EP0789858A1

EP0789858A1 - Electrochromic devices and methods of preparation

Info

Publication number: EP0789858A1
Application number: EP95940538A
Authority: EP
Inventors: Pierre-Marc Allemand; F. Randall Grimes; Anoop Agrawal; Barbara A. Bigelow; Andrew R. Ingle
Original assignee: Donnelly Corp
Current assignee: Magna Donnelly Corp
Priority date: 1994-10-26
Filing date: 1995-10-25
Publication date: 1997-08-20
Also published as: EP0789858A4

Abstract

Electrochromic devices and processes for preparing the same are provided which do not require a separate process step of ion intercalation by employing an electrochromically-inert reducing or oxidizing additive in the electrochemically active material or the electrolyte of the electrochromic devices. An electrochromic device is also disclosed having a conducting electrode (20) opposing a counter conducting electrode (21) with an electrochemically active polymeric layer (30) disposed on an opposing surface of one of said electrodes and an electrolyte (40) containing at least one redox active material contactingly disposed between the electrochemically active layer and another opposing surface of one of said electrodes, wherein at least one of the electrodes is transparent. Also disclosed is an electrochromic device that exhibits low light transmission or reflectivity with no applied potential or after removal of an applied potential.

Description

TITLE

ELECTROCHROMIC DEVICES AND METHODS OF PREPARATION

BACKGROUND OF THE INVENTION

Field of the Invention

This invention is directed to electrochromic devices having an effective amount of an electrochromically- inert reducing or oxidizing additive in the electrolyte to eliminate a separate step of changing the initial state of reduction or the state of oxidation of an electrochemically active layer, such as by ionic intercalation of the electrochemically active layer of those devices. This invention is further directed to electrochromic devices wherein the electrochemically active layer of the device is comprised of a mixture of an electrochemically active material and an electrochromically-inert reducing or oxidizing additive to eliminate the separate step of changing the initial state of reduction or the state of oxidation of an electrochemically active layer, such as by ionic intercalation of the electrochemically active material. The invention is also directed to processes of preparing the above-described electrochromic devices as well as a process for preparing an electrochemically active layer which does not require a separate step of changing the initial state of reduction or the state of oxidation of an electrochemically active layer, such as one involving ionic intercalation. Yet another aspect of this invention is directed to an electrochromic device, such as a rearview mirror or glazing, having two opposed conducting electrodes, at least one of which is transparent, with an electrochemically active polymeric layer disposed on an opposing surface of one of said conducting electrodes and an electrolyte containing at least one redox active material disposed between and in contacting relationship with the electrochemically active layer and an other opposing surface of one of said electrodes. In addition, the outer surface of each transparent conducting electrode can have a substrate disposed thereon, at least one of which is transparent. Another aspect of this invention is directed to an electrochromic device that exhibits low light transmission or reflectivity with no applied potential or after an applied potential is removed.

Related Prior Art

It is well known that light transmission and reflection can be variably controlled by electrochromic (EC) devices. It would be advantageous to use large area EC devices as variable transmission windows to reduce the energy consumption in buildings and automobiles.

Moreover, EC devices are used for displays, dynamic optical filters and automotive mirror applications. Thus, a continuing need exists for EC devices which can be produced in a cost effective manner.

A conventional EC device is comprised of two opposing substrates having electronic conductors coated on the inward facing surface of the substrates. At least one of the conductor coated substrates is transparent, and for an EC window device both conductor coated substrates are transparent. Typically, the inward facing surface of each conductor is coated with an electrochemically active material. The substrates are assembled to form a cell which is filled with an electrolyte that is in conductive contact with both layers of electrochemically active material. Devices of this type are disclosed, for example, in U.S. Patent No. 4,750,816, U.S. Patent No. 4,938,571, U.S. Patent No. 5,080,471, U.S. Patent No. 5,189,549, and U.S. Patent No. 5,215,821.

However, prior to assembling such electrochromic devices it has been often necessary to either reduce or oxidize the electrochemically active material such as by intercalation of a layer of electrochemically active material with ions by either chemical or electrochemical means. This step is employed to either reduce the electrochemically active material if cations are used or oxidize the material if anions are used. This is done to ensure that the electrochemically active materials in an electrochromic device having more than one type of electrochemically active material are all in a substantially equivalent state of light transmission, i.e.. they are either colored or clear.

For example, where the two layers of electrochemically active material are tungsten oxide and vanadium oxide it is known to intercalate the latter with Li⁺ ions prior to assembling the device. Similarly, U.S. Patent No. 5,215,821 discloses a device having electrochemically active material layers of tungsten oxide and Prussian blue, wherein the tungsten oxide is electrochemically reduced to a blue tungsten bronze by exposing the tungsten oxide electrode under negative potential to an acidic solution prior to assembling the device. This electrochemical intercalation of the tungsten oxide allows for the extraction of the protons from the tungsten oxide to intercalate the Prussian blue electrode after the device is assembled and a voltage is applied so as to obtain a Prussian blue of high transparency.

An EC device having polyaniline and tungsten oxide electrochemically active material layers is also known. Under ambient conditions polyaniline exists in its oxidized state and is colored. However, under ambient conditions, tungsten oxide is in its oxidized state, which is transparent. Tungsten oxide can be colored by injection of electrons (reduction) with concomitant intercalation of cations, such as Li⁺ or H⁺. As noted previously, in order for such an electrochromic device to function properly, both layers of electrochemically active material must be in a substantially similar state of light transmission, i.e.. when polyaniline is colored the tungsten oxide is colored or when polyaniline is clear the tungsten oxide is clear. This can be accomplished by reducing the polyaniline or the tungsten oxide, as appropriate prior to device assembly.

It is known to reduce the polyaniline coating by the separate step of intercalating the polyaniline with protons or by extracting anions therefrom prior to assembling the device. Upon reduction, the polyaniline becomes transparent. However, when stored under ambient conditions the polyaniline gradually oxidizes and acquires color. The tendency of polyaniline to oxidize creates processing disadvantages for such electrochromic devices since the reduced polyaniline must either be quickly assembled into the device or stored and/or processed under inert conditions. The intercalation of ions into an electrochemically active material may also be required in other electrochromic device constructions. In particular, EC devices having only one electrochemically active electrode, can be constructed where the electrochemical activity in the electrochemically active layer is balanced by a redox active material capable of electrochemical activity in the electrolyte, such as disclosed in U.S. Patent No. 4,671,619.

Electrochromic (EC) devices are useful for making anti¬ glare automotive mirrors, displays, windows and filters for a variable reflection or transmission of electromagnetic radiation. A number of EC devices have been suggested that are based on electrochemically active polymeric materials which are conducting and/or redox polymeric materials such as polyaniline, polypyrrole, polythiophene, polyimides, polyviologens, their derivatives, or composite materials, copolymers and blends that have at least one phase that is based on such polymers.

U.S. Patent No. 4,750,816 discloses an electrochromic element having a pair of electrodes, at least one of which is transparent, wherein each electrode is coated with an electrochemically active material on the opposing surfaces of the electrodes and a liquid or solid electrolyte is disposed between the coated electrodes. At least one of the coatings of electrochemically active material in this reference is composed of conducting and/or redox polymeric materials as described above. Similar devices are disclosed in U.S. Patent No. 4,960,324, U.S. Patent No. 5,189,549, U.S. Patent No. 5,209,871 and U.S. Patent No. 5,215,821. All these references disclose the use of two electrodes, each of which, are coated with an electrochemically active material. Other EC devices have been suggested wherein only one electrode is coated with an electrochemically active material, such as the polymeric materials described above. U.S. Patent No. 4,304,465, U.S. Patent No. 4,586,792 and U.S. Patent No. 4,749,260 are directed to transmissive panels having this type of construction. These references disclose electrolytes which consist of salts in organic solvents or acidic aqueous solutions. None of these references, disclose or suggest the use of an electrolyte with a redox material in the absence of a second electrode coated with an electrochemically active material.

U.S. Patent No. 4,671,619 discloses an electrical optical device having an electrochromic material layer and an electrolytic solution interposed between mutually opposed base plates, each having an electrode disposed on the surface thereof, wherein the electrolytic solution consists of a redox reaction promoter and a lactone solvent for dissolving the redox promoter. The reference discloses that exemplary electrochromic materials include 0₃, Mo0₃, Ti0₂, and lr₂0₃. This reference does not disclose the use of electrochemically active polymeric material.

An object of this invention is to provide an electrochromic device having an electrochemically active layer that does not require a separate step of changing the initial state of reduction or the state of oxidation of the electrochemically active material, such as by ion intercalation.

Another object of this invention is to provide a process for preparing an electrochemically active layer on a substrate which does not require a separate processing step of initially oxidizing or reducing the 13754

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electrochemically active material, such as by ion intercalation.

A further object of this invention is to provide a process for preparing an electrochromic device having an electrochemically active material which has been reduced or oxidized without the use of a separate processing step.

Yet another object of this invention is to provide an improved electrochromic device, particularly for rearview mirrors and glazing of significant surface area, such as those exceeding 100 cm².

Another object of this invention is to provide an electrochromic device having a low light transmission or reflectivity when no potential is applied or after an applied potential is removed.

SUMMARY OF THE INVENTION

This invention is directed to an electrochromic device comprising two opposed conducting electrodes, at least one of which is transparent, an electrochemically active layer disposed on an opposing face of one of said electrodes and an electrolyte disposed between said electrochemically active layer and an other opposing face of said electrodes. The electrochemically active layer is comprised of an electrochemically active material which possess electrochromic properties. By electrochromic properties, it is meant that the material reversibly varies color or transmission of light as a result of an externally applied voltage.

