Method for fabricating quantum dot light emitting diodes (LEDs) with suppressed photobrighting

• US 10,403,798 B2
• Filed: 05/25/2018
• Issued: 09/03/2019
• Est. Priority Date: 11/20/2017
• Status: Active Grant

• Current Assignee: Elux Inc.
• Original Assignee: Elux Inc.
• Inventors: Koposov, Alexey
• Primary Examiner(s): Kim, Tong-Ho
• Application Number:
  US15/989,431
• Publication Number:
  US 20190157517A1
• Time in Patent Office: 466 Days
• Field of Search: 438 27
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C09K 11/70 containing phosphorus
• CPC Class Codes: C09K 11/7492 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/883 with zinc or cadmium
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/005 relating to encapsulations
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: Y10S 977/774 Exhibiting three-dimensional carrier confinement, e.g. quantum dots
• CPC Class Codes: Y10S 977/813 Of specified inorganic semiconductor composition, e.g. periodic table group IV-VI compositions
• CPC Class Codes: Y10S 977/816 III-N based compounds, e.g. AlxGayInzN
• CPC Class Codes: Y10S 977/818 III-P based compounds, e.g. AlxGayIn2P
• CPC Class Codes: Y10S 977/819 III-As based compounds, e.g. AlxGayInzAs
• CPC Class Codes: Y10S 977/824 Group II-VI nonoxide compounds, e.g. CdxMnyTe
• CPC Class Codes: Y10S 977/892 Liquid phase deposition
• CPC Class Codes: Y10S 977/90 having step or means utilizing mechanical or thermal property, e.g. pressure, heat
• CPC Class Codes: Y10S 977/95 : Electromagnetic energy

Abstract

A device and associated method are provided for a light emitting diode device (LED) with suppressed quantum dot (QD) photobrightening. The QD surfaces, with a maximum cross-sectional dimension of 10 nanometers, are treated with a solution including a multi-valent cation salt. In response to heating the solution, multi-valent cations become attached to the surface of the QD nanocrystals, forming treated QDs that are deposited overlying a top surface of an LED. The LED device emits a non-varying intensity of first wavelength light in the visible spectrum from the treated QDs, when subjected to a continuous exposure of a second wavelength of LED light having an intensity of greater than 50 watts per square centimeter. For example, blue, green, or red color light may be emitted when exposed to LED light in the ultraviolet (UV) spectrum, or a green or red color light when exposed to a blue color LED light.

Claims

1. A method for suppressing quantum dot photobrightening, the method comprising:

providing quantum dots (QD) nanocrystals having a surface with a maximum cross-sectional dimension of 10 nanometers (nm), capable of emissions with the visible spectrum of light;

treating the quantum dot nanocrystal surface with a solution including a multi-valent cation salt;

heating the solution to a temperature in a range of 50 to 200 degrees C.;

in response to heating the solution, attaching elements to the surface of the quantum dot nanocrystals consisting of cations; and

,

forming treated quantum dots with suppressed photobrightening, capable of emitting a non-varying intensity of first wavelength of light in the visible spectrum when subjected to a continuous exposure of a second wavelength of light having an intensity of greater than 50 watts per square centimeter (W/cm²).

2. The method of claim 1 wherein providing the QD nanocrystals includes providing QD nanocrystals with a structure selected from the group consisting of a solitary core and a core-single shell structure.

3. The method of claim 1 wherein providing the QD nanocrystals includes providing QD nanocrystals comprising a binary or binary alloyed material surface;

and,

wherein treating the QD nanocrystals with the solution includes treating the QD nanocrystal surfaces with a solution including a divalent cation salt.

4. The method of claim 3 wherein the QD nanocrystal surface is selected from the group consisting of CdS, CdSe, CdTe, GaAs, InAs, InN, InP, ZnS, ZnSe, ZnTe, and combinations thereof.

5. The method of claim 1 wherein providing the QD nanocrystals includes providing QD nanocrystals with a tertiary or tertiary alloyed material surface;

and,

wherein treating the QD nanocrystals with the solution includes treating the QD nanocrystal surfaces with a solution including a material selected from the group consisting of trivalent cation salts, divalent cation salts, monovalent cation salts, and combinations thereof.

6. The method of claim 5 wherein the QD nanocrystal surface is selected from the group consisting of ZnSSe, ZnSeTe, ZnSTe, CdSSe, CdSeTe, CdSTe, ZnCdS, ZnCdSe, ZnCdTe, ZnCdSSe, ZnCdSeTe, InGaAs, GaAlAs, InGaN, CuInS₂, CuGaS₂, Cu(In,Ga)Se₂, Cu(Zn,Sn)Se₂, Cu(Zn,Sn)S₂, CuIn(Se,S)₂, CuZn(Se,S)₂, CuSn(Se,S)₂, Cu(Zn,Sn)(Se,S)₂, and combinations thereof.

7. The method of claim 1 wherein providing the QD nanocrystals includes providing QD nanocrystals having a Type III-V semiconductor surface;

and,

wherein treating the QD nanocrystals with the solution includes treating the QD nanocrystal surfaces with a solution including a material selected from the group consisting of trivalent cation salts, divalent cation salts, and combinations thereof.

