Phosphor with light barriers
A device including a phosphor layer having a plurality of holes or pockets arranged within the phosphor layer to reduce lateral light transmission. The phosphor layer can be sized and positioned to extend over a plurality of LED emitter pixels.
1. A light emitting device comprising:
a set of two or more light emitting diodes (LEDs) forming an array of pixels, each pixel being arranged so as to emit light from a top surface thereof, and being separated from other pixels by one or more interpixel lanes;
a phosphor layer positioned on the top surfaces of two or more pixels of the array so as to span one or more of the interpixel lanes, the phosphor layer including phosphor material and one or more of a ceramic, a glass, or an organic binder; and
a plurality of holes in or through or pockets within the phosphor layer, the holes or pockets forming collectively one or more light barriers within the phosphor layer, one or more of the light barriers being arranged so as to reduce lateral transmission of light through a corresponding region of the phosphor layer spanning a corresponding one of the interpixel lanes, relative to lateral light transmission within regions of the phosphor layer that do not span an interpixel lane.
2. The light emitting device of claim 1 , one or more of the light barriers extending only partly through the phosphor layer.
3. The light emitting device of claim 1 , one or more of the light barriers extending entirely through the phosphor layer.
4. The light emitting device of claim 1 , one or more of the holes or pockets being air-filled.
5. The light emitting device of claim 1 , one or more of the holes or pockets containing metallic or dielectric scattering elements.
6. The light emitting device of claim 1 , one or more of the light barriers being arranged so as to permit only negligible lateral transmission of light through a corresponding region of the phosphor layer spanning a corresponding one of the interpixel lanes.
7. The phosphor structure of claim 1 , the holes or pockets being arranged along the phosphor layer irregularly.
8. The phosphor structure of claim 1 , the holes or pockets being arranged along the phosphor layer in a radial, linear, rectangular, square, or hexagonal pattern.
9. The phosphor structure of claim 1 , the holes or pockets being less than about 400 nm across.
10. The phosphor structure of claim 1 , each hole or pocket being within about 300 nm of another hole or pocket.
11. The light emitting device of claim 1 , each one of the light barriers being positioned over a corresponding interpixel lane.
12. The light emitting device of claim 1 , one or more of the light barriers being positioned over corresponding pixels of the array.
13. The light emitting device of claim 1 , the pixels of the array being less than about 300 microns wide, and the interpixel lanes being less than about 50 microns wide.
14. The light emitting device of claim 1 , the pixels of the array being less than about 100 microns wide, and the interpixel lanes being less than about 20 microns wide.
15. The light emitting device of claim 1 , each of the one or more LEDs including an emitter and distributed Bragg reflectors (DBRs) that are arranged on sidewalls of the emitter and that do not extend into the phosphor layer.
16. A method for making a light emitting device,
the light emitting device comprising:
a set of two or more light emitting diodes (LEDs) forming an array of pixels, each pixel being arranged so as to emit light from a top surface thereof, and being separated from other pixels by one or more interpixel lanes;
a phosphor layer positioned on the top surfaces of two or more pixels of the array so as to span one or more of the interpixel lanes, the phosphor layer including phosphor material and one or more of a ceramic, a glass, or an organic binder; and
a plurality of holes in or through or pockets within the phosphor layer, the holes or pockets forming collectively one or more light barriers within the phosphor layer, one or more of the light barriers being arranged so as to reduce lateral transmission of light through a corresponding region of the phosphor layer spanning a corresponding one of the interpixel lanes, relative to lateral light transmission within regions of the phosphor layer that do not span an interpixel lane,
the method comprising positioning the phosphor layer on the top surfaces of the pixels of the array.
17. The method of claim 16 further comprising, before positioning the phosphor layer on the pixels of the array:
(A) combining ceramic powder precursors, a ceramic binder, phosphor material, and solvent to form a mixture;
(B) coating the mixture of part (A) onto a substrate to form a film, either as (i) a single-layer film or (ii) a multi-layer film comprising multiple slot-die-coated thin films;
(C) creating conditions for forming holes or pockets to form the light barriers within selected regions of the film of part (B) by one or more of (i) deforming or removing material from the film, or (ii) adding to the mixture or to the film one or more of sacrificial material, sintering rods or beads, or polymeric rods or beads; and
(D) after part (C), heating or sintering the film to form the phosphor layer and the plurality of light barriers within the phosphor layer.
18. The method of claim 17 , the holes or pockets being less than about 400 nm across.
19. The method of claim 17 , each hole or pocket being within about 300 nm of another hole or pocket.
20. A method for using a light emitting device,
the light emitting device comprising:
a set of two or more light emitting diodes (LEDs) forming an array of pixels, each pixel being arranged so as to emit light from a top surface thereof, and being separated from other pixels by one or more interpixel lanes;
a phosphor layer positioned on the top surfaces of two or more pixels of the array so as to span one or more of the interpixel lanes, the phosphor layer including phosphor material and one or more of a ceramic, a glass, or an organic binder; and
a plurality of holes in or through or pockets within the phosphor layer, the holes or pockets forming collectively one or more light barriers within the phosphor layer, one or more of the light barriers being arranged so as to reduce lateral transmission of light through a corresponding region of the phosphor layer spanning a corresponding one of the interpixel lanes, relative to lateral light transmission within regions of the phosphor layer that do not span an interpixel lane,
the method comprising causing an electrical current to flow through one or more of the pixels of the array so that light is emitted from those pixels.