Conventionally, when electrochromic devices such as described above are assembled, then depending on the type of the devices used, one of the electrochemically active layers may be oxidized or reduced such as by intercalating ions therein by either chemical or electrochemical processes. After this operation the device is assembled by sandwiching the electrodes to form a cavity that is filled by the electrolyte. This invention provides electrochromic devices and processes for preparing the same which do not require a separate processing step to change the initial oxidation state or reduction state of an electrochemically active material, such as by intercalating the electrochemically active layer with ions.

In a first embodiment of this invention the electrochemically active layer is a mixture of an electrochemically active material and an electrochromically-inert additive selected from the group consisting of reducing agents and oxidizing agents. The electrochromically-inert reducing or oxidizing additive is present in an effective amount to reduce or oxidize the electrochemically active material to the desired initial reduced or oxidized state. If the electrochromically-inert additive is a reducing agent, then the electrochemically active material will be reduced, while the use of an oxidizing agent results in the oxidation of the electrochemically active material. The electrochromically-inert additive may not necessarily reduce or oxidize the electrochemically active material immediately, but instead the reduction or oxidation can occur over a period of time dependent on the conditions, such as temperature and pressure, to which the electrochemically active material is exposed.

In another preferred embodiment of this invention, the electrolyte contains an electrochromically-inert additive selected from the group consisting of reducing agents or oxidizing agents. Again, the electrochromically-inert additive is present in an effective amount to reduce or oxidize an electrochemically active material in said electrochemically active layer to a desired state of initial reduction or oxidation. In this embodiment, the additive in the electrolyte reduces or oxidizes the electrochemically active layer without any other adverse effects. This process of reduction or oxidation by the additive in the electrolyte may be assisted by heat or radiation or by cycling the device or by exposing device to an appropriate electromagnetic radiation or both. The electrochemically active layer can be organic or inorganic or composites of inorganic and organic materials.

The electrochromic device of the instant invention may be further comprised of a first substrate disposed on an outwardly facing surface of one of said electrodes and a second substrate disposed on an other outwardly facing surface of said electrodes. At least one of the substrates is transparent. If the electrochromic device is a window or glazing then both electrodes and substrates must be transparent.

The electrochromic devices of the above described embodiments of this invention may also further comprise another electrochemically active layer disposed on the other opposing face of said electrodes. It is preferable that the device of invention comprise at least two electrochemically active layers separated by the electrolyte or a single electrochemically active layer and an electrolyte containing an redox active material which is electrochemically active. The most preferred electrochromic device of this invention, has an electrochemically active layer of polyaniline or a polyaniline derivative and an electrolyte containing a viologen salt. The invention is also directed to a process for preparing an electrochemically active layer on a substrate comprising the steps of:

(a) forming a liquid mixture of an electrochemically active material and an electrochromically-inert additive selected from the group consisting of reducing agents and oxidizing agents;

(b) contacting the liquid mixture to the substrate [such as by coating] ; and

(c) optionally exposing said contacted substrate to a temperature for a sufficient length of time for the electrochromically- inert additive to reduce or oxidize the electrochemically active material. It is particularly preferred to employ this process to prepare polyaniline coatings in their reduced form on the conducting surface of a substrate. In the above- described process the coating is deposited either in a reduced form or in a partially reduced form that self reduces upon storing for a period. Again the process can be assisted by the application of heat or radiation or both, if so desired, although such assistance is not required.

In the above-described devices and processes of this invention an effective amount of electrochromically- inert additive is employed to ensure that the desired amount of initial reduction or oxidation of the electrochemically active material is achieved. Preferably, this means that a stoichiometric amount of additive is used compared to the amount of electrochemically active material present in the layer.

Another embodiment of this invention is directed to a process for preparing an electrochromic device having two opposed electrodes, at least one of which is transparent, an electrochemically active layer disposed on an opposing face of one of said electrodes and an electrolyte disposed between said electrochemically active layer and an other opposing face of said electrodes, said process comprising the steps of: (a) forming said electrochemically active layer on said opposing face of one of said electrodes by contacting said opposing face, (such as by coating) , with a liquid mixture of an electrochemically active material and an electrochromically-inert additive selected from the group consisting of reducing agents and oxidizing agents;

(b) optionally exposing said liquid mixture contacted opposing face to a temperature for a sufficient length of time for the electrochromically- inert additive to reduce or oxidize the electrochemically active material;

(c) assembling said electrodes in a spaced-apart opposing relationship with said electrochemically active layer facing said other opposing face of said electrodes to form a cell; and

(d) filling said cell with an electrolyte.

In addition, the invention is also directed to a process for preparing an electrochromic device having two opposed electrodes, at least one of which is transparent, an electrochemically active layer disposed on an opposing face of one of said electrodes and an electrolyte disposed between said electrochemically active layer and an other opposing face of said electrodes, said process comprising the steps of:

(a) forming said electrochemically active layer comprised of an electrochemical active material on said opposing face of one of said electrodes;

(b) assembling said electrodes in a spaced-apart opposing relationship with said electrochemically active layer facing said other opposing face of said electrodes to form a cell; (c) filling said cell with an electrolyte containing an electrochromically-inert additive selected from the group consisting of reducing agents and oxidizing agents; and (d) optionally exposing said filled cell to a temperature for a sufficient length of time for the electrochromically-inert additive to reduce or oxidize said electrochemically active material.

Yet another aspect of this invention is directed to an electrochromic device comprising a conducting electrode opposing a counter conducting electrode with an electrochemically active polymeric layer disposed on an opposing surface of one of said electrodes and an electrolyte containing at least one redox active material contactingly disposed between said electrochemically active polymeric material layer and an other opposing surface of one of said electrodes. At least one of the electrodes is transparent. The invention further relates to an electrochromic device described above having a first substrate disposed on a nonopposing surface of said conducting electrode and a second substrate disposed on a nonopposing surface of said counter conducting electrode, wherein at least one of the substrates disposed on the electrodes is transparent.

The electrochemically active polymers typically possess electrochromic properties and are typically electronic conductors or semiconductors. A wide range of electrochemically active polymers is known to those skilled in the art.

In this aspect of the invention, the electrolyte is comprised of at least one redox active material. This electrolyte may also be comprised of an ionic material. Moreover, the electrolyte can be a liquid or solid. The electrochromic behavior of the device can be derived from the layer of electrochemically active material or from the layer of electrolyte, or from both layers. By electrochromic behavior it is meant that the material reversibly varies color or transmission of light as the result of an externally applied voltage.

The electrolyte may provide either a source or a sink for ions which are inserted or extracted respectively from the electrochemically active polymeric material layer. In addition, the electrolyte may also provide a mechanism to balance the reaction that causes the change in color to occur in electrochemically active polymeric layer or that causes electroactivity in that layer.

The electrolyte contains a redox active material which can be either a positive redox active material or a negative redox active material. Exemplary positive redox active materials useful in this invention, include, without limitation, metallocenes, such as cobaltocenes, ferrocenes and their derivatives, N, N, N' , N' -tetramethylphenylenediamine (TMPD) , phenothiazines, dihydrophenazines such as 5,10-dihydro- 5,10-dimethylphenazine, reduced methylphenothiazone (MPT) , reduced methylene violet bernthsen (MVB) , verdazyls, iodides and bromides. On the other hand, exemplary negative redox active materials which may be employed in this invention include, without limitation, bipyridiniums (viologens) , pyraziniums, pyrimidiniums, quinoxaliniums, pyryliums, pyridiniums, tetrazoliums, verdazyls, quinones, quinodimethanes, tricyanovinylbenzenes, tetracyanoethylene, polysulfides and disulfides. The choice of the redox active material depends on the electrochemically active polymer and the desired rest state of the device, i.e.. dark or clear. When a negative electrochemically active polymer is employed then a positive redox active material is used in the electrolyte. Similarly, if a positive electrochemically active polymer is employed then negative redox active material is used in the electrolyte. If a dark colored rest state is desired, then the electrochemically active polymer and the redox active material should be selected such as when at rest (i.e.. no potential applied to the device) , at least one of the electrochemically active polymer or the redox active material is in its colored state. To achieve such a dark colored rest state, generally the redox potential of a negative electrochemically active material is greater than the redox potential of a redox active material or the redox potential of a positive electrochemically active material is less than the redox potential of the redox active material. Exemplary negative electrochemically active polymers include, without limitation, polyviologens, or polymers containing bispyridinium, pyridinium, pyrylium, pyrazinium, pyrimidinium, or quinoxalinium units, polyarylenes and polyheteroarylenes, such as, for example, poly (pyridine-2,5-diyl) , polythiophenes, poly(isothianaphtene) (PITN) , polyimides, polyquinones and polydisulfides. Examples of positive electrochemically active polymers include, without limitation, polyarylamines, such as polyanilines, polyarylenes, such as polyphenylenes or polyfluorenes, polyheteroarylenes such as polypyrroles, polyindoles, polythiophenes or PITN, polyarylenevinylenes, such as poly(para- henylene vinylene) (PPV) , polyheteroarylenevinylenes and ferrocene containing polymers.

The electrolyte of this invention may also contain other additives which are not electroactive or electrochromic. These additives can modify the ultraviolet, visible, or near infrared absorption of the device. For example, dyes can be added to electrolyte for tinting or other purposes. Exemplary dyes which may be employed in this invention include, without limitation, azo, phthalocyanine, nitroso, triphenyImethane, squarilium, transition metal complex, perylene, anthraquinone, coumarin, rhodamine and porphyrin dyes, and their derivatives.

