Color-converting structures and light-emitting structures and visual displays made therewith
Color-conversion structures for converting input pump light of a color to one or more differing colors. In some embodiments, the color-conversion structure includes a color-conversion (CC) layer having an input-side coating configured to optimize the amount of the pump light reaching the CC layer and to optimize the amount of color-converted light output by the CC layer. In some embodiments, the CC layer has an output-side coating configured to minimize the amount of unconverted pump light output from the CC layer and to maximize the color-converted light output from the CC layer. Various treatment for enhancing the performance of color-converting structures are also disclosed, as are a number of material combinations for quantum-well (QW) based CC layers and alternatives to QW-based CC layers. Also disclosed are light-emitting structures that each include a color-conversion structure made in accordance with the present disclosure, as well as displays composed of such light-emitting structures.
1. A color-converting structure for use with a micro-light-emitting-diode (LED) array comprising individually addressable pixel elements each having a size of 30 microns or less and each emitting pump light of a first color composition, the color-converting structure comprising:
a color converting layer having a input side and a output side spaced from the input side, wherein:
the input side is designed and configured to face a light emitting region of the micro-LED array and extend over a plurality of the individually addressable pixel elements;
the color converting layer comprises:
one or more first direct bandgap semiconductor quantum wells, wherein the one or more first direct bandgap semiconductor quantum wells are designed and configured so that, when the color-converting structure is deployed for use with the micro-LED array, the color-converting layer receives the pump light through the input side and the one or more first direct bandgap semiconductor quantum wells convert at least a portion of the pump light from the first color composition to a second color composition different from the first color composition so that the color converting layer outputs color-converted light of the second color composition through the output side; and
the color converting layer further comprises one or more second direct bandgap semiconductor quantum wells formed on the substrate, wherein the one or more second direct bandgap semiconductor quantum wells are designed and configured so that when the color-converting structure is deployed for use with the micro-LED array, the color-converting layer receives the pump light through the input side and the one or more second direct bandgap semiconductor quantum wells convert at least a portion of the pump light from the first color composition to a third color composition different from each of the first and second color compositions so that the color converting layer further outputs color-converted light of the third color composition through the output side.
2. The color-converting structure according to claim 1 , wherein the one or more first direct bandgap semiconductor quantum wells are not present within the color converting layer where the one or more second direct bandgap semiconductor quantum wells are present and the one or more second direct bandgap semiconductor quantum wells are not present within the color converting layer where the one or more first direct bandgap semiconductor quantum wells are present.
3. The color converting structure according to claim 2 , wherein the color converting layer includes regions where neither the one or more first direct bandgap semiconductor quantum wells nor the one or more second direct bandgap semiconductor quantum wells are present so that a portion of the pump light can pass through the color converting structure without color conversion.
4. The color converting structure according to claim 3 , wherein the first color composition is blue, the second color composition is green, and the third color composition is red.
5. The color converting structure according to claim 1 , wherein:
the one or more second direct bandgap semiconductor quantum wells have a higher bandgap than the one or more first direct bandgap semiconductor quantum wells;
the one or more second direct bandgap semiconductor quantum wells are located closer to the output side of the color converting layer than the one or more first direct bandgap semiconductor quantum wells; and
the one or more second direct bandgap semiconductor quantum wells are present where than the one or more first direct bandgap semiconductor quantum wells are present.
6. The color converting structure according to claim 5 , wherein the second color composition is green and the third color composition is red.
7. A color-converting structure for use with a micro-light-emitting-diode (LED) array comprising individually addressable pixel elements each having a size of 30 microns or less and each emitting pump light of a first color composition, the color-converting structure comprising:
a color converting layer having a input side and a output side spaced from the input side, wherein:
the input side is designed and configured to face a light emitting region of the micro-LED array and extend over a plurality of the individually addressable pixel elements;
the color converting layer comprises:
one or more first direct bandgap semiconductor quantum wells, wherein the one or more first direct bandgap semiconductor quantum wells are designed and configured so that, when the color-converting structure is deployed for use with the micro-LED array, the color-converting layer receives the pump light through the input side and the one or more first direct bandgap semiconductor quantum wells convert at least a portion of the pump light from the first color composition to a second color composition different from the first color composition so that the color converting layer outputs color-converted light of the second color composition through the output side; and
the color converting layer further comprises a quantum well structure formed separately from the one or more first direct bandgap semiconductor quantum wells and secured to the one or more first direct bandgap semiconductor quantum wells via a bonding agent, wherein the quantum well structure comprises one or more second direct bandgap semiconductor quantum wells are designed and configured so that when the color-converting structure is deployed for use with the micro-LED array, the color-converting layer receives the pump light through the input side and the one or more second direct bandgap semiconductor quantum wells convert at least a portion of the pump light from the first color composition to a third color composition different from each of the first and second color compositions so that the color converting layer further outputs color-converted light of the third color composition through the output side.
8. The color-converting structure according to claim 7 , wherein the one or more first direct bandgap semiconductor quantum wells are not present within the color converting layer where the one or more second direct bandgap semiconductor quantum wells are present and the one or more second direct bandgap semiconductor quantum wells are not present within the color converting layer where the one or more first direct bandgap semiconductor quantum wells are present.
9. The color converting structure according to claim 8 , wherein the color converting layer includes regions where neither the one or more first direct bandgap semiconductor quantum wells nor the one or more second direct bandgap semiconductor quantum wells are present so that a portion of the pump light can pass through the color converting structure without color conversion.
10. The color converting structure according to claim 9 , wherein the first color composition is blue, the second color composition is green, and the third color composition is red.
11. The color converting structure according to claim 7 , wherein:
the one or more second direct bandgap semiconductor quantum wells have a higher bandgap than the one or more first direct bandgap semiconductor quantum wells;
the one or more second direct bandgap semiconductor quantum wells are located closer to the output side of the color converting layer than the one or more first direct bandgap semiconductor quantum wells; and
the one or more second direct bandgap semiconductor quantum wells are present where than the one or more first direct bandgap semiconductor quantum wells are present.
12. The color converting structure according to claim 11 , wherein the second color composition is green and the third color composition is red.