Light extraction through adhesive layer between LED and converter
An adhesive layer is disclosed and may include a plurality of short chain molecules, each of the plurality of the short chain molecules including a first end and a second end such that the distance between the first end and second end is less than 100 nm and such that first end is configured to attach to a first surface and the second end is configured to attach to a second surface.
1. A light emitting device comprising:
a semiconductor light emitting diode structure;
a substrate transparent to light emitted by the semiconductor light emitting diode structure and comprising a flat top surface, an oppositely positioned bottom surface, and side surfaces connecting the top and bottom surfaces, the bottom surface disposed on or adjacent the semiconductor light emitting diode structure;
a ceramic phosphor wavelength converting structure comprising a flat surface disposed adjacent the flat top surface of the substrate; and
an adhesive layer disposed between and bonding the substrate and the ceramic phosphor wavelength converting structure to each other, the adhesive layer comprising:
a plurality of short chain molecules each having a chain length of less than or equal to 100 nanometers, a first end attached to the flat surface of the ceramic phosphor wavelength converting structure, and a second end attached to the top flat surface of substrate; or
a nanostructured layer imposing a local phase gradient that increases a critical angle for total internal reflection for light emitted into the substrate from the semiconductor light emitting diode structure and incident on the adhesive layer from the substrate; or
a plurality of short chain molecules each having a chain length of less than or equal to 100 nanometers, a first end attached to the flat surface of the ceramic phosphor wavelength converting structure, and a second end attached to the top flat surface of substrate, and a nanostructured layer imposing a local phase gradient that increases a critical angle for total internal reflection for light emitted into the substrate from the semiconductor light emitting diode structure and incident on the adhesive layer.
2. The light emitting device of claim 1 , wherein the adhesive layer comprises a plurality of short chain molecules each having a chain length of less than or equal to 100 nanometers, a first end attached to the flat surface of the ceramic phosphor wavelength converting structure, and a second end attached to the top flat surface of substrate.
3. The light emitting device of claim 2 , wherein the short chain molecules each have a chain length of less than or equal to 10 nanometers.
4. The light emitting device of claim 2 , comprising an organosilane self-assembled monolayer coating the top surface of the substrate or the flat surface of the ceramic phosphor wavelength converting structure and facilitating attachment of the short chain molecules to the coated surface.
5. The light emitting device of claim 1 , wherein the adhesive layer comprises a nanostructured layer imposing a local phase gradient that increases the critical angle for total internal reflection for light emitted into the substrate from the semiconductor light emitting diode structure and incident on the adhesive layer from the substrate.
6. The light emitting device of claim 5 , wherein the nanostructured layer imposes a local phase gradient that increases to at least 60 degrees the critical angle for total internal reflection for light emitted into the substrate from the semiconductor light emitting diode structure and incident on the adhesive layer from the substrate.
7. The light emitting device of claim 6 , wherein the nanostructured layer imposes a local phase gradient that increases to at least 80 degrees the critical angle for total internal reflection for light emitted into the substrate from the semiconductor light emitting diode structure and incident on the adhesive layer from the substrate.
8. The light emitting device of claim 5 , wherein the nanostructured layer is or comprises a metasurface or a metamaterial.
9. The light emitting device of claim 8 , wherein the metasurface or metamaterial comprises a plurality of nanoantennas.
10. The light emitting device of claim 9 , wherein the plurality of nanoantennas are arranged in a lattice.
11. The light emitting device of claim 9 , wherein each nanoantenna has a largest dimension less than or equal to a wavelength of light emitted by the semiconductor light emitting diode structure.
12. The light emitting device of claim 1 , wherein the adhesive layer comprises a plurality of short chain molecules each having a chain length of less than or equal to 100 nanometers, a first end attached to the flat surface of the ceramic phosphor wavelength converting structure, and a second end attached to the top flat surface of substrate, and a nanostructured layer imposing a local phase gradient that increases the critical angle for total internal reflection for light emitted into the substrate from the semiconductor light emitting diode structure and incident on the adhesive layer.
13. The light emitting device of claim 12 , comprising an organosilane self-assembled monolayer coating the top surface of the substrate or the flat surface of the ceramic phosphor wavelength converting structure and facilitating attachment of the short chain molecules to the coated surface.
14. The light emitting device of claim 12 , wherein the nanostructured layer imposes a local phase gradient that increases to at least 60 degrees the critical angle for total internal reflection for light emitted into the substrate from the semiconductor light emitting diode structure and incident on the adhesive layer from the substrate.
15. The light emitting device of claim 14 , wherein the nanostructured layer imposes a local phase gradient that increases to at least 80 degrees the critical angle for total internal reflection for light emitted into the substrate from the semiconductor light emitting diode structure and incident on the adhesive layer from the substrate.
16. The light emitting device of claim 12 , wherein the nanostructured layer is or comprises a metasurface or a metamaterial.
17. The light emitting device of claim 16 , wherein the metasurface or metamaterial comprises a plurality of nanoantennas.
18. The light emitting device of claim 17 , wherein the plurality of nanoantennas are arranged in a lattice.
19. The light emitting device of claim 18 , wherein each nanoantenna has a largest dimension less than or equal to a wavelength of light emitted by the semiconductor light emitting diode structure.