Another aspect of this invention is directed to an electrochromic device having a low light transmission or reflectivity in the resting state, i.e., at zero applied potential. Such an electrochromic device comprises a conducting electrode opposing a counter conducting electrode with an electrochemically active material layer disposed on an opposing surface of one of said electrodes and an electrolyte containing at least one redox active material contactingly disposed between said electrochemically active material layer and an other opposing surface of one of said electrodes. At least one of said electrodes is transparent. Significantly, the redox potential of a negative electrochemically active material (e.g., W0₃) is greater than a redox potential of the redox active material (e.g., cobaltocene) so that when the electrochemically active material and redox active material are in contact, the device is in a low state of transmission or reflectivity when no potential is applied (i.e., fcr example, the cobaltocene spontaneously reduces the W0₃ layer) . Similarly, the same result can be obtained if the redox potential of a positive electrochemically active material (e.g., polyaniline) is lower than the redox potential of a redox active material (e.g., ferrocene). Generally, the difference in redox potential between the electrochemically active material and the redox active material will be at least about 0.02 volts, preferably about 0.1 volts. The electrochemically active materials employed in this electrochromic device include inorganic, organic or blends and composites of inorganic and organic electrochemically active materials.

The electrochromic devices of this invention can be employed to make variable reflectance EC mirrors (e.g. automotive rearview mirrors, etc.). EC mirrors can be obtained by depositing a reflecting layer on the outer face of a transparent substrate disposed on a nonopposing surface of either of the two electrodes. It is also possible to create an EC mirror by using a conductive reflective material for one of the electrodes so that the electrode acts as both a reflector and also as the electronic conductor. Another advantage of using a metallic substrate as a conductor is its high conductivity. For example, the specific conductivity of materials like aluminum, silver, gold, copper, stainless steel, rhodium and the like, is orders of magnitude larger than that of the known transparent oxide conductors. It is also possible to employ a reflector material and a transparent conductor together to create an EC mirror. This may be advantageously employed where there is some non-desirable interaction between the electrochemically active polymeric layer and the reflector material during processing or the operation of the device. Such composites result in a much higher conductive substrate as compared to a device that does not employ a reflector material. The electrochromic devices of this invention prepared in such a manner are useful for constructing larger devices that can color uniformly without a large potential drop in the electrode.

These and other objects, aspects, feature and advantages of the present invention will become 13754

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apparent from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a schematic view of an EC window device according to the present invention.

Figure 2 is a schematic view of an another embodiment of an EC window device according to the present invention.

Figures 3 and 4 are schematic views of alternative embodiments of an EC mirror device according to the present invention.

Figure 5 is a schematic view of another EC window device according to the present invention.

Figures 6, 7, 8, 9 and 10 are schematic views of several embodiments of EC mirrors according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to electrochromic devices which may be employed such as in vehicular rearview mirrors or glazing. The device of this invention has a conductive electrode opposed to a counter conductive electrode with a layer of electrochemically active material disposed on an opposing surface of one of the electrodes and an electrolyte disposed between the electrochemically active layer and an other opposing surface of one of the electrodes. At least one of the electrodes is transparent. It is preferable that the present invention further comprise a first transparent substrate that is disposed on the outwardly facing surface of a transparent electrode and a second substrate disposed on the outwardly facing surface of the other electrode. Both substrates and electrodes of the EC device of this invention are transparent when the EC device of this invention requires complete visual transmission, such as in the case of a window or glazing.

The EC devices of this invention generally have either two electrochemically active layers separated by an electrolyte or a single electrochemically active layer with an electrochemically active species in the electrolyte. A preferred aspect of this invention is directed to electrochromic devices and processes for preparing the same which eliminate the need for a separate step in the fabrication of EC devices. Before EC devices of the prior art are assembled and/or sealed, one of the electrochemically active coatings may be oxidized or reduced such as by intercalation with ions with concomitant loss or gain of electrons. In the operation of the device, these ions are transported back and forth by the application of the appropriate voltage between either two layers of electrochemically active material via an ion conductor in the electrolyte or by ion exchange between a single electrochemically active layer and an electrolyte. In one of these states, the device is colored and in the other state it is bleached or colored differently.

According to one aspect of this invention, it is not necessary to intercalate any of the layers in an EC device in a separate processing step. In one embodiment of this invention, ionic intercalation is achieved by using an electrochromically-inert reducing or oxidizing additive in the ion conducting/electrolyte layer. Depending on the selection of the additive, the time and temperature required to achieve the desired initial oxidization/reduction can be affected. A higher temperature can be used to accelerate the process. Also, depending on the additive type, the process may also be assisted by a radiation process such as IR, UV or microwave with or without heat. These electrochromically-inert additives are typically oxidizing or reducing agents. By electrochromically- inert, it is meant that these additives are sacrificial agents which do not participate in the electrochromic reaction and that their residues are not electrochromically active, i.e. , they do not undergo a reversible color changing reaction in the EC device when an appropriate voltage is applied. Furthermore, their continued presence in the assembly does not adversely affect the performance of the electrochromic device. Exemplary reducing agents, which may be organic, inorganic or organometallic reducing agents, include, without limitation, oxalic acid, ascorbic acid, and their salts, alcohols, hydrazines, mercaptans, amines, organo lithiums such as butyl lithium, borohydride and the like. Several examples of useful oxidizing agents include, without limitation, persulfates, peroxides, nitrosonium salts, and the like. The most preferred electrochromically-inert additive for use in this invention is ascorbic acid.

Another embodiment of this invention is directed to EC devices which eliminate the separate ion intercalation process of the electrochemically active material by using an electrochromically-inert additive in the film forming electrochemically active material. For example, a liquid mixture containing the electrochemically active material and the additive could be applied to a substrate to obtain a coating. The coating is deposited in a state where no further treatment is required to change its oxidation state for assembly into the device. For example, when polyaniline or its derivatives are used as one of the electrochemically active layers, then an electrochromically-inert reducing agent may be added to the liquid mixture which will be employed to deposit the coating on the substrate. Preferred additives for the reduction of polyaniline include, without limitation, hydrazine and its derivatives, acids such as ascorbic and oxalic acids, and their salts and derivatives, and the like.

Figure 1 illustrates an example of an EC window device of this invention having transparent conducting electrodes 20 and 21 coated, respectively, on the opposing surfaces of transparent substrates 10 and 11. Two layers, 30 and 31, of electrochemically active material are disposed on the inward facing surfaces of electrodes 20 and 21, respectively. Electrochemically active layers 30 and 31 are separated by electrolyte 40. In this embodiment of the invention, either layer 30 or 31 contains an electrochromically-inert additive selected from a group consisting of reducing agents and oxidizing agents. Generally the reducing or oxidizing additive is present in at least a stoichiometric amount required to substantially achieve the desired oxidation or reduction of the electrochemically active layer 30 or 31. Desirably, this amount is at least equal to the stoichiometric equivalent of the electrochemically active material that one seeks to reduce or oxidize. Preferably, the ratio of electrochromically-inert additive to the electrochemically active material is less than 10:1. However, any amount of electrochromically-inert additive may be employed which will reduce or oxidize the electrochemically active material so that a separate ion intercalation step is not required.

In an alternative embodiment of this invention, electrolyte 40 contains an electrochromically-inert additive. Typically, the electrochromically-inert additive is present in the electrolyte in an amount of about 0.01 to 10.0 % by weight preferably in the amount of about 0.1 to 1.0 % by weight of the electrolyte. Again, however, any amount of electrochromically-inert additive may be employed which achieves the desired reduction or oxidization of the electrochemically active material, so that a separate ion intercalation processing step is not required.

An alternative embodiment of an EC window device of this invention is shown in Figure 2. This device is similar to that illustrated in Figure 1 with the exception that only a single electrochemically active layer 30 is present and electrolyte 40 contains an electrochemically active redox promoter. As in Figure 1, the electrochromically-inert reducing or oxidizing additive may be contained in electrochemically active layer 30 or in the electrolyte 40 or in both.

Figures 3 and 4 illustrate EC mirror devices of the present invention. Figures 3 and 4 are identical to Figures 2 and 1, respectively, with the exception that a reflective layer 50 is disposed on the outward facing surface of substrate 10. However, it should be understood that reflective layer 50 could be substituted for either substrates 10 and 11, disposed on the outward facing surface of substrate 11, disposed between either substrate 10 and conductor 20 or substrate 11 and conductor 21. Moreover, it is also possible to substitute reflective layer 50 for either conductor layer 20 or 21 if the reflective layer is conductive.

Typically the substrates 10 and 11 of the EC device illustrated in Figure 1 are transparent glass or plastic such as, for example, acrylic, polystyrene, polycarbonate, allyl diglycol carbonate [CR39 available from PPG Industries, Pittsburgh, Penn.], SAN [styrene acrylonitrile copolymer] , poly(4-methyl-1-pentene) , polyester, polyamide, etc. It is preferable for the transparent substrates 10 and 11 to be either clear or tinted soda lime glass, preferably float glass. If plastic is employed, it is preferably abrasion protected and barrier protected using a hard coat of, for example, a silica/silicone antiabrasion coating, a diamond-like protection coating or their like, such as is well known in the plastic glazing art. Generally, the substrates have a thickness in the range of about 0.01 mm to about 10 mm, and preferably in the range from about 0.1 mm to 5 mm. However, any substrate of any thickness which will provide a functioning EC device may be employed.

The transparent substrates 10 and 11, both glass and plastic, may have a coating on the outward facing surface. This coating may be an antireflection coating, an antifogging coating, an antiabrasion coating, an ultraviolet absorber coating and mixtures thereof. The substrates may have a coating, tape or lamination which is an antilacerative, an antiscatter, a colored, an ultraviolet blocking or an IR blocking coating, tape or lamination or mixtures thereof. It is also possible to employ transparent substrates which are specific colored substrates, photochromic substrates, infrared absorbing substrates, reflecting substrates, ultraviolet absorbing substrates and mixtures thereof. The conducting electrodes 20 and 21 may be of the same or different material and can have different conductivities. At least one of the conducting electrodes must be transparent, although when the EC device is a window device as shown in Figure 1 then both conducting electrodes 20 and 21 must be transparent. The materials employed for the conducting electrodes are well known to those skilled in the art. Exemplary conducting electrode materials are coatings of doped indium oxide, doped tin oxide, doped zinc oxide and the like, as well as all thin metallic coatings that are substantially transparent, such as those of gold, silver, aluminum, nickel alloy, and the like. It is also possible to employ multiple layer coatings, such as those available from Libby Owens Ford (LOF) under the tradename of TEC-Glass^® or those available from PPG Industries under the tradenames SUNGATE^® 300 and SUNGATE^® 500. The preferred sheet resistance of these conductive coatings should be below 100 Ω/LJ.

