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Reversible electro-optic device employing aprotic molten salts and method

a technology of electro-optic devices and molten salts, applied in the field of reversible mirrors, can solve the problems of increasing air conditioning requirements and costs, unfavorable environment, and partially effective effects

Inactive Publication Date: 2006-01-19
LOS ALAMOS NATIONAL SECURITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention is about a special device that can change the way it lets light pass through or reflects on it. This device contains two different metals and a chemical that can be oxidized. When an electric charge is applied, the metals can be deposited onto a surface and the chemical can change from a soluble state to a more solid state, which affects how much light passes through or reflects on the device. The invention can be used to create a reversible electro-optic device that can change its properties with an electric charge."

Problems solved by technology

Sunlight transmitted through windows in buildings and transportation vehicles can generate heat (via the greenhouse effect) that creates an uncomfortable environment and increases air conditioning requirements and costs.
These approaches are only partially effective because the window itself is heated and because these devices, such as electrochromic devices, are relatively expensive and exhibit limited durability and cycle life.
Another limitation of electrochromic devices is that many employ organic dyes that have limited stability to ultraviolet light; absorb light rather than reflect it and therefore only partially reduce solar thermal burdens; and do not offer privacy or complete opacity.
Certain liquid crystal-based window systems switch between transmissive and opaque / scattering states, but these systems require substantial voltages to maintain the transparent state.
Bright light from headlamps on following vehicles reflected in automobile rear and side view mirrors is annoying to drivers and creates a safety hazard by impairing driver vision.
Such devices do not provide close control over the amount of reflected light, and are expensive to fabricate since a very constant inter-electrode spacing is required to provide uniform dimming.
In prior art attempts to exploit reversible electrodeposition of a metal for light modulation, the deposits obtained on transparent substrates presented a rough and black, gray, or sometimes colored appearance (typical of finely-divided metals) and exhibited poor reflectivity and high light absorbance, especially when thick.
Warszawski (U.S. Pat. No. 5,056,899), which is concerned with displays, teaches that reversible metal electrodeposition is most appropriate for display applications, since significant disadvantages for transmission devices were given (e.g., the possibility of metal electrodeposition at the counter electrode).
Such teachings imply that the application of reversible metal electrodeposition to smart windows must involve light absorption by the finely divided electrodeposited metal, which would result in heating of the device itself and thus the space inside.
In addition to the desired electrodeposition of metals, competing and deleterious side-reactions may also occur.
These reactions decrease the current efficiency for metal electrodeposition.
Importantly, reversible mirror devices are volume-constrained and may rupture if even small amounts of gas are generated.
Other unwanted and deleterious side-reactions include formation of metal complexes with hydroxide and oxide ligands, and rapid oxidation of electrodeposited metal.
ein. Organic solvents, however, present their own set of problems for reversible mir
rors. These problems may include low solubility of charge carriers in organic solvents, poor conductivity, poor solubility of metal ions, low boiling points, toxicity, flammability, low electrochemical stability, low photostability, and poor seal tole

Method used

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  • Reversible electro-optic device employing aprotic molten salts and method
  • Reversible electro-optic device employing aprotic molten salts and method
  • Reversible electro-optic device employing aprotic molten salts and method

Examples

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example 1

[0068] An embodiment of a reversible mirror of the invention was fabricated as follows: two electrodes were prepared using 6×8 cm single-side planar ITO coated glass plates having a sheet resistivity of 7 Ω / square. Each plate was provided with a bus bar by attaching a copper electrical contact approximately 1 cm wide along the entire edge of the 6 cm end of each plate. The electrodes were then washed with water, methanol and acetone, and dried in a stream of warm air to remove any dust or grease.

[0069] An o-ring (2 cm internal diameter (ID) vycor rubber donut-shaped o-ring, 0.3 cm thick) was used as a gasket to seal one electrode to the other. A silver wire (5 cm long, 0.25 mm diameter, 99.9% metal purity) was inserted through the o-ring by first piercing a hollow needle through the o-ring, placing one end of the silver wire through the hollow needle, and then withdrawing the hollow needle from the o-ring. Approximately 0.4 mm of the silver wire protruded through the o-ring. The o-...

example 2

[0072] A second working embodiment of a reversible mirror of the invention was fabricated using the general procedure provided in EXAMPLE 1 but with a solution of 3-butyl-1-methylimadazolium bis(trifluoromethylsulfonyl)imide (also containing less than 1 ppm water) and 0.792 mol / L of iron (II) is (trifluoromethylsulfonyl)imide. An iron mirror was deposited at a potential of −1.2 Volts versus the silver reference electrode. Twenty minutes after the potential was removed, the iron mirror deplated spontaneously. Overall, this reversible mirror device exhibited good optical reflectance in the reflective state and good transparency in the non-mirrored state, and was switched repetitively between these two states without degradation of performance.

example 3

[0073] A third working embodiment of a reversible mirror of the invention was fabricated using the general procedure provided in EXAMPLE 1 but with a solution of solution of 3-butyl-1-methylimadazolium bis(trifluoromethylsulfonyl)imide containing less than 1 ppm water and 0.073 mol / L ferrocene was used. By contrast to EXAMPLE 2, the iron is initially present as ferrocene. An iron mirror was initially deposited at a potential of −1.5 Volts versus the silver reference electrode. This iron mirror was deplated at a potential of +0.4 Volts versus the silver reference electrode and redeposited at a potential of −1.2 Volts versus the silver reference electrode. Overall, this reversible mirror device exhibited good optical reflectance in the reflective state and good transparency in the non-mirrored state, and was switched repetitively between these two states without degradation of performance.

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Abstract

A reversible electro-optic device includes a medium of variable transmittance to light. The medium includes a soluble redox couple of a first soluble metal containing species and a second soluble metal containing species. The metal of the soluble redox couple is capable of being electrodeposited. The medium also includes one or more anodic compound(s) capable of being oxidized. An alternate medium includes a soluble metal-containing species and a soluble anodic compound, where the soluble metal-containing species includes metal capable of being electrodeposited, and the anodic compound is capable of being oxidized to a soluble oxidized anodic compound. Another electro-optic device includes a medium of variable reflection to light.

Description

RELATED CASES [0001] This application is a continuation of copending U.S. patent application Ser. No. 10 / 831,572, filed Apr. 22, 2004, entitled “REVERSIBLE ELECTRO-OPTIC DEVICE EMPLOYING APROTIC MOLTEN SALTS AND METHOD,” which is a divisional of U.S. patent application Ser. No. 10 / 430,780, entitled “REVERSIBLE ELECTRO-OPTIC DEVICE EMPLOYING APROTIC MOLTEN SALTS AND METHOD,” now issued as U.S. Pat. No. 6,862,125, all hereby incorporated by reference.STATEMENT REGARDING FEDERAL RIGHTS [0002] This invention was made with government support under Contract No. W-7405-ENG-36 awarded by the U.S. Department of Energy. The government has certain rights in the invention.FIELD OF THE INVENTION [0003] The present invention relates generally to reversible mirrors and more particularly to a reversible mirror employing aprotic molten salts and to molten salt electrolyte solutions. BACKGROUND OF THE INVENTION [0004] Sunlight transmitted through windows in buildings and transportation vehicles can g...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C07C277/02G02F1/1506
CPCG02F1/1506C07D295/023
Inventor WARNER, BENJAMIN P.MCCLESKEY, T. MARKBURRELL, ANTHONY K.HALL, SIMON B.
Owner LOS ALAMOS NATIONAL SECURITY