Stratified quantum dot phosphor structure

• US 10,319,878 B2
• Filed: 12/21/2017
• Issued: 06/11/2019
• Est. Priority Date: 10/31/2014
• Status: Active Grant

• Current Assignee: Elux Inc.
• Original Assignee: Elux Inc.
• Inventors: Ulmer, Kurt, Koposov, Alexey
• Primary Examiner(s): Yechuri, Sitaramarao S
• Application Number:
  US15/849,859
• Publication Number:
  US 20180138359A1
• Time in Patent Office: 537 Days
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 33/005 Processes
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials

Abstract

A method is presented for fabricating a light emitting diode (LED) device with a stratified quantum dot (QD) structure. The method provides an LED and a stratified QD structure is formed as follows. A first liquid precursor is deposited overlying the LED emission surface to form a transparent first barrier layer. A second liquid precursor is deposited overlying the first barrier layer to form a first layer of discrete QDs. A third liquid precursor is deposited overlying the first layer of QDs to form a transparent second barrier layer. Subsequent to each barrier layer liquid precursor deposition, an annealing is performed to cure the deposited precursor. The first and second barrier layers act to encapsulate the first layer of QDs. The LED emits a first wavelength of light, and the first layer of QDs converts the first wavelength of light to a first color of light in the visible spectrum.

Claims

1. A light emitting diode (LED) display comprising:

a substrate with a plurality of wells formed in a top surface of the substrate;

a plurality of LEDs, each LED occupying a corresponding well and having an exposed light emission surface, with a post extending from the light emission surface;

a plurality of stratified quantum dot (QD) structures, each stratified QD structure overlying a corresponding LED and comprising;

a transparent first barrier layer overlying the LED emission surface and post;

a first layer of discrete QDs overlying the first barrier layer; and

,

a transparent second barrier layer overlying the first layer of QDs.

2. The display of claim 1 wherein the first and second barrier layers encapsulate the first layer of QDs.

3. The display of claim 1 wherein the first and second barrier layers are a material selected from the group consisting of epoxy, methacrylate, silicon polymer, and alternative polymer materials having an index of refraction greater than or equal to 1.4.

4. The display of claim 1 wherein the LED emission surface emits a first wavelength of light;

and,

wherein a second plurality of the stratified QD structures include a first layer of QDs emitting a first color of light in the visible spectrum, different than the first wavelength of light, in response to converting the first wavelength of light.

5. The display of claim 4 wherein each stratified QD structure further comprises:

a second layer of discrete QDs overlying the second barrier layer; and

,

a transparent third barrier layer overlying the second layer of QDs.

6. The display of claim 5 wherein the second layer of QDs emits a second color of light in the visible spectrum, different than the first color and the first wavelength of light, in response to converting the first wavelength of light.

7. The display of claim 1 wherein a first plurality of the LED emission surfaces emits a first wavelength of light;

wherein a second plurality of the stratified QD structures include a first layer of QDs emitting a first color of light in the visible spectrum, different than the first wavelength of light, in response to converting the first wavelength of light; and

,

wherein a second plurality of the stratified QD structures include a first layer of QDs emitting a second color of light in the visible spectrum, different than the first color and the first wavelength of light, in response to converting the first wavelength of light.

8. A method for fabricating a light emitting diode (LED) device with a stratified quantum dot (QD) structure, the method comprising:

providing a substrate with a plurality of wells formed in a top surface of the substrate;

providing a plurality of LEDs, each LED having a light emission surface and a post extending from the light emission surface, and each LED occupying a corresponding well with the light emission surface and post exposed;

forming a plurality of stratified QD structures, with each stratified QD structure overlying a corresponding LED, as follows;

depositing a first liquid precursor overlying the LED emission surface and post to form a transparent first barrier layer;

depositing a second liquid precursor overlying the first barrier layer to form a first layer of discrete QDs; and

,

depositing a third liquid precursor overlying the first layer of QDs to form a transparent second barrier layer.

9. The method of claim 8 further comprising:

subsequent to each barrier layer liquid precursor deposition, annealing to cure the deposited precursor; and

,

subsequent to the QD layer liquid precursor deposition, drying to remove solvent from the liquid precursor.

10. The method of claim 8 wherein the first and second barrier layers encapsulate the first layer of QDs.

11. The method of claim 8 wherein the first and second barrier layers are selected from the group consisting of epoxy, methacrylate, silicon polymer, and alternative polymer materials having an index of refraction greater than or equal to 1.4.

12. The method of claim 8 wherein the LED emission surface emits a first wavelength of light;

and,

wherein the first layer of QDs emits a first color of light in the visible spectrum, different than the first wavelength of light, in response to converting the first wavelength of light.

13. The method of claim 12 wherein forming the stratified QD structure further comprises:

depositing a fourth liquid precursor overlying the second barrier level to form a second layer of discrete QDs; and

,

depositing a fifth liquid precursor overlying the second layer of QDs to form a transparent third barrier layer.

14. The method of claim 13 wherein the second layer of QDs emits a second color of light in the visible spectrum, different than the first color and the first wavelength of light, in response to converting the first wavelength of light.

15. The method of claim 8 wherein depositing the first liquid precursor in the corresponding well includes filling any space existing between the LED and a well sidewall with first liquid precursor.

16. The method of claim 8 wherein providing the plurality of LEDs includes providing a first plurality of LEDs, each LED emission surface emitting a first wavelength of light;

wherein forming the plurality of stratified QD structures includes;

forming a second plurality of the stratified QD structures including a first layer of QDs emitting a first color of light in the visible spectrum, different than the first wavelength of light, in response to converting the first wavelength of light; and

,

forming a second plurality of the stratified QD structures including a first layer of QDs emitting a second color of light in the visible spectrum, different than the first color and the first wavelength of light, in response to receiving the first wavelength of light.

17. The method of claim 8 wherein providing the plurality of LEDs includes each LED emission surface emitting a first wavelength of light;

wherein forming the plurality of stratified QD structures includes;

depositing a fourth liquid precursor overlying the second barrier level to form a second layer of discrete QDs; and

,

depositing a fifth liquid precursor overlying the second layer of QDs to form a transparent third barrier layer;

wherein the first layer of QDs emits a first color of light in the visible spectrum, different than the first wavelength of light, in response to converting the first wavelength of light; and

,

wherein second layer of QDs emits a second color of light in the visible spectrum, different than the first color and the first wavelength of light, in response to converting the first wavelength of light.