The TEC-Glass^® and SUNGATE^® conductive coated glass comprises a multi-layer thin film structure, which includes a thin coating of fluroine-doped tin oxide with additional undercoating thin film layers disposed between the fluorine-doped tin oxide layer and the underlying glass substrate. This structure inhibits reflected color and increases light transmittance resulting in a non-iridescent glass structure having a low haze (typically less than 5%) . The multi-layer coating stack is made from an on-line (preferably in- bath) pyrolytically-coated (preferably by chemical vapor deposition) float glass. The layers undercoating the doped tin oxide typically comprise a silica/silicone layer and a tin oxide layer. Preferably, the transparent conducting electrode used in this invention is a thin layer of ITO (ln₂0₃ containing preferably approximately 5 to 20 mole % of Sn0₂) . Typically, the conducting electrodes 20 and 21 are disposed on a substrate of glass or plastic as a coating and the coating has a thickness in the range of about 5 nm to about 10,000 nm, and preferably about 10 nm to about 1,000 nm. However, any thickness of the conducting electrode coating may be employed that provides adequate conductance for the EC device and which does not appreciably interfere with the transmission of light where required.

The electrochemically active materials 30 and 31 which may be employed in the present invention are well known to those skilled in the art. These include inorganic, organic or blends and composites of inorganic and organic electrochemically active materials. Exemplary inorganic metal oxide electrochemically active materials include W0₃ , V₂0₅ , Mo0₃ , Nb₂0₅ , Ti0₂ , CuO , Ni₂0₃ , lr₂0₃ , Cr₂0₃ , Co₂0₃ , Mn₂0₃ , and the like .

The electrochemically active organic materials useful in this invention are generally polymers which possess electrochromic properties and are typically electronic conductors or semiconductors. A wide range of electrochemically active polymers is known to those skilled in the art. Exemplary electrochemically active polymers useful in the instant invention include, without limitation, polyphenylene vinylenes, polythienylene vinylenes, polyalkoxythienylene vinylenes, polyfurylene vinylenes, polythiophenes, polyisothianaphthenes, polyanilines, polyarylamines, polyindoles, polypyrroles, polyalkoxyphenylenes, polyphenylenes, polyperinaphthalenes, polynaphthylamines, polyvinylmetalocenes, carbon cluster (fullerness) and carbon cluster containing polymers, polyimides, polyviologens. Other electrochemically active polymeric materials which may be employed in the present invention include, without limitation, derivatives of the aforementioned polymers, such as those prepared by sulfonation or substitution, copolymers, blends and composites, where the matrix may be organic or inorganic but at least one of the components is from the polymers or their derivatives described above. Some typical examples of these composites and blends are polyaniline or polypyrrole with prussian blue, polyaniline with phthalocyanine and/or sulfonic acid containing polymers and polyaniline in a metal oxide matrix, such as Si0₂, Ti0₂, Zr0₂, V₂0₅, W0₃ and the like.

The preferred electrochemically active materials of the present invention is polyaniline and its derivatives, and W0₃. The electrochemically active material may further comprise tinting materials, heat stabilizers, spacers, UV absorbers/stabilizers and adhesion promoting agents, such as coupling agents, which, for example, may be silane coupling agents, titanium coupling agents, zirconium coupling agents, and the like.

The electrolyte 40 can be solid or liquid. The electrolytes which may be employed in this invention are known and either are readily available or can be prepared by those skilled in the art. An exemplary electrolyte of the present invention is propylene carbonate which contains a redox active material such as, for example, a viologen salt.

The electrolyte 40 may contain a redox active material which itself can be a salt (e.g., a viologen) or a nonsalt (e.g., ferrocene). Additionally, electrolyte 40 may contain a separate ionic source, such as, for example, tetraethylammonium perchlorate (TEAP) or LiC10₄. One manner of forming the electrolyte, for example, is by dissolving a viologen salt in propylene carbonate (PC) . In addition, a dissociable salt, such as a soluble lithium salt, may be added to the solution. It is important that the solvent and also the resulting solution should have a low affinity for the solid polymeric film 30 so that this film does not peel off the substrate or dissolve while the device is in service.

Suitable solvents for the electrolyte may be selected from acetonitrile, 3-hydroxyproprionitrile, methoxypropionitrile, 3-ethoxypropionitrile, 2- acetylbutyrolactone, propylene carbonate, ethylene carbonate, glycerine carbonate, tetramethylene sulfone, cyanoethyl sucrose, γ-butyrolactone, 2- methylglutaronitrile, N, N' -dimethylformamide, 3- methylsulfolane, glutaronitrile, 3,3'- oxydiproprionitrile, methylethyl ketone, cyclopentanone, cyclohexanone, benzoyl acetone, 4- hydroxy-4-methyl-2-pentanone, acetophenone, 2- methoxyethyl ether, triethylene glycol dimethyl ether, 4-ethenyl-l,3-dioxalane-2-one, 1,2-butylene carbonate, glycidyl ether carbonates (such as those commercially available from Texaco Chemical Company, Austin, Texas) and combinations thereof, preferred of which include propylene carbonate.

Monomers with the appropriate polymerization initiators can be utilized as the monomer composition so that this composition can be in-situ polymerized after the cell has been filled by radiation, heat, or electrogenerated initiators to form a solid electrolyte. Such processes are described, for example, in co-pending U.S. Patent Application Serial No. 08/023,675, filed February 26, 1993 and co-pending U.S. Patent Application Serial No. 08/193,557, filed February 8, 1994, both of which are hereby incorporated by reference as if their disclosure were fully set forth herein.

Regardless of the procedure followed, the electrolyte can consist of other additives, e.g. tinting materials, UV stabilizers/absorbers, heat stabilizers, infrared absorbing dyes, moisture scavengers, fillers, viscosity modifiers, etc. The electrolyte 40 can consist of a UV absorber, and the device can be oriented in use such that incident light passes through layer 40 before layer 30. This will cause the UV radiation component to be absorbed before the light reaches the polymer 30. Thus, devices can be fabricated where UV sensitive polymers are used in layer 30. An example is a window configuration where layer 40 faces the light source, e.g. the sun, during use. Another possibility is a UV- stable rearview mirror where layer 40 is used to attenuate the UV before the light reaches layer 30.

The UV spectral characteristics of the device of this invention can be tailored by using more than one UV stabilizer. For example, UV stabilizers available under the tradenames Uvinul^® 400 and Uvinul^® 3050 from BASF Corporation could be used either alone, or, for example, in a 1:1 mixture.

Although many materials known to absorb ultraviolet radiation may be employed herein, preferred ultraviolet stabilizing agents include "UVINUL" 400 [2,4- dihydroxybenzophenone (manufactured by BASF Corp. , Wyandotte, Michigan)], "UVINUL" D 49 [2,2' -dihydroxy- 4,4' -dimethoxybenzophenone (BASF Corp.)], "UVINUL" N 35 [ethyl-2-cyano-3,3-diphenylacrylate (BASF Corp.)], "UVINUL" N 539 [2-ethyl hexy1-2-cyano-3,3' - diphenylacrylate (BASF Corp.)], "UVINUL" M 40 [2- hydroxy-4-methoxybenzophenone (BASF Corp.)], "UVINUL" M 408 [^"2- ydroxy-4-octoxy-benzophenone (BASF Corp.)],

"TINUVIN" P [2- (2H-benzotriazole-2-yl) -4-methylphenyl

(manufactured by Ciba Geigy Corp., Hawthorne, New

York)], "TINUVIN" 327 [2- (3', 5' -di- t-butyl-2' - hydroxyphenyl) -5-chloro-benzotriazole (Ciba Geigy

Corp.)], "TINUVIN" 328 [2- (3' ,5' -di-n-pentyl-2' - hydroxyphenyl) -benzotriazole (Ciba Geigy Corp.)],

"CYASORB" UV 24 [2,2' -dihydroxy-4-methoxy-benzophenone

(manufactured by American Cyanamid Co., Wayne, New Jersey) ] , monobenzoates (available from Eastmann

Chemicals, Kingsford, Tennessee and Sandoz Chemical Corp., Charlotte, North Carolina), resorcinol monobenzoates, formamidines (available from Givaudan- Roure, Clifton, New Jersey) , phenylformamidine and combinations thereof, where a suitable range of the ultraviolet stabilizing agents is from about 0.2% (w/v) to about 40% (w/v) , with about 5% (w/v) to about 15% (w/v) being preferred. The ultraviolet stabilizing agent should be chosen with an eye toward avoiding an adverse affect on performance and electrolyte function.

In addition, ultraviolet absorbing layers may be coated onto, or adhered to, the first substrate and/or second substrate, and preferably the substrate closest to the source of UV radiation, to assist in shielding the electrochromic device from the degradative effect of ultraviolet radiation. Suitable ultraviolet absorbing layers include those recited in U.S. Patent 5,073,012 entitled "Anti-scatter, Ultraviolet Protected, Anti- misting Electro-optical Assemblies", filed March 20, 1990, the disclosure of which is incorporated by reference herein.

