Electrochromic device containing color-tunable nanostructures

1. An electrochromic device, comprising:

a first transparent conductor layer;

a working electrode disposed on the first transparent conductor layer and comprising nanostructures, the nanostructures comprising at least about 40 wt. % of amorphous niobium oxide nanoparticles and about 60 wt. % or less of tungsten oxide nanoparticles having a cubic crystal lattice structure, based on the total weight of the nanostructures;

a counter electrode;

a solid state electrolyte layer disposed between the counter electrode and the working electrode; and

a second transparent conductor layer disposed on the counter electrode.

2. The electrochromic device of claim 1 , wherein;

the nanostructures comprise from about 40 to about 80 wt. % of the amorphous niobium oxide nanoparticles and from about 60 to about 20 wt. % of the tungsten oxide nanoparticles, based on the total weight of the nanostructures; and

the tungsten oxide nanoparticles are doped with cesium and have a cubic crystal lattice structure.

3. The electrochromic device of claim 2 , wherein the working electrode comprises:

from about 35 to about 25 wt. % of the cesium doped tungsten oxide nanoparticles; and

from about 65 to about 75 wt. % of the amorphous niobium oxide nanoparticles.

4. The electrochromic device of claim 1 , wherein:

the amorphous niobium oxide nanoparticles have an average particle size of from about 3 nm to about 5 nm; and

the tungsten oxide nanoparticles have an average particle size of from about 4 nm to about 6 nm.

5. The electrochromic device of claim 1 , further comprising a protective layer configured to reduce degradation of the nanostructured layer due to ultraviolet (UV) radiation.

6. The electrochromic device of claim 1 , wherein:

the electrochromic device has a transmitted haze of less than about 1.0%;

in a bright mode the electrochromic device transmits at least 50% of received visible light; and

in a dark mode the electrochromic device transmits 5% or less of received visible light.

7. The electrochromic device of claim 1 , wherein the counter electrode comprises at least one selected from: CeO 2 ; CeVO 2 ; TiO 2 ; indium tin oxide; indium oxide; tin oxide; manganese or antimony doped tin oxide; aluminum doped zinc oxide; zinc oxide; gallium zinc oxide; indium gallium zinc oxide; molybdenum doped indium oxide; Fe 2 O 3 ; and V 2 O 5 .

8. The electrochromic device of claim 1 , wherein:

the working electrode is configured such that the electrochromic device transmits light of a first color in a bright mode and a second color in a dark mode; and

at least one of the first color and the second color is disposed in a first Lab color coordinate box having A* color coordinates ranging from about zero to about −4.0, and B* color coordinates ranging from about 4.0 to about −2.0.

9. The electrochromic device of claim 8 , wherein at least one of the first color and the second color is disposed in a second Lab color coordinate box having A* color coordinates ranging from about −1.0 to about −3.0, and B* color coordinates ranging from about zero to about 2.0.

10. An electrochromic device comprising:

a first transparent conductor layer;

a working electrode disposed on the first transparent conductor layer and comprising nanostructures comprising nanoparticles configured such that the electrochromic device transmits light of a first color in a bright mode and a second color in a dark mode;

a counter electrode;

a solid state electrolyte layer disposed between the counter electrode and the working electrode; and

a second transparent conductor layer disposed on the counter electrode, wherein at least one of the first color and the second color is disposed in a first Lab color coordinate box having A* color coordinates ranging from about zero to about −4.0, and B* color coordinates ranging from about 4.0 to about −2.0.

11. The electrochromic device of claim 1 , wherein the nanostructures comprise molybdenum doped tungsten oxide nanoparticles.

12. The electrochromic device of claim 1 , wherein the electrochromic device is located in a window.

13. The electrochromic device of claim 10 , wherein the nanostructures comprise at least about 40 wt. % of amorphous molybdenum oxide nanoparticles and about 60 wt. % or less of tungsten oxide nanoparticles, based on the total weight of the nanostructures.

14. The electrochromic device of claim 10 , wherein both of the first color and the second color are disposed in the first Lab color coordinate box.

15. The electrochromic device of claim 10 , wherein at least one of the first color and the second color is disposed in a second Lab color coordinate box having A* color coordinates ranging from about −1.0 to about −3.0, and B* color coordinates ranging from about zero to about 2.0.

16. The electrochromic device of claim 15 , wherein both of the first color and the second color are disposed in the second Lab color coordinate box.

17. The electrochromic device of claim 10 , wherein:

the nanostructures are configured such that the electrochromic device reflects outdoor light of a third color in the bright mode and a fourth color in the dark mode; and

at least one of the third color and the fourth color is disposed in a third Lab color coordinate box having A* color coordinates ranging from about 1.0 to about −5.0, and B* color coordinates ranging from about zero to about −8.0.

18. The electrochromic device of claim 17 , wherein both of the third color and the fourth color are disposed in the third Lab color coordinate box.

19. The electrochromic device of claim 17 , wherein at least one of the third color and the fourth color is disposed in a fourth Lab color coordinate box having A* color coordinates ranging from about −1.0 to about −3.0, and B* color coordinates ranging from about −3.0 to about −5.0.

20. The electrochromic device of claim 19 , wherein both of the third color and the fourth color are disposed in the fourth Lab color coordinate box.

21. The electrochromic device of claim 10 , wherein the first color is a neutral gray color.

22. The electrochromic device of claim 10 , wherein:

the electrochromic device has a transmitted haze of less than about 1.0%;

in a bright mode the electrochromic device transmits at least 50% of received visible light; and

in a dark mode the electrochromic device transmits 5% or less of received visible light.

23. The electrochromic device of claim 10 , wherein the electrochromic device is located in a window.

24. A method of operating an electrochromic device, comprising:

operating the device in a bright mode, such that the device transmits light of a first color; and

operating the device in a second mode, such that the device transmits light of a second color,

wherein at least one of the first color and the second color is disposed in a first Lab color coordinate box having A* color coordinates ranging from about zero to about −4.0, and B* color coordinates ranging from about 4.0 to about −2.0.

25. The method of claim 24 , wherein both of the first color and the second color are disposed in the first Lab color coordinate box.

26. The method of claim 24 , wherein at least one of the first color and the second color is disposed in a second Lab color coordinate box having A* color coordinates ranging from about −1.0 to about −3.0, and B* color coordinates ranging from about zero to about 2.0.

27. The method of claim 26 , wherein both of the first color and the second color are disposed in the second Lab color coordinate box.

28. The method of claim 24 , wherein:

operating the device in the bright mode further comprises reflecting outdoor light of a third color;

operating the device in the dark mode further comprises reflecting outdoor light of a fourth color; and

at least one of the third color and the fourth color is disposed in a third Lab color coordinate box having A* color coordinates ranging from about 1.0 to about −5.0, and B* color coordinates ranging from about zero to about −8.0.

29. The method of claim 28 , wherein both of the third color and the fourth color are disposed in the third Lab color coordinate box.

30. The method of claim 28 , wherein at least one of the third color and the fourth color is disposed in a fourth Lab color coordinate box having A* color coordinates ranging from about −1.0 to about −3.0, and B* color coordinates ranging from about −3.0 to about −5.0.

31. The method of claim 30 , wherein both of the third color and the fourth color are disposed in the fourth Lab color coordinate box.

32. The method of claim 28 , wherein:

the first color is a neutral gray color;

the electrochromic device has a transmitted haze of less than about 1.0%;

in a bright mode the electrochromic device transmits at least 50% of received visible light; and

in a dark mode the electrochromic device transmits 5% or less of received visible light.

33. The method of claim 24 , wherein the electrochromic device is located in a window.