm to 800 nm.
1. A light emitting device comprising, in order:
an encapsulation layer or a substrate layer,
an array of lenses, and
an array of light emitting pixels at least partially covered by the array of lenses, wherein at least one of the lenses covers at least one of the pixels, wherein
the lenses comprise a material with a higher refractive index than the encapsulation layer of the substrate layer, the refractive index of the material being in a range of greater than 1.7 to 1.9 at 400 nm, and wherein
the material comprises a nanocomposite comprised of inorganic nanocrystals and a polymeric matrix, wherein the nanocrystals are selected from the group consisting of ZrO 2 , ZnO, MgO, HfO 2 , NbO 5 , Ta 2 O 5 and Y 2 O 3 , and wherein
a 3-4 micron thick sample of the nanocomposite has an optical transmittance of at least 80% over a range of 440 nm to 800 nm.
2. The device of claim 1 , wherein the encapsulation or the substrate layer is 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 device of claim 1 , wherein the nanocomposite is UV curable.
4. The device of claim 1 , wherein the nanocomposite is thermally curable.
5. The device of claim 1 , wherein the nanocrystals have a size of less than 10 nm in at least one dimension.
6. The device of claim 1 , wherein the polymeric matrix comprises an acrylic polymer, an epoxy polymer or a silicone polymer.
7. The device of claim 1 , 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).
8. The device of claim 1 , wherein at least one of the lenses covers a single pixel.
9. The device of claim 1 , wherein at least one of the lenses covers multiple pixels.
10. The device of claim 1 , 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.
11. The device of claim 1 , 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.
12. The device of claim 1 , 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.
13. The device 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.
14. A method of making a light emitting device comprising:
(a) forming an array of light-emitting pixels;
(b) forming an array of lenses relative to the array of light emitting pixels such that at least one of the lenses in the array of lenses at least partially covers at least one of the light-emitting pixels of the array of light-emitting pixels; and
(c) providing encapsulation layer or a substrate layer so as to cover the array of light-emitting pixels and the array of lenses, wherein
the lenses comprise a material with a higher refractive index than the encapsulation layer or the substrate layer, the refractive index of the material being in a range of greater than 1.7 to 1.9 at 400 nm, and wherein
the material comprises a nanocomposite comprised of inorganic nanocrystals and a polymeric matrix, wherein the nanocrystals are selected from the group consisting of ZrO 2 , ZnO, MgO, HfO 2 , NbO 5 , Ta 2 O 5 and Y 2 O 3 , and wherein
a 3-4 micron thick sample of the nanocomposite has an optical transmittance of at least 80% over a range of 440 nm to 800 nm.
15. The method of claim 14 , wherein the encapsulation or the substrate layer is formed 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.
16. The method of claim 14 , wherein the nanocomposite is UV curable.
17. The method of claim 14 , wherein the nanocomposite is thermally curable.
18. The method of claim 14 , wherein the nanocrystals have a size of less than 10 nm in at least one dimension.
19. The method of claim 14 , wherein the polymeric matrix comprises an acrylic polymer, an epoxy polymer or a silicone polymer.
20. The method of claim 14 , 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).
21. The method of claim 14 , wherein at least one of the lenses covers a single pixel.
22. The method of claim 14 , wherein at least one of the lenses covers multiple pixels.
23. The method of claim 14 , 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.
24. The method of claim 14 , 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.
25. The method of claim 14 , 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.
26. The method of claim 14 , 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.
27. The method of claim 14 , further comprising providing a planarization layer between the array of lenses and the encapsulation layer or substrate layer.
28. The method of claim 14 , wherein steps (a) and (b) are practiced by applying a prefabricated sheet comprising the array of lenses on top of the array of light-emitting pixels.
29. The method of claim 28 , wherein the applying is practiced by roll-to-roll printing.
30. The method of claim 14 , wherein step (b) is practiced by applying a layer of the material with a higher refractive index than the encapsulation layer or the substrate layer over the array of pixels by spin-coating, dip-coating, blade coating, draw-bar coating, slot-die coating or spraying or ink jet printing and thereafter forming the array of lenses by patterning the applied layer of material.
31. The method of claim 30 , wherein the patterning of the applied layer is practiced by imprint lithography or optical lithography.
32. The method of claim 30 , wherein the array of lenses is formed by UV curing the material with a higher refractive index than the encapsulation layer or the substrate layer.
33. The method of claim 30 , wherein the array of lenses is formed by thermally curing the material with a higher refractive index than the encapsulation layer or the substrate layer.