Examples of such layers include a layer of DuPont BE1028D which is a polyvinylbutyral/polyester composite available from E.I. DuPont de Nemours and Company, Wilmington, Delaware, and SORBALITE™ polymeric UV blockers (available from Monsanto Company, St. Louis, Missouri) which comprise a clear thin polymer film with UV absorbing chromophores incorporated, such as by covalent bonding, in a polymer backbone. The SORBALITE™ clear thin polymer film when placed on a surface of the substrate closest to the source of UV radiation (such as the sun) , efficiently absorbs UV light below about 370 mm with minimal effect on the visible region. Thickness of the SORBALITE^"™ film is desirably in the range of about 0.1 microns to 1000 microns (or thicker) ; preferably less than 100 microns; more preferably less than about 25 microns, and most preferably less than about 10 microns. Also, UV absorbing thin films or additives such as of cerium oxide, iron oxide, titanium oxide or such oxides with dopants can be used to protect the electrochromic device from UV degradation.

Polyaniline and many of its derivatives, which are the preferred electrochemically active polymeric materials of this invention, are transparent and almost colorless in the reduced state and when oxidized change to green and then to a blue color with further oxidation. When a viologen salt is dissolved in PC, it is colorless in its oxidized state. Therefore, when polyaniline is used as the coating material in layer 30, it is preferred that both components, i.e.. the polyaniline coating 30 and the electrolyte 40, be in the transparent state.

The EC window device shown in Figure 1 may be prepared, for example, according to the process of this invention. First, an electrochemically active material such as polyaniline may be used as layer 30 and tungsten oxide may be used as layer 31, while a lithium ion conductor may be employed as the electrolyte 40. A typical lithium ion conductor can be a liquid or solid. For example, a liquid lithium ion conductor can be made by dissolving a lithium salt into a polar solvent such as propylene carbonate. It is preferred, to employ two conductive substrates, for example, glass coated with doped tin oxide, doped zinc oxide, doped indium oxide, which have surface resistivities preferably below 100 Ω/Ώ. Indium oxide doped with tin and tin oxide doped with fluorine are available commercially. The latter is also sold under the trade names TEC-Glass^® and SUNGATE^® from Libby Owens Ford (LOF) and PPG Industries, respectively. One of the electrochemically active coatings, e.g., polyaniline, is deposited on the conductive side of one of these substrates. This can be done by chemical or electrochemical methods, which are known to those skilled in the art. The former is easily scalable to large-area substrates and amenable to commercial production at low costs. In the chemical method, a polyaniline is typically mixed in a liquid and then the liquid mixture is contacted with the substrate such as by casting, spinning, roller applying, spraying, dipping, or by similar wet chemical means. As the liquid evaporates, if an electrochromically-inert reducing agent is not present, then a green-blue color coating is left behind which, when left in air, continues to oxidize to a more blue color. Typically, the thickness of this coating will be between TO nm and 10,000 nm. However, the preferred range is between 50 and 1000 nm. On the other substrate, a coating of tungsten oxide (in the same thickness range as above) is deposited on the conductive side. This coating can be deposited by physical vapor deposition, chemical vapor deposition

(CVD) , plasma-assisted CVD and by wet chemical methods (e.g., sol-gel process). The advantage of the liquid casting process is low capital costs and the ability to make the coatings with mixed cations to tailor the optical, chemical, electrochemical or physical properties. After both the coatings are obtained, a cell is constructed such that both the coatings face inwards. If the ion conductor is a solid, then a lamination process can be used, or a hollow cavity with a predetermined thickness can be formed that can be filled by the liquid electrolyte or ion conductor. The ion conductor formulation can be used in the liquid form or, depending on the composition, it can be converted into a solid by reactions that may be assisted by radiation or heat or both. The construction and general assembly of mirrors and glazings are well known as disclosed, for example, in U.S. Patent No. 5,066,112 and U.S. Patent No. 5,239,406, the disclosure of both of which are incorporated by reference herein as if fully set forth.

For liquid electrolytes, the cell can be constructed in the following way. The electrochemically active material coated substrates are adhered together at the edges by an adhesive or sealant (forming a seal) , preferably with a slight offset to attach the conductive busbars and/or conducting leads. The separation between the substrates is maintained by putting spacers (such as microbeads, cylinders, etc.) either in the adhesive or between the two plates or by both methods. The space may also be maintained by stops such as tapes, shims, etc. Typically, the thickness of the cavity is in the range of 1 micrometer to 10,000 micrometers, although the preferred range is between 10 and 1000 micrometers and the most preferred is 50 to 500 micrometers. The area of the coatings that comes in contact with this edge sealant may have to be chemically modified so that good adhesion and a seal is obtained. Sometimes it may be necessary to chemically deposit (or modify) this area on the conductive substrate before putting down any of the electrochemically active coatings 30 or 31 for obtaining good sealing characteristics. One may even remove the coatings from this area before cell fabrication and then chemically treat this with modifiers, e.g., coupling agents, to improve adhesion. A good seal is important to form a device that will withstand the environment and have a long, useful life. Coupling agents, e.g., those based on silanes, aluminates, titanates, zirconates, etc. may be used including those such as indium and/or tin reactive sites to enhance adhesivity to ITO and tin oxide transparent conductors. One may also add these materials to the adhesives directly. The adhesives may also consist of fillers, stabilizers, colorants, etc. to enhance their appearance, physical and chemical properties. The adhesive may be organic, inorganic, thermoplastic, thermosetting, solventless or solvent- containing, or even double-sided tapes and adhesives that may be activated by temperature, radiation, etc.

The resulting cell may be backfilled by procedures such as described in the U.S. Patent No. 5,140,455, the disclosure of which is incorporated by reference as if fully set forth herein. That patent also describes a two-hole filling procedure which may be used if so desired. We have discovered that the cavity can also be filled by a capillary method. In this method, two holes at the two opposite ends of the cell are required. One of these holes is then submerged into the electrolyte. The other hole remains at the highest end of the cell. The cell starts to fill by a capillary action, and the air or inert gas [nitrogen, argon or their like] in the cell is expelled at the other (high) end. To obtain a good cell without any air or gas pockets, the parameters such as the size of the holes, cavity thickness, cell size, amount of cell to be submerged, etc., must be optimized. One may even assist this process by a positive pressure on the electrolyte after submerging one end of the cell. The electrolyte can consist of UV stabilizers, thermal stabilizers, non-chemically active dyes, fillers and other additives, but in addition to all these, in one embodiment of this invention it will also consist of at least one reducing or oxidizing agent as described above, i.e.. an electrochromically-inert reducing or oxidizing additive. A preferred exemplary electrochromically-inert additive, which may be added to the electrolyte is ascorbic acid. A preferred concentration is at least stoichiometrically equivalent to the amount of the reduction required in one of the coatings in the device, e.g., equivalent to the polyaniline content in the coating that is being reduced.

The device will usually appear colored initially after completion of filling according to the method of this present invention (due to the color of polyaniline) , but over a period of time it will bleach as polyaniline is reduced. For example, it may take up to or more than 24 hours at room temperature but only a few hours at an elevated temperature of approximately 100°C.

After this treatment, the devices can be operated by applying a negative potential to the W0₃ and a positive potential to the polyaniline side for coloration and the reverse for bleach.

If a solid electrolyte is desired one could commence with a monomer composition that could be polymerized by radiation (e.g., UV, IR microwave, etc.) or by elevating the temperature further. The preparation of a solid electrolyte can be readily achieved by those skilled in the art.

A similar method can be used for making EC devices as shown in Figures 2 and 4. An automotive mirror EC device as shown in Figure 4 using polyaniline as the layer 30 could be prepared in the following way. Typically, a conducting substrate is mirrored on the non-conductive side, and the polyaniline coating is deposited on the conductive side. In a variation, a non-conductive glass can be coated with a mirroring metal such as silver, aluminum, stainless steel, chrome or rhodium, etc., and the polyaniline coating can be deposited on top of this layer. Thus, the reflector or the mirror also works as the electronic conductor. To make the device as shown in Figure 4, the hollow cavity is formed as described earlier. The electrolyte typically consists of a polar solvent such as propylene carbonate, ionic salt and/or cathodic material (for a device containing polyaniline coatings) . This material could be a viologen salt. The electrolyte can also have non-electrochemically active dyes, UV stabilizers, heat stabilizers, fillers, etc. However, the choice of the electrochromically-inert reducing additive should be done carefully so that it does not interact with the cathodic material (in this case viologen salt) . The reactivity of the viologen or other cathodic salts towards the reducing additive will also change with the type of ion on the salt. For example, when viologen triflate and ascorbic acid are present in the electrolyte within suitable concentrations, the color of the electrolyte doesn't change instantaneously showing that the latter does not reduce the viologen. Again, as described earlier, after the device is filled and sealed, polyaniline is reduced in situ. The reduction time can be controlled by varying the temperature.

Another process of this invention for eliminating the separate ionic intercalation step is by putting an electrochromically-inert additive selected from a group consisting of reducing agents and oxidizing agents in the film forming electrochemically active material for one of the electroactive films. The cell is then assembled as described above and there is no need to add any further electrochromically-inert additive in the electrolyte. It may even be desirable that both methods are combined, i.e.. the additive is employed in the coating material and also the same or another additive or a mixture of these is added to the electrolyte. One of the advantages of putting the additive in the film forming material is the possibility of using this film for all thin film solid state devices. For example, a reduced polyaniline or a derivative of it can be deposited as an electroactive coating on a conductive layer employing the method of this invention. This reduced coating can then be put into a physical vapor or a chemical vapor deposition chamber to deposit the other layers to advantageously complete an EC device without the need for any further separate reduction step.

The other layers in such an EC device could, for example, consist of tantalum oxide as an ion conductor, tungsten oxide as a counter electrode and a metallic or transparent conductive coating as a electronic conductor, respectively. A suitably thick [such as of aluminum or silver of thickness of 400 A or greater] metallic conductor will give an EC mirror device.

