COLLOIDAL INFRARED REFLECTIVE AND TRANSPARENT CONDUCTIVE ALUMINUM-DOPED ZINC OXIDE NANOCRYSTALS

• US 20130266800A1
• Filed: 11/23/2011
• Published: 10/10/2013
• Est. Priority Date: 11/24/2010
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Milliron, Delia J., Buonsanti, Raffaella
• Granted Patent: US 8,961,828 B2
• Time in Patent Office: Days
• US Class Current: 428/328
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 9/02 Oxides; Hydroxides
• CPC Class Codes: C01P 2002/54 one element only
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2002/77 by unit-cell parameters, atom positions or structure diagrams
• CPC Class Codes: C01P 2002/82 by IR- or Raman-data
• CPC Class Codes: C01P 2002/84 by UV- or VIS- data
• CPC Class Codes: C01P 2002/85 by XPS, EDX or EDAX data
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C30B 29/16 Oxides
• CPC Class Codes: C30B 29/22 Complex oxides
• CPC Class Codes: C30B 7/14 the crystallising materials being formed by chemical reactions in the solution
• CPC Class Codes: H01B 1/02 mainly consisting of metals or alloys
• CPC Class Codes: H01L 31/022483 composed of zinc oxide [ZnO]
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof

Abstract

The present invention provides a method of preparing aluminum-doped zinc oxide (AZO) nanocrystals. In an exemplary embodiment, the method includes (1) injecting a precursor mixture of a zinc precursor, an aluminum precursor, an amine, and a fatty acid in a solution of a vicinal diol in a non-coordinating solvent, thereby resulting in a reaction mixture, (2) precipitating the nanocrystals from the reaction mixture, thereby resulting in a final precipitate, and (3) dissolving the final precipitate in an apolar solvent. The present invention also provides a dispersion. In an exemplary embodiment, the dispersion includes (1) nanocrystals that are well separated from each other, where the nanocrystals are coated with surfactants and (2) an apolar solvent where the nanocrystals are suspended in the apolar solvent. The present invention also provides a film. In an exemplary embodiment, the film includes (1) a substrate and (2) nanocrystals that are evenly distributed on the substrate.

Claims

1. A method of preparing aluminum-doped zinc oxide nanocrystals comprising:

injecting a precursor mixture of a zinc precursor, an aluminum precursor, an amine, and a fatty acid in a solution of a vicinal diol in a non-coordinating solvent, thereby resulting in a reaction mixture;

precipitating the nanocrystals from the reaction mixture, thereby resulting in a final precipitate; and

dissolving the final precipitate in an apolar solvent.

2. The method of claim 1 wherein the injecting comprises injecting the precursor mixture, wherein the zinc precursor is selected from the group consisting of zinc stearate, zinc acetylacetonate, and zinc acetate.

3. The method of claim 1 wherein the injecting comprises injecting the precursor mixture, wherein the aluminum precursor is selected from the group consisting of aluminum acetylacetonate, aluminum stearate, and aluminum oleate.

4. The method of claim 1 wherein the injecting comprises injecting the precursor mixture, wherein the amine comprises oleylamine.

5. The method of claim 1 wherein the injecting comprises injecting the precursor mixture, wherein the fatty acid is selected from the group consisting of oleic acid and stearic acid.

6. The method of claim 1 wherein the injecting comprises injecting the precursor mixture in the solution, wherein the vicinal diol is selected from the group consisting of 1,2-dodecanediol, 1,2-hexadecanediol, and 1-2 octanediol.

7. The method of claim 1 wherein the injecting comprises injecting the precursor mixture in the solution in the non-coordinating solvent, wherein the non-coordinating solvent is selected from the group consisting of octadecene, benzylether, and phenylether.

8. The method of claim 1 wherein the precipitating comprises:

washing the nanocrystals in the reaction mixture with a first apolar solvent;

dissolving the washed nanocrystals in a second apolar solvent; and

rinsing the dissolved nanocrystals in the first apolar solvent at least twice.

9. The method of claim 8 wherein the washing comprises washing the nanocrystals with ethanol.

10. The method of claim 8 wherein the dissolving comprises dissolving the washed nanocrystals in hexane.

11. The method of claim 8 wherein the dissolving comprises dissolving the washed nanocrystals in toluene.

12. The method of claim 1 wherein the dissolving comprises dissolving the final precipitate in the apolar solvent, wherein the apolar solvent is selected from the group consisting of hexane, toluene, and chloroform.

13. The method of claim 1 wherein the injecting comprises varying the temperature of the solution between 230°

C. and 280°

C.

14. The method of claim 1 wherein the injecting comprises varying the growth temperature of the solution between 210°

C. and 260°

C.

15. The method of claim 1 wherein the injecting comprises allowing the mixture, the solution, and the solvent to react for a time that allows for the incorporation of aluminum in the aluminum precursor into the crystal lattice of a zinc oxide resulting from the injecting.

16. The method of claim 1 wherein the injecting comprises allowing the mixture, the solution, and the solvent to react for 2 to 5 hours.

17. The method of claim 1 further comprising depositing the nanocrystals from the dissolved precipitate on a substrate, thereby resulting in at least one aluminum-zinc oxide nanoparticles film.

18. The method of claim 17 wherein the depositing comprises depositing the nanocrystals from the dissolved precipitate on the substrate, wherein the substrate is selected from the group consisting of glass, silicon, quartz, indium tin oxide, fluorine-doped SnO₂, and polar solvents.

19. The method of claim 17 further comprising removing organic ligands from the surfaces of the nanoparticles in the aluminum-zinc oxide nanoparticles film.

20. The method of claim 19 wherein the removing comprises performing thermal annealing on the nanoparticles in the aluminum-zinc oxide nanoparticles film.

21. The method of claim 19 wherein the removing comprises exchanging the organic ligands with an inorganic salt.

22. The method of claim 19 wherein the removing comprises exchanging the organic ligands with other organic ligands.

23. A dispersion comprising:

nanocrystals that are well separated from each other, wherein the nanocrystals are coated with surfactants; and

an apolar solvent wherein the nanocrystals are suspended in the apolar solvent.

24. The dispersion of claim 23 wherein the nanocrystals comprise aluminum-doped zinc oxide nanocrystals.

25. The dispersion of claim 23 wherein the surfactants comprise fatty acids.

26. The dispersion of claim 25 wherein the fatty acids are selected from the group consisting of oleic acid and stearic acid.

27. The dispersion of claim 23 wherein the nanocrystals are less than or equal to 50 nm in size.

28. The dispersion of claim 23 wherein the apolar solvent is selected from the group consisting of hexane, toluene, and chloroform.

29. A film comprising:

a substrate; and

nanocrystals that are evenly distributed on the substrate.

30. The film of claim 29 wherein the nanocrystals comprise aluminum-doped zinc oxide nanocrystals.

31. The film of claim 29 wherein the nanocrystals are coated with surfactants.

32. The film of claim 31 wherein the surfactants comprise fatty acids.

33. The film of claim 32 wherein the fatty acids are selected from the group consisting of oleic acid and stearic acid.

34. The film of claim 29 wherein the nanocrystals are less than or equal to 50 nm in size.

35. The film of claim 29 wherein the substrate is selected from the group consisting of glass, silicon, quartz, indium tin oxide, fluorine-doped SnO₂, and polar solvents.