Stabilized quantum dot structure and method of making a stabilized quantum dot structure

• US 9,780,266 B2
• Filed: 06/29/2016
• Issued: 10/03/2017
• Est. Priority Date: 06/30/2015
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Lotito, Kenneth, Gresback, Ryan, Fini, Paul, Ibbetson, James, Keller, Bernd
• Primary Examiner(s): AU, BAC H
• Application Number:
  US15/196,906
• Publication Number:
  US 20170005241A1
• Time in Patent Office: 461 Days
• CPC Class Codes: B82B 1/00 Nanostructures formed by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
• CPC Class Codes: B82B 3/00 Manufacture or treatment of nanostructures by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
• CPC Class Codes: C09K 11/02 Use of particular materials as binders, particle coatings or suspension media therefor
• CPC Class Codes: C09K 11/565 with zinc cadmium
• CPC Class Codes: C09K 11/883 with zinc or cadmium
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/483 Containers
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/52 Encapsulations
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

A stabilized quantum dot structure for use in a light emitting diode (LED) comprises, according to one embodiment, a luminescent particle comprising one or more semiconductors, a buffer layer overlying the luminescent particle, where the buffer layer comprises an amorphous material, and a barrier layer overlying the buffer layer, where the barrier layer comprises oxygen, nitrogen and/or carbon. According to another embodiment, the stabilized quantum dot structure includes a luminescent particle comprising one or more semiconductors, and a treated buffer layer comprising amorphous silica overlying the luminescent particle, where the stabilized quantum dot structure exhibits a quantum yield of at least about 0.7 when exposed to a blue light flux of about 30 W/cm² at a temperature of 80-85° C. and relative humidity of 5% for 500 hours.

Claims

1. A stabilized quantum dot structure for use in a light emitting device, the stabilized quantum dot structure comprising:

a luminescent particle comprising one or more semiconductors;

a buffer layer overlying the luminescent particle, the buffer layer comprising an amorphous material; and

a barrier layer overlying the buffer layer, the barrier layer comprising oxygen, nitrogen and/or carbon.

2. The stabilized quantum dot structure of claim 1, wherein the amorphous material is selected from the group consisting of amorphous silica, amorphous titania, amorphous carbon, amorphous alumina, amorphous silicon oxycarbide, or an amorphous aluminosilicate.

3. The stabilized quantum dot structure of claim 1, wherein the barrier layer comprises an oxide, a carbide, a nitride, an oxynitride or an oxycarbide.

4. The stabilized quantum dot structure of claim 3, wherein the barrier layer comprises an insulating oxide selected from the group consisting of:

aluminum oxide, zirconium oxide and hafnium oxide.

5. The stabilized quantum dot structure of claim 3, wherein the barrier layer comprises a semiconducting oxide selected from the group consisting of:

zinc oxide, titanium dioxide, indium oxide, tin oxide, nickel oxide and copper oxide;

or a conducting oxide selected from the group consisting of;

indium-tin oxide, aluminum-doped zinc oxide, and gallium-doped zinc oxide.

6. The stabilized quantum dot structure of claim 3, wherein the barrier layer comprises:

a nitride selected from the group consisting of silicon nitride, aluminum nitride, boron nitride, and gallium nitride;

or a carbide selected from the group consisting of;

silicon carbide and boron carbide.

7. The stabilized quantum dot structure of claim 1, wherein one or both of the buffer layer and the barrier layer are substantially transparent to visible light.

8. The stabilized quantum dot structure of claim 1, wherein the buffer layer further comprises an ionic species selected from the group consisting of K and Na, the buffer layer being a treated buffer layer.

9. The stabilized quantum dot structure of claim 1, wherein the buffer layer is a densified buffer layer comprising amorphous silica, an FTIR spectrum of the stabilized quantum dot structure exhibiting a peak intensity ratio R=I₁₀₅₀/I₃₃₀₀ of at least about 35, where I₁₀₅₀ is a peak intensity at about 1050 cm⁻

1 and I₃₃₀₀ is a peak intensity at about 3300 cm<sup>−

1</sup>.

10. The stabilized quantum dot structure of claim 1, wherein the luminescent particle comprises a core-shell structure including a semiconducting core and one or more semiconducting shells overlying the semiconducting core.

11. The stabilized quantum dot structure of claim 1, wherein each of the buffer layer and the barrier layer has a thickness of from about 2 nm to about 50 nm.

12. The stabilized quantum dot structure of claim 1, wherein the luminescent particle has a size of about 100 nm or less.

13. The stabilized quantum dot structure of claim 1 exhibiting a quantum yield of at least about 0.7 when exposed to a blue light flux of 30 W/cm² at a temperature of 80-85°

C. and relative humidity of 5% for 500 hours.

14. A light emitting device comprising a blue light emitting diode (LED) chip having a dominant wavelength of 425 nm to 475 nm in optical communication with a plurality of the stabilized quantum dot structures of claim 1 for down conversion of light emitted from the blue LED chip.