Although polyaniline or a derivative of polyaniline is a preferred electrochemically active material for use in this invention, it is clear that this invention encompasses other electrochemically active materials. The conducting electrodes could be coated with only inorganic materials such as tungsten oxide, molybdenum oxide, vanadium oxide, iridium oxide, and nickel oxide, Prussian Blue or electrochemically active polymers, such as polyaniline. The conducting electrodes could - 36 -

also be coated with mixtures and composites where one of the components are such polymers. These coatings could also consist of electrochemically active polymers either heterogeneously or homogeneously dispersed in an ion conductive matrix. The matrix could be a thermoplastic or a thermoset polymer or it can be inorganic.

Another aspect of this invention is directed to an electrochromic device having a conductive electrode opposed to a conductive counter electrode with a layer of electrochemically active polymeric material disposed on an opposing surface of one of the electrodes and an electrolyte comprising a redox active material disposed between the electrochemically active layer and an other opposing surface of one of the electrodes. At least one of the electrodes is transparent. The electrolyte fills the void between the electrochemically active layer and the other opposing surface of the electrode and thus is in intimate contact with the opposing surface of the electrode. Significantly, in this aspect of the invention one of the two opposing surfaces of the electrodes of the inventive device is not coated with an electrochemically active material.

Figure 5 illustrates an example of an EC window device of this aspect of the invention having transparent conducting electrodes 20 and 21 coated, respectively, on the opposing surfaces of transparent substrates 10 and 11. A layer of electrochemically active polymeric material 30 is disposed on the surface of electrode 20 facing electrode 21 and an electrolyte 40 comprised of a redox active material is disposed between and in a contacting relationship with electrode 21 and electrochemically active polymeric material 30. The electrochemically active polymeric materials 30 which may be employed in this aspect of the invention are well known to those skilled in the art. Examples of such electrochemically active polymeric materials have been previously described herein. The preferred electrochemically active polymeric material of this aspect of the invention is an organic electrochemically active polymeric layer comprising polyaniline or its derivatives.

An example of an embodiment of an EC automotive rear view mirror of this invention is shown in Figure 6. The mirror device of Figure 6 is identical to the device of Figure 5, with the exception that the mirror device has a reflective coating 50 disposed on the outer surface of transparent substrate 10. The EC automotive mirror device of Figure 6 can be fabricated by taking a piece of transparent substrate 10 which has a transparent conductive coating 20 and silvering the non-conductive side of one of the substrates 10 or 11 to make it reflective and protected with a polymeric paint using standard wet chemical silvering procedures.

The window device of Figure 5 can also be prepared using the following steps by simply eliminating the aforementioned silvering step. The substrate/conducting electrode is then coated (on the conductive side) with one of the electrochemically active polymeric materials 30 such as, for example, polyaniline. This coating can be deposited by electro¬ chemical polymerization, by physical or chemical vapor deposition, or from a liquid phase, such as from a solution, dispersion, suspension or a melt of a polymer, or its like, or from a monomer, where the monomer will polymerize on the conducting electrode 20 disposed on the substrate 10. The medium for this liquid phase could consist in part or completely of a material, e.g., a monomeric composition, that could be further polymerized. After a layer of this medium is deposited as a coating on the substrate, then the coating is formed by the removal of volatile matter (if any) and/or by polymerizing (inclusive of crosslinking if any) this monomeric composition. The process of polymerization can be assisted by application of heat and/or radiation (e.g., UV, IR, microwaves, etc.). This polymerizable material may belong to the class of polymers or copolymers that are used as ion conductors such as polyethylene oxide, polypropylene oxide, polyacrylamide, polymers with sulfonic groups, etc. A preferred method to deposit this coating is by a liquid casting process. This method is easily scalable to large substrate areas and amenable to commercial production at low costs. The thickness of the coating can be between 0.01 and 10 micrometers, but the preferred thickness is in the range of 0.01 to 2 micrometers.

A cell is then constructed by using this substrate/conducting electrode/electrochemically active polymeric material laminated to another substrate 11 which has only a conductive coating 21. Both the conductive coated sides of the substrates face inward into the cell. The substrates can then be held together [if necessary, such as when the electrolyte to be used is a liquid] at the perimeter edges by a cured epoxy, for example, forming a seal, preferably with a slight offset to attach the bus bars and/or the conducting leads (not shown) . The substrates are separated a predetermined distance, typically 10-1000 microns, more preferably 25-500 microns and most preferred 50-150 microns. This separation can be accomplished, for example, by either dispensing spacers (e.g., beads, spheres or cylinders) in the seal material or between the two substrates, thus forming a hollow cavity. This cavity can be filled with an electrolyte 40 using the methods described in U.S. Patent No. 5,140,455, which is incorporated by reference herein as if fully set forth. The seal material (not shown) can be a thermoplastic or thermosetting plastic or an inorganic material, such as a low melting point glass. The cell spacing can also be controlled by using a laminatable or a thermosetting sheet or a double sided tape to form the seal for the cavity.

In this aspect of the invention, the electrolyte 40 contains a redox active material which itself can be a salt (e.g., a viologen) or a nonsalt (e.g., ferrocene). Additionally, as discussed above, electrolyte 40 may contain a separate ionic source and/or a dissociable salt.

As previously described, regardless of the procedure followed, the electrolyte can consist of other additives, e.g. tinting materials, UV stabilizers/absorbers, heat stabilizers, infrared absorbing dyes, spacers, moisture scavengers, fillers, viscosity modifiers, etc.

Figure 7 illustrates an alternative mirror device to that shown in Figure 6, wherein reflective coating 50 also serves as conducting electrode 20 and thus eliminates the need for a separate reflective coating. In an alternative embodiment shown in Figure 8, reflective coating 50 is disposed in-between substrate 10 and conducting electrode 20. Figures 9 and 10 illustrate additional alternative embodiments of EC mirror devices of this invention wherein the reflective coating 50 is disposed on the outward facing surface of substrate 11 or in-between substrate 11 and electrolyte 40, respectively. Polyaniline and many of its derivatives, are the preferred electrochemically active polymeric materials of this invention. For polyaniline coatings, the natural stable state in air is green or blue, i.e. , an oxidized state. Hence, for preparing the device of this aspect of the invention it is preferable to bleach the coating after it has been deposited so that the highest transmission of light can be maintained in the bleached state. This can be accomplished electrochemically or by using chemical reducing agents, such as, for example, sodium hydrosulfite, ascorbic acid, hydrazine or its derivatives in aqueous or nonaqueous solutions. However, as mentioned earlier for the highest transmission in the bleached state, the coating after reduction should then be maintained under inert atmosphere [nitrogen argon, or the like] such that during further processing it is not reoxidized.

Alternatively, polyaniline can be assembled into the cell assembly in the colored state, followed by the in- situ reduction of the coating within the assembly by exposing the interpane void within the cell to reducing conditions such as by filling the cell with a reducing solution. The cell is then drained of the reducing solution, washed and then stored under inert conditions until it is filled with the electrolyte composition.

On the other hand, the polyaniline coating can be prepared from a liquid mixture containing at least one reducing agent or the electrolyte 40 can contain the reducing agent so as to eliminate the separate step of reducing the polyaniline as previously described herein.

Another method to reduce the coatings is by a gas phase process either before or after the cell fabrication. The cell with the colored coating (or the coated substrate itself) is placed in a chamber. The chamber can then be evacuated to expel any oxygen containing gas such as air. A reducing gas such as hydrazine vapors is then introduced into the chamber to bleach the polymeric coating. If the coating is being reduced in a fabricated cell (before filling) , repeated evacuation of the chamber and purging with the reducing gas is preferred.

Another example of an embodiment of this invention is illustrated if the electrochemically active polymeric layer 30 is made out of polyvinylferrocene or polyisothianapthene (PITN) . For the former, the solution for the electrolyte layer 40 may consist of a viologen salt dissolved in propylene carbonate (PC) .

For the latter, PITN is dark blue in the neutral state and transparent in its oxidized state. A cell can be made with transparent PITN as layer 30 and the electrolyte layer 40 may consist of a ferrocene and a salt dissolved in PC. After the cell is filled and sealed, PITN reduces reversibly to a blue color when a negative potential is applied thereto.

Depending on the requirements, there are several choices that are available from which anodic and cathodic compounds can be chosen. Examples of such compounds can be found in the U.S. Patent No. 5,239,405, which is hereby incorporated by reference as if the disclosure therein where fully set forth.

As noted previously, another aspect of this invention is directed to an electrochromic device having a low light transmission or reflectivity in the rest state, i.e., at no applied voltage. This electrochromic device is illustrated by Figure 1 as previously described with the exception that layer 30 is an electrochemically active material and either (i) the redox potential of a positive electrochemically active material is less than the redox potential of the redox active material in electrolyte 40, or (ii) the redox potential of a negative electrochemically active material is greater than a redox potential of the redox active material in electrolyte 40.

The electrochemically active materials 30 which may be employed in the present invention are well known to those skilled in the art. Such materials include inorganic, organic or blends and composites of inorganic and organic electrochemically active materials. Exemplary inorganic metal oxide electrochemically active materials include W0₃, V₂0₅, Mo0₃, Nb₂0₅, Ti0₂, CuO, Ni₂0₃, lr₂0₃, Cr0₃, Co₂0₃, Mn₂0₃, and the like. The electrochemically active organic materials useful in this invention are generally polymers which have been previously described.

