Wavelength converting layer patterning for LED arrays
A wavelength converting layer is disclosed that includes a plurality of phosphor grains 50-500 nm in size and encapsulated in cerium free YAG shells and a binder material binding the plurality of phosphor grains, the wavelength converting layer having a thickness of 5-20 microns attached to the light emitting surface.
1. A method comprising:
depositing a wavelength converting layer onto a surface, the wavelength converting layer comprising a photoinitiator and a binder material; and
patterning the wavelength converting layer by applying a nanoimprint lithography process to the wavelength converting layer, the nanoimprint lithography process comprising:
applying a nanoimprint mold on the wavelength converting layer;
curing the wavelength converting layer such that the photoinitiator experiences decarboxylation; and
removing the nanoimprint mold from the wavelength converting layer after the curing.
2. The method of claim 1 , wherein patterning of the wavelength converting layer defines an array of wavelength converting pixels.
3. The method of claim 2 , wherein the pixels in the array have widths of 100 microns or less, spacings between adjacent pixels of 20 microns or less, or widths of 100 microns or less and spacings between adjacent pixels of 20 microns or less.
4. The method of claim 3 , comprising aligning an array of light emitting semiconductor diodes with the array of wavelength converting pixels and attaching each wavelength converting pixel to a corresponding light emitting semiconductor diode.
5. The method of claim 1 , wherein the binder material comprises one or more of a siloxane material, a polysilazane, or a sol-gel material.
6. The method of claim 1 , wherein the photoinitiator is a salt.
7. The method of claim 1 , wherein curing the wavelength converting layer comprises illuminating the wavelength layer with ultraviolet light absorbed by the photoinitiator to cause the decarboxylation.
8. The method of claim 7 , comprising illuminating the wavelength converting layer with ultraviolet light transmitted through the nanoimprint mold.
9. The method of claim 1 , wherein the decarboxylated photoinitator catalyzes reaction of reactive chain ends or crosslinkable substrates of the binder material.
10. The method of claim 1 , wherein the decarboxylated photoinitiator catalyzes a condensation polymerization or a ring opening polymerization of the binder material.
11. The method of claim 1 , wherein the decarboxylation produces a super base.
12. The method of claim 11 , comprising removing the super base by evaporation or thermal decomposition of the super base after curing of the binder.
13. The method of claim 1 , wherein:
the binder material comprises one or more of a siloxane material, a polysilazane, or a sol-gel material;
the photoinitiator is a salt;
curing the wavelength converting layer comprises illuminating the wavelength converting layer with ultraviolet light absorbed by the photoinitiator to cause the decarboxylation of the photoinitiator; and
decarboxylation of the photoiniator produces a super base.
14. The method of claim 13 , wherein the super base catalyzes reaction of chain ends or crosslinkable substrates of the binder material.
15. The method of claim 13 , wherein the super base catalyzes a condensation polymerization or a ring opening polymerization of the binder material.
16. The method of claim 13 , comprising removing the super base by evaporation or thermal decomposition of the super base after curing of the binder.
17. The method of any of claim 13 , wherein patterning of the wavelength converting layer defines an array of wavelength converting pixels.
18. The method of claim 17 , wherein the pixels in the array have widths of 100 microns or less, spacings between adjacent pixels of 20 microns or less, or widths of 100 microns or less and spacings between adjacent pixels of 20 microns or less.
19. The method of claim 17 , comprising aligning an array of light emitting semiconductor diodes with the array of wavelength converting pixels and attaching each wavelength converting pixel to a corresponding light emitting semiconductor diode.
20. The method of claim 19 , wherein the pixels in the array have widths of 100 microns or less, spacings between adjacent pixels of 20 microns or less, or widths of 100 microns or less and spacings between adjacent pixels of 20 microns or less.