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 light emitting layer;
a substrate transparent to light emitted by the light emitting layer and comprising a top surface, an oppositely positioned bottom surface, and side surfaces connecting the top and bottom surfaces, the bottom surface disposed on or adjacent the light emitting layer;
a wavelength converting structure comprising a first surface disposed adjacent the top surface of the substrate; and
an adhesive layer disposed between, disposed in direct contact with, and bonding the substrate and the wavelength converting structure to each other, the adhesive layer comprising a nanostructured layer that increases transmission of a light through the adhesive layer, the light emitted into the substrate from the light emitting layer and incident on the adhesive layer from the substrate.
2. The light emitting device of claim 1 , wherein the nanostructured layer increases the critical angle for total internal reflection for the light emitted into the substrate from the light emitting layer and incident on the adhesive layer from the substrate.
3. The light emitting device of claim 2 , wherein the nanostructured layer imposes a local phase gradient that increases the critical angle for total internal reflection for light emitted into the substrate from the light emitting layer and incident on the adhesive layer from the substrate.
4. The light emitting device of claim 3 , 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 light emitting layer and incident on the adhesive layer from the substrate.
5. The light emitting device of claim 4 , 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 light emitting layer and incident on the adhesive layer from the substrate.
6. The light emitting device of claim 1 , wherein the nanostructured layer is or comprises at least one of a metasurface, metamolecules, photonic crystals, and plasmonic nanostructures.
7. The light emitting device of claim 6 , wherein the at least one of a metasurface, metamolecules, photonic crystals, and plasmonic nanostructures comprises nanoantennas.
8. The light emitting device of claim 7 , wherein the nanoantennas are arranged in a lattice.
9. The light emitting device of claim 8 , wherein each nanoantenna has a largest dimension less than or equal to a wavelength of light emitted by the semiconductor diode structure.
10. The light emitting device of claim 1 , wherein the nanostructured layer directly contacts the substrate but does not directly contact the wavelength converting structure.
11. A light emitting device comprising:
a light emitting layer;
a substrate transparent to light emitted by the light emitting layer and comprising a top surface, an oppositely positioned bottom surface, and side surfaces connecting the top and bottom surfaces, the bottom surface disposed on or adjacent the light emitting layer;
a wavelength converting structure comprising a first surface disposed adjacent the top surface of the substrate; and
an adhesive layer disposed between and bonding the substrate and the wavelength converting structure to each other, the adhesive layer comprising short chain molecules each having a first end attached to the first surface of the wavelength converting structure, and a second end attached to the top surface of substrate, and a nanostructured layer that increases transmission of light through the adhesive layer, the light emitted into the substrate from the light emitting layer and incident on the adhesive layer from the substrate.
12. The light emitting device of claim 11 , wherein the adhesive layer has a thickness of less than or equal to 100 nanometers.
13. The light emitting device of claim 12 , wherein each of the short chain molecules has a chain length of less than or equal to 100 nanometers.
14. The light emitting device of claim 11 , wherein the nanostructured layer imposes a local phase gradient that increases a critical angle for total internal reflection for light emitted into the substrate from the light emitting layer and incident on the adhesive layer.
15. A light emitting device comprising:
a light emitting layer;
a substrate transparent to light emitted by the light emitting layer and comprising a top surface, an oppositely positioned bottom surface, and side surfaces connecting the top and bottom surfaces, the bottom surface disposed on or adjacent the light emitting layer;
a wavelength converting structure comprising a first surface disposed adjacent the top surface of the substrate; and
an adhesive layer disposed between and bonding the substrate and the wavelength converting structure to each other, the adhesive layer comprising short chain molecules and having a thickness less than or equal to 100 nanometers.
16. The light emitting device of claim 15 , wherein each of the short chain molecules has a chain length of less than or equal to 100 nanometers.
17. The light emitting device of claim 15 , wherein the short chain molecules each have a chain length of less than or equal to 10 nanometers.
18. The light emitting device of claim 15 , where each short chain molecule has a first end attached to the first surface of the wavelength converting structure, and a second end attached to the top surface of substrate.
19. The light emitting device of claim 15 , wherein each of the short chain molecules comprises a linker molecule at each end of the short chain molecule and comprises a short polymer chain or a short DNA strand.
20. The light emitting device of claim 15 , 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.