Significantly, the electrochromic devices of this invention having a low light transmission or reflectivity in the rest state employ an electrochemically active material 30 having a redox potential that differs from the redox potential of the redox active material in electrolyte 40 in the manner described above. The electrochemically active material and the redox active material may be chosen from a wide variety of materials so long as the above-described difference in redox potential is met. The electrochromic behavior of the device may be derived from the layer 30, or from the layer 40 or from both of them. In this embodiment of the invention, the electrochromic device has a low light transmission or reflectivity in the rest state, i.e., when no potential is applied. When a potential is applied the light transmission or reflectivity of the device will increase. The light transmission or reflectivity of the device will revert to a low level when the applied potential is removed.

The electrolytes useful in this invention, which have been previously described, contain a redox active material. If a solvent is used in the electrolyte, the solvent should have a low affinity for the electrochemically active material layer so that the layer does not peel off the electrode or dissolve.

The redox active materials useful in this embodiment of the invention are well known to those of ordinary skill in the art and may additionally contain a separate ionic source. A particularly preferred redox active material for use with a W0₃ electrochemically active material layer is selected from metallocenes and their derivatives, most preferably cobaltocene. It is also preferred to employ an ionic source with cobaltocene and its derivatives, such as, for example, LiC10₄, LiBF₄, LiPF₆, LiCF₃S0₃, Li(CF₃S0₂)₂N or mixtures thereof.

Tungsten oxide and similar metal oxides are transparent and colorless in their natural stable oxidized state and when reduced change to a dark color. For W0₃ coatings, the natural stable state in air after solgel deposition or PVD (plasma vapor deposition) is transparent, i.e., in an oxidized state. The redox potential (E_W03) of W0₃ is in the range of about 0.0V to about -1.2V. In a prior art electrochromic device, ferrocene may be used as the redox additive. Since the redox potential of ferrocene (E_FC = +0.5V) is higher than E_wo3, the device will stay in a bleached state after filling. Hence, in such a device, the absorption at rest (V=0) of the coating after device construction is usually the same as the absorption of the coating which was used to make the device. However, if cobaltocene is used instead of ferrocene, the device will spontaneously color, since the redox potential of cobaltocene (E_CC=-1.1V) is lower than the coloration potential of the W0₃ film.

Polyaniline and many of its derivatives are transparent and almost colorless in the reduced state. When oxidized, polyaniline and its derivatives change to green (at about +0.2V) and then to a blue color with further oxidation. Hence, for the electrochromic device, a redox additive which is a good oxidizing agent for polyaniline will generally be selected to obtain a low light transmission or reflectivity device when no potential is applied. For example, the oxidized form of polyaniline can be used, in conjunction with the reduced form of the appropriate redox additive, such as ferrocene (E_Fc=+0.5v) . After filling of the device, it will remain in a dark state. When a negative potential is applied to the polyaniline (PANI) electrode of such a device, it will bleach, since PANI is reduced and ferrocene oxidized to ferrocenium cation at the other electrode. Disconnecting the leads will cause the device to color again, as ferrocenium will oxidize PANI to its colored state.

The electrochromic device of this invention having a low light transmission or reflectivity in the rest state may be prepared in the same manner as previously described. The only requirement is that the redox potential of the electrochemically active material must be matched with the redox potential of the redox active material as described above.

The EC devices of this invention are particularly useful as electrochromic mirrors or automotive glazings, such as sun roofs, sun visors, shade bands, or windows, like windshields, side windows or back lights.

The electrochromic mirrors of the present invention are suitable for use as automotive electrochromic rearview mirrors (e.g.. truck mirrors, interior and exterior mirrors for motor vehicles) including interior rearview mirrors and exterior flat, convex and aspherical automotive mirrors, architectural mirrors or specialty mirrors, like those useful in aeronautical, periscopic or dental and medical applications.

In addition to electrochromic automotive glazings and mirrors, electrochromic devices, such as architectural glazings, like those useful in the home, office or other edifice; aeronautical glazings, such as those which may be useful in aircraft; electrochromic optically attenuating contrast filters, such as contrast enhancement filters, suitable for use in conjunction with cathode ray tube monitors and the like; electrochromic privacy or security partitions; electrochromic solar panels, such as sky lights; electrochromic information displays; and electrochromic lenses and eye glass, may also benefit from that which is described herein.

The examples which follow are intended as an illustration of certain preferred embodiments of the invention, and no limitation of the invention is implied.

Example 1

Preparation and Reduction of Polyaniline Coatings in One Step

Polyaniline thin coatings were obtained in their reduced form directly from a liquid mixture containing polyaniline. When a stoichiometric amount or an excess amount of electrochromically-inert reducing additive, such as phenylhydrazine, was added to a 2% (w/v) mixture of polyaniline in 88% aqueous formic acid, the mixture changed slightly in color. This composition was used to spin cast or dip coat glass substrates to give very light green films. These polyaniline films turned completely colorless and transparent after heating at about 100°C in vacuum or in air for a short time. The FT-IR spectra of these films were identical to those reported in the literature for leucoemeraldine base, i.e.. the reduced form of polyaniline (I. Harada, Y. Furukawa, F. Ueda, Synth. Met. 1989, 29. E303.) The films turned blue upon prolonged exposure to air.

Example 2

Preparation and Reduction of Polyaniline Coatings in One Step with Phenylhydrazine, and Fabrication of an EC Mirror

A liquid composition of partially reduced polyaniline was prepared by adding 3 L of a liquid mixture of 10% phenylhydrazine in aqueous formic acid to 5 mL of 2% (w/v) polyaniline mixture in 88% formic acid. The liquid composition was spin cast on half wave (HW) ITO glass (about 12-15 ohms/G, about 10x2.5x0.063 in.), mirrored on the non-conductive side, and then dried at about 70°C in a vacuum oven to give a colorless and transparent film of leucoemeraldine base.

Another HW ITO conductive glass substrate of the same size was used as the counter electrode. The cell was assembled under argon by spacing apart these two substrates at the edges with an epoxy adhesive containing 53 μm glass beads spacers. The substrates having the same dimensions, they were slightly offset to provide for a place to attach the electrical leads. The epoxy was thermally cured at 120°C for 1 hour under inert atmosphere. The cell was vacuum backfilled with an electrolyte consisting of ethyl viologen diperchlorate (0.1 M) , lithium perchlorate (1.0 M) , 6% (w/w) Uvinul^® 400 in propylene carbonate. When +1.0 V was applied to the polyaniline coated electrode, the reflectivity of the cell changed from 65 %R to 11 %R (measured at 550 nm) in about 12 seconds. When -0.3 V was applied, the reflectivity changed from 11 %R to 65 %R in about 16 seconds.

Example 3

Preparation and Reduction of Polyaniline Coatings in One Step with Ascorbic Acid, and Fabrication of an EC Mirror

Polyaniline thin coatings were obtained in their reduced form directly from a liquid mixture in the following manner. When 1% of L-ascorbic acid was added to a 1.5% (w/v) liquid mixture of polyaniline in 88% aqueous formic acid, the mixture became more viscous and changed slightly in color (λmax = 806 nm) . This liquid mixture was used to spin cast thin films of polyaniline on mirrored HW ITO glass substrates (2x10 in.). These polyaniline films were light green in color. The FT-IR spectra of these films showed the presence of polyaniline in its emeraldine and leucoemeraldine oxidation states, and residual ascorbic acid. The films turned completely transparent after washing with methanol. After washing with methanol, the FT-IR spectra were identical to those reported in the literature for leucoemeraldine base. The films turned blue in a few days upon exposure to air.

The light green polyaniline coatings were dried in air, rinsed with methanol and dried in nitrogen. These coatings were then assembled into cells. Another HW ITO conductive glass substrate of the same size was used as the counter electrode. The cell was assembled by spacing apart these two substrates at the edges with an adhesive glue containing 105 μm glass beads spacers. The substrates having the same dimensions, they were slightly offset to provide for a place to anchor the electrical leads. The epoxy was thermally cured at 120°C for 1 hours under normal atmosphere. The cell was vacuum backfilled with an electrolyte consisting of a 0.1M solution of ethyl viologen triflate in propylene carbonate (PC) containing 6% (w/w) Uvinul^® 400. After filling, the cell was sealed and placed in an oven at 100°C for 4 hours. When +1.0 V was applied to the polyaniline coated electrode, the reflectivity (photopic filter) of the cell changed from 66.1%R to 10.7%R in about 5.2 seconds. When -0.3 V was applied, the reflectivity changed from 10.7%R to 66.1%R in about 11.3 seconds. When a similar EC cell was constructed eliminating the methanol rinsing step and was tested as described above, the cell colored from 63.7% to 17.2% in 8.8 seconds.

Example 4

EC Device with a Polyaniline Coating That Is Reduced with an Additive Containing Electrolyte

An electrochromic vehicular rearview mirror was constructed using an EC device prepared in the following manner. A 2% (w/v) liquid mixture of polyaniline (PANI) was made by stirring 20g of PANI (Emeraldine Base) in 1000 mL 88% aqueous formic acid (FA) , overnight at room temperature. The liquid mixture was filtered through a 1.5 μm glass filter to remove coarse residues. This liquid mixture did not turn into a gel on standing even after one year. A 1.3% (w/v) solution of PANI in 88% aqueous formic acid was made by diluting the appropriate amount of this 2% (w/v) liquid mixture with formic acid. A thin film of polyaniline was spin-cast onto a conducting substrate from this 1.3% aqueous formic acid liquid mixture. The substrate was half wave ITO glass, mirror shaped, about 10x2.5x0.063 in. in size, and mirrored on the non-conductive side. The green polyaniline coating was allowed to dry for several hours under normal atmosphere conditions, where it changed into a dark blue film.

