Device including quantum dots

Patent metadata

Field	Value
Publication number	US-9496141-B2
Application number	US-201213468199-A
Country	US
Kind code	B2
Filing date	May 10, 2012
Priority date	Nov 11, 2009
Publication date	Nov 15, 2016
Grant date	Nov 15, 2016

Abstract

A method of making a device comprises forming a layer comprising quantum dots over a substrate including a first electrode, fixing the layer comprising quantum dots formed over the substrate, and exposing at least a portion of, and preferably all, exposed surfaces of the fixed layer comprising quantum dots to small molecules. Also disclosed is a method of making a device, the method comprising forming a layer comprising quantum dots over a substrate including a first electrode, exposing the layer comprising quantum dots to small molecules and light flux. A method of making a film including a layer comprising quantum dots, and a method of preparing a device component including a layer comprising quantum dots are also disclosed. Devices, device components, and films are also disclosed.

First claim

The invention claimed is:

1. A method of making a light emitting device comprising:
forming an electroluminescent emissive quantum dot layer over a substrate including a first electrode, wherein a quantum dot comprises a core comprising a first semiconductor material and a shell over at least a portion of an outer surface of the core, the shell comprising a second semiconductor material,
fixing the electroluminescent emissive quantum dot layer formed over the substrate, wherein fixing the layer comprises heating in a substantial absence of oxygen,
exposing at least a portion of exposed surfaces of the fixed electroluminescent emissive quantum dot layer to small molecules to treat the at least a portion of the exposed quantum dot surfaces with small molecules, wherein the small molecules are in liquid state, and wherein the small molecules comprise small polar molecules in liquid state, and
exposing all or a portion of exposed surfaces of the fixed electroluminescent emissive quantum dot layer to light flux in the presence of the small molecules.

2. A method in accordance with claim 1 wherein fixing the electroluminescent emissive quantum dot layer comprises heating in the substantial absence of oxygen at a temperature in a range from about 80° C. to about 180° C.

3. A method in accordance with claim 1 wherein a small molecule includes no more than 50 atoms.

4. A method in accordance with claim 1 wherein a small molecule has a molecular weight of less than or equal to 100 a.m.u.

5. A method in accordance with claim 1 wherein exposure to small molecules is carried out in air.

6. A method in accordance with claim 1 wherein exposure to small molecules is carried out in the absence of oxygen.

7. A method in accordance with claim 1 wherein exposure to small molecules is carried out at a temperature in a range from about 20° to about 80° C.

8. A method in accordance with claim 1 wherein exposure to small molecules is carried out at a pressure of about 1 atmosphere.

9. A method in accordance with claim 1 wherein exposure to small molecules is carried out at a pressure of less than 1 atmosphere.

10. A method in accordance with claim 1 wherein the light flux includes a peak emission wavelength in a range from about 365 nm to about 480 nm.

11. A method in accordance with claim 1 wherein the light flux includes a peak emission wavelength in a range from about 450 nm to about 470 nm.

12. A method in accordance with claim 1 wherein the light flux includes a peak emission wavelength that can excite at least a portion of the quantum dots.

13. A method in accordance with claim 1 wherein the light flux is from about 10 to about 100 mW/cm 2 .

14. A method in accordance with claim 1 wherein all or a portion of exposed surfaces of the fixed electroluminescent emissive quantum dot layer is exposed to small molecules for at least about 30 seconds.

15. A method in accordance with claim 1 further comprising forming a first layer comprising a material capable of transporting charge over the substrate including the first electrode prior to forming the electroluminescent emissive quantum dot layer.

16. A method in accordance with claim 1 further comprising forming a second layer comprising a material capable of transporting charge over the electroluminescent emissive quantum dot layer after exposure to small molecules.

17. A method in accordance with claim 1 wherein method steps following exposure to small molecules are carried out in absence of oxygen.

18. A method in accordance with claim 1 wherein the small molecules are included in a carrier medium.

19. A method in accordance with claim 1 wherein forming the electroluminescent emissive quantum dot layer comprises applying an ink comprising quantum dots and a carrier liquid and removing the carrier liquid.

20. A method in accordance with claim 1 wherein forming the electroluminescent emissive quantum dot layer comprises applying an ink comprising quantum dots and a carrier liquid and evaporating the carrier liquid.

21. A method in accordance with claim 20 wherein after evaporation of the liquid carrier, the electroluminescent emissive quantum dot layer is heated in absence of oxygen to remove carrier liquid.

22. A method in accordance with claim 1 wherein forming the electroluminescent emissive quantum dot layer comprises applying an ink comprising quantum dots and a carrier liquid and evaporating the carrier liquid by vacuum evaporation.

23. A method in accordance with claim 1 wherein the exposure step comprises exposing at least a portion of the exposed surfaces of the fixed electroluminescent emissive quantum dot layer to an atmosphere with a relative humidity from about 50% to about 85%.

24. A method in accordance with claim 1 wherein after the exposure step, the electroluminescent emissive quantum dot layer formed over the substrate is placed under vacuum of 10 −6 torr or better in absence of oxygen.

25. A method for improving the lifetime of a light emitting_device including an electroluminescent quantum dot emissive layer, the method comprising a method in accordance with claim 1 .

26. A method for reducing the charge trap density in a light emitting device including an electroluminescent emissive quantum dot layer, the method comprising a method in accordance with claim 1 wherein the method further comprises exposing exposed surfaces of the electroluminescent emissive quantum dot layer to small molecules and light flux to in an amount and for a period of time sufficient to reduce the charge trap density in the device.

27. A method in accordance with claim 1 wherein a small molecule comprises a lone electron pair.

28. A method in accordance with claim 1 wherein exposure to small molecules is carried out at a pressure greater than 1 atmosphere.

29. A method in accordance with claim 1 wherein the small molecules are included in a mist, vapor, spray, or gas flow stream.

30. A method in accordance with claim 1 wherein one or more ligands are attached to an outer surface of the quantum dot.

Assignees

• Kazlas Peter T
• Morris John Spencer
• Nick Robert J
• Popovic Zoran
• Stevenson Matthew
• Steckel Jonathan S
• Qd Vision Inc

Inventors

• Kazlas Peter T
• Morris John Spencer
• Nick Robert J
• Popovic Zoran
• Stevenson Matthew
• Steckel Jonathan S

Classifications

• H10P14/3461

  Nanoparticles · CPC title

• H10P14/3431

  Selenides · CPC title

• H10P14/3428

  Sulfides · CPC title

• H10P14/3402

  characterised by the chemical composition · CPC title

• H10P14/2901

  Materials · CPC title