8. The method of claim 7 wherein the trivalent cation salts include a cation selected from the group consisting of Al, Ga, In, Fe, Sb, and Bi.

9. The method of claim 1 wherein attaching multi-valent cations to the surface of the quantum dot nanocrystal surfaces includes the multi-valent cations becoming attached to the QD nanocrystal surfaces through pseudo-atomic layer deposition.

10. The method of claim 1 wherein forming the treated quantum dots emitting the non-varying intensity of first wavelength of light when subjected to a continuous exposure of the second wavelength of light includes the treated QDs emitting light selected from the group consisting of blue, green, and red color light when exposed to light in the ultraviolet (UV) spectrum.

11. The method of claim 1 wherein forming the treated quantum dots emitting the non-varying intensity of first wavelength of light when subjected to a continuous exposure of the second wavelength of light includes the treated QDs emitting a light color selected from the group consisting of red and green when exposed to a blue color light.

12. A method for forming a light emitting diode device with suppressed quantum dot photobrightening, the method comprising:

providing quantum dot (QD) nanocrystals having a surface, with a maximum cross-sectional dimension of 10 nanometers (nm), capable of emissions in the visible spectrum of light;

treating the quantum dot nanocrystal surfaces with a solution including a multi-valent cation salt;

heating the solution to a temperature in a range of 50 to 200 degrees C.;

in response to heating the solution, attaching elements to the surface of the quantum dot nanocrystals consisting of cations, to formed treated QDs with suppressed photobrightening;

depositing the treated QDs overlying a top surface of a light emitting diode (LED); and

,

forming an LED device emitting a non-varying intensity of a first wavelength light in the visible spectrum from the treated QDs when subjected to a continuous exposure of a second wavelength of LED light having an intensity of greater than 50 watts per square centimeter (W/cm²).

13. The method of claim 12 wherein providing the QD nanocrystals includes providing QD nanocrystals with a structure selected from the group consisting of a solitary core and core-single shell structure.

14. The method of claim 12 wherein providing the QD nanocrystals includes providing QD nanocrystals comprising a binary or binary alloyed material surface;

and,

wherein treating the QD nanocrystals with the solution includes treating the QD nanocrystal surface with a solution including divalent cation salts.

15. The method of claim 14 wherein the QD nanocrystal surface is selected from the group consisting of CdS, CdSe, CdTe, GaAs, InAs, InN, InP, ZnS, ZnSe, ZnTe, and combinations thereof.

16. The method of claim 12 wherein providing the QD nanocrystal includes providing QD nanocrystals with a tertiary or tertiary alloyed material surface;

and,

wherein treating the QD nanocrystals with the solution includes treating the QD nanocrystal surfaces with a solution including a material selected from the group consisting of trivalent cation salts, divalent cation salts, monovalent cation salts, and combinations thereof.

17. The method of claim 16 wherein the QD nanocrystal surface is selected from the group consisting of ZnSSe, ZnSeTe, ZnSTe, CdSSe, CdSeTe, CdSTe, ZnCdS, ZnCdSe, ZnCdTe, ZnCdSSe, ZnCdSeTe, InGaAs, GaAlAs, InGaN, CuInS₂, CuGaS₂, Cu(In,Ga)Se₂, Cu(Zn,Sn)Se₂, Cu(Zn,Sn)S₂, CuIn(Se,S)₂, CuZn(Se,S)₂, CuSn(Se,S)₂, Cu(Zn,Sn)(Se,S)₂, and combinations thereof.

18. The method of claim 12 wherein providing the QD nanocrystals includes providing QD nanocrystals having a Type III-V semiconductor surface;

and,

wherein treating the QD nanocrystals with the solution includes treating the QD nanocrystal surfaces with a solution including a material selected from the group consisting of trivalent cation salts, divalent cation salts, and combinations thereof.

19. The method of claim 18 wherein the trivalent cation salts include a material selected from the group consisting of Al, Ga, In, Fe, Sb, and Bi.

20. The method of claim 12 wherein attaching multi-valent cations to the surface of the quantum dot nanocrystals includes the multi-valent cations becoming attached to the QD nanocrystal surfaces through pseudo-atomic layer deposition.

21. The method of claim 12 further comprising:

prior to depositing the treated QDs overlying the top surface of the LED, mixing the treated QDs with a matrix material selected from the group consisting of epoxy, silicon, and acrylate based polymers to form a matrix paste; and

,

wherein depositing the treated QDs overlying the top surface of the LED includes depositing the matrix paste.

22. The method of claim 12 wherein forming the LED device emitting the non-varying intensity of the first wavelength light from the treated QDs when subjected to the continuous exposure of the second wavelength of LED light includes the treated QDs emitting a non-varying intensity of light selected from the group consisting of blue, green, and red color light when exposed to LED light in the ultraviolet (UV) spectrum.

23. The method of claim 12 wherein forming the LED device emitting the non-varying intensity of the first wavelength light from the treated QDs when subjected to the continuous exposure of the second wavelength of LED light includes the treated QDs emitting a non-varying intensity of light color selected from the group consisting of red and green when exposed to a blue color LED light.