Electrolyte and additive for controlling morphology and optics of reversible metal films
Dynamic windows with adjustable tint give users greater control over flow of light and heat. Reversible metal electrodeposition dynamic windows include (i) a transparent or translucent conductive electrode; (ii) an electrolyte solution in contact with the electrode, the electrolyte solution comprising metal cations that are reversibly electrodeposited onto the transparent electrode upon application of a cathodic potential; and (iii) a counter electrode. The electrolyte solution advantageously includes a small amount of an additive (e.g., an inhibitor, an accelerator, a leveler, or an organic or inorganic molecule that similarly serves to enhance the surface morphology of the metal cations during reversible metal electrodeposition onto the transparent electrode). Such enhancement of surface morphology during the reversible electrodeposition of the metal tinting layer over the electrode enhances one or more of color neutrality, transmittance characteristics of visible wavelengths (e.g., ability to achieve a near 0% transmission privacy state), infrared reflectance, or switching speed.
1. An electrochromic dynamic window article capable of reversible metal electrodeposition, comprising:
a transparent or translucent conductive electrode;
an electrolyte in contact with the transparent or translucent conductive electrode, the electrolyte comprising metal cations that can be reversibly electrodeposited onto the transparent or translucent conductive electrode; and
a counter electrode;
wherein the electrolyte comprises an anion selected for its ability to (i) maintain solubility of components in the electrolyte and (ii) minimize or prevent etching of the transparent or translucent conductive electrode;
wherein at least one of (i), (ii), (iii) or (iv):
(i) an RMS surface roughness of a reversibly deposited metal layer onto the transparent electrode has a value that is less than about 30 nm;
(ii) the dynamic window is configured to achieve a high infrared reflectance of wavelengths in a range of 700 nm to 1200 nm that is at least 30%;
(iii) wherein the dynamic window is configured to achieve color neutral characteristics with a chroma (C*) of less than 10;
(iv) wherein the dynamic window is configured to achieve color neutral characteristics with |a*| or |b*| values of less than 5, over an operative VLT range of the dynamic window.
2. The article as recited in claim 1 , wherein the electrolyte comprises perchlorate anions.
3. The article as recited in claim 1 , wherein the anion of the electrolyte comprises a polyatomic anion.
4. The article as recited in claim 3 , wherein the polyatomic anion comprises chlorine or sulfate.
5. The article as recited in claim 1 , wherein the electrolyte is acidic.
6. The article as recited in claim 1 , wherein the metal cations comprise Cu.
7. The article as recited in claim 1 , wherein the metal cations comprise Cu and at least one of Bi or Li.
8. The article as recited in claim 1 , wherein the electrolyte is an aqueous electrolyte solution.
9. The article as recited in claim 1 , wherein the transparent or translucent conductive electrode comprises Pt nanoparticles.
10. The article as recited in claim 1 , wherein the transparent or translucent conductive electrode comprises a transparent conducting oxide electrode which comprises at least one of indium tin oxide or fluorine-doped tin oxide.
11. The article as recited in claim 1 , wherein the electrolyte is aqueous and acidic, wherein the metal cations comprise Cu and at least one of Bi or Li, wherein the transparent or translucent conductive electrode comprises a transparent conducting oxide electrode that comprises Pt nanoparticles.
12. The article as recited in claim 1 , wherein the counter electrode comprises a same metal as the metal cation in the electrolyte.
13. The article as recited in claim 1 , wherein the counter electrode comprises a different metal as compared to the metal cations in the electrolyte.
14. The article as recited in claim 1 , wherein the electrolyte comprises an additive configured to enhance a surface morphology of deposited metal cations during reversible metal electrodeposition, so as to enhance one or more of color neutrality, transmittance of visible wavelengths, infrared reflectance, or switching speed of the dynamic window.
15. The article as recited in claim 14 , wherein the electrolyte additive comprises at least one of a polyol, an amine-based polymer, or a cellulose derivative.
16. The article as recited in claim 1 , wherein the RMS surface roughness of a reversibly deposited metal layer onto the transparent electrode has a value that is less than about 25 nm.
17. The article as recited in claim 1 , wherein the dynamic window is configured to achieve a near zero transmissivity to provide a privacy state, where transmission of visible light wavelengths after full tinting is about 1% or less.
18. The article as recited in claim 1 , wherein the dynamic window is configured to achieve a high infrared reflectance of wavelengths in a range of 700 nm to 1200 nm that is at least about 40%.
19. The article as recited in claim 1 , wherein the dynamic window is configured to achieve color neutral characteristics with a chroma (C*) of less than about 8.
20. The article as recited in claim 1 , wherein the dynamic window is configured to achieve color neutral characteristics with |a*| or |b*| values of less than 5, over an operative VLT range of the dynamic window.