These polyaniline coated glass substrates were assembled into cells. Another HW ITO conductive glass substrate of the same size was used as the counter electrode. The cell was assembled by sealing these two substrates at the edges with an epoxy adhesive containing 105 μm glass beads spacers. One hole was left in the glue to allow the vacuum backfilling of the cell with the electrolyte. The substrates having the same dimensions, they were slightly offset to provide for a place to anchor the electrical leads. The epoxy was thermally cured at 120°C for 1 hour under normal atmosphere. The cell was vacuum back filled with an electrolyte consisting of 34g of propylene carbonate (PC), 1.4g of ethyl viologen triflate, 2.0g of Uvinul^® 400, and 0.036g of ascorbic acid. The filling hole was plugged with a UV curable adhesive (Sarbox^® 500 containing 4% (w/w) Irgacure^® 184) and the dark blue cell was placed in an oven at 100°C for 4 hours. The cell became substantially colorless. When +1.0 V was applied to the polyaniline coated electrode, the reflectivity (photopic filter) of the cell changed from 74.9%R to 8.4%R. When -0.3 V was applied, the reflectivity went back to 74.9%R. The cell colored from 60% to 10% in about 9.9 seconds and bleached from 10% to 60% in about 12.6 seconds. The electrochromic rearview mirror constructed with this device continued to show excellent performance after 60,000 cycles at room temperatures. The mirror was successfully test 13754 P 9

- 50 -

driven in an automobile and exhibited heat stability, UV stability and general performance suitable for both interior and exterior use on an automobile.

Example 5

EC Device with a Tungsten Oxide Coating and a Polyaniline Coating That Is Reduced with an Electrolyte Containing an Additive

A thin film of polyaniline was spin-cast onto a conducting substrate from the 1.3% aqueous formic acid liquid mixture employed in Example 4. The substrate was half wave ITO glass, mirror shaped, about 10x2.5 in. and mirrored on the non-conductive side. The green polyaniline coating was allowed to dry for several hours under normal atmosphere conditions, where it changed into a dark blue film.

An electrochromic film of tungsten oxide/lithium oxide composite prepared by first preparing a solution of 11.7g of peroxytungstic acid ester, [which may be prepared according to the disclosure of U.S. Pat. No. 5,252,354, which is incorporated by reference herein] and 0.16 g of lithium ethoxide in 100 mL of reagent grade ethanol. This sol-gel solution was then spun onto a conducting substrate. The substrate was half wave ITO glass, of the same size as the polyaniline coated substrate. The transparent film thus deposited was not fired at high temperature but simply allowed to dry a few hours at room temperature under normal atmospheric conditions.

This W0₃ coated HW ITO conductive glass substrate was used as the counter electrode for previously made polyaniline coated glass substrate. The cell was assembled by sealing these two substrates at the edges with an epoxy adhesive containing 105 μ glass beads - 51 -

spacers. One hole was left in the glue to allow the vacuum backfilling of the cell with the electrolyte. The substrates having the same dimensions, they were slightly offset to provide for a place to anchor the electrical leads. The epoxy was thermally cured at

120°C for 1 hour under normal atmosphere. The cell was vacuum back filled with an electrolyte consisting of 30g of propylene carbonate (PC), 3.9g of lithium triflate, 1.8g of Uvinul^® 400, 0.04g of ascorbic acid, and 0.25g of water. The dark blue cell was placed in an oven at 100°C. After 4 hours, the cell was colorless. When +1.2 V was applied to the polyaniline coated electrode, the reflectivity (photopic filter) of the cell changed from 60%R to 10%R in about 9.2 seconds. When -0.6 V was applied, the reflectivity changed from 10%R to 40%R in about 2.2 seconds.

Example 6 EC Mirror with a Tungsten Oxide Coating

An electrochromic film of tungsten oxide was coated, as given in Example 5, on half wave ITO coated soda lime glass substrate having an automotive rearview mirror shape of about 10x2.5 in. To this, a second half wave ITO conductive glass substrate was laminated to form a cell with the two substrates spaced apart at their periphery with an epoxy adhesive seal containing 88 μm glass bead spacers. One hole was left in the glue to allow the vacuum backfilling of the cell with the electrolyte. The substrates having the same dimensions, they were slightly offset to provide for a place to attach the electrical leads. The epoxy was thermally cured at 120°C for 1 hour under normal atmosphere. The cell was vacuum backfilled with an electrolyte consisting of 13.5g of propylene carbonate, 18.9g of tetramethylene sulfone, 0.23g of ferrocene, 0.03g of lithium perchlorate, 0.09g of lithium tetrafluoroborate, 1.64g of Uvinul 400, and 0.0172g of ascorbic acid. The filling hole was plugged with a UV curable glue (Sarbox 500 containing 4% (w/w) Irgacure 184) and the colorless cell was cycled by alternately applying -1.2 V and 0 V to the Tungsten Oxide coated electrode. After 75 cyles the cell remained blue in color. When -1.2 V was applied to the tungsten oxide coated electrode, the reflectivity (photopic filter) of the cell changed from 38.5%R to 12.1%R. When 0 V was applied, the reflectivity went back to 38.5%R. A similar device prepared without ascorbic acid changed from a colorless 80.4%R to 6.4%R with application of - 1.2 V to the tungsten electrode, and back to 80.4%R with application of 0 V.

Example 7 Same as Example 6 using Evaporated Tungsten Oxide

An electrochromic film of tungsten oxide, 500 nm thick, was prepared by e-beam evaporation on half wave ITO coated soda lime glass substrate having an automotive rearview mirror shape of about 10x2.5 in. To this, a second half wave ITO conductive glass substrate was laminated to form a cell with the two substrates spaced apart at their periphery with an epoxy adhesive seal containing 88 μm glass beam spacers. One hole was left in the glue to allow the vacuum backfilling of the cell with the electrolyte. The substrates having the same dimensions, they were slightly offset to provide for a place to attach the electrical leads. The epoxy was thermally cured at 120°C for 1 hour under normal atmosphere. The cell was vacuum backfilled with an electrolyte consisting of 13.5g of propylene carbonate, 18.9g of tetramethylene sulfone, 0.23g of ferrocene, 0.03g of lithium perchlorate, 0.09g of lithium tetirafluoroborate, 1.64g of Uvinul 400, and 0.0172g of ascorbic acid. The filling hole was plugged with a UV curable glue (Sarbox 500 containing 4% (w/w) Irgacure 184) and the colorless cell was cycled by alternately applying -1.2 V and 0 V to the Tungsten Oxide coated electrode. After 75 cycles the cell remained blue in color. When -1.2 V was applied to the tungsten oxide coated electrode, the reflectivity (photopic filter) of the cell changed from 50.9%R to 5.7%R. When 0 V was applied, the reflectivity changed back to 50.9%R.

Example 8

EC Mirror with a Polyaniline Coating

A film of polyaniline 220 nm thick, was prepared as given in Example 4, on half wave ITO coated soda lime glass substrate having an automotive rearview mirror shape of about 10x2.5 in. To this, a second half wave ITO conductive glass substrate was laminated to form a cell with the two substrates spaced apart at their periphery with an epoxy adhesive seal containing 105 μm glass bead spacers. One hole was left in the glue to allow the vacuum backfilling of the cell with the electrolyte. The substrates having the same dimensions, they were slightly offset to provide for a place to attach the electrical leads. The epoxy was thermally cured at 120°C for l hour under normal atmosphere. The cell was vacuum backfilled with an electrolyte consisting of ethyl viologen triflate (0.1M) in propylene carbonate containing 6% (w/w) Uvinul 400 and 0.4% (w/w) ascorbic acid. The concentration of ascorbic acid in this example is four times higher than used in Example 4. The increased concentration of ascorbic acid was employed to reduce the high end reflectivity of the mirror, such as is often preferred for exterior automotive mirrors. The filling hole was plugged with a UV curable glue (Sarbox 500 containing 4% (w/w) Irgacure 184) and the dark blue cell was placed in an oven at 100°C for 4 hours. The - 54 -

cell became totally colorless. The colorless cell was cycled by alternately applying 1.0 V and -0.3 V to the Pani coated electrode. After 500 cycles the cell remained blue in color. When 1.0 V was applied to the Pani coated electrode, the reflectivity (photopic filter) of the cell changed from 55%R to 5.7%R. When -0.3 V was applied, the reflectivity changed back to 55%R.

Example 9

EC Mirror with a Tungsten Oxide Coating

An electrochromic film of tungsten oxide was prepared as given in Example 5, on half wave ITO coated soda lime glass substrate having an automotive rearview mirror shape of about 10x2.5 in. To this, a second half wave ITO conductive glass substrate was laminated to form a cell with the two substrates spaced apart at their periphery with an epoxy adhesive seal containing 88 μm glass bead spacers. One hole was left in the glue to allow the vacuum backfilling of the cell with the electrolyte. The substrates having the same dimensions, they were slightly offset to provide for a place to attach the electrical leads. The epoxy was thermally cured at 120°C for 1 hour under normal atmosphere. The cell as vacuum backfilled with an electrolyte consisting of 13.5g of propylene carbonate, 18.9g of tetramethylene sulfone, 0.23g of ferrocene, 0.03g of lithium perchlorate, 0.09g of lithium tetrafluoroborate, 1.64g of Uvinul 400, and 0.02g of phenyl hydrazine. The phenyl hydrazine was added to reduce the high end reflectivity of the mirror. The filling hole was plugged with a UV curable glue (Sarbox 500 containing 4% (w/w) Irgacure 184) and the colorless cell was cycled by alternately applying -1.2 V and 0 V to the Tungsten Oxide coated electrode. After 250 cycles the cell remained blue in color. When -1.2 V - 55 -

was applied to the tungsten oxide coated electrode, the reflectivity (photopic filter) of the cell changed from 15.0%R to 2.3%R. When 0 V was applied, the reflectivity changed back to 15%R.

Example 10 Preparation of Coatings of Polyanilines

Coatings of polyaniline and its derivatives were prepared in several ways.

A. Electrochemical Polymerization

The first method was by electrochemical polymerization. Electrochemical polymerization of aniline on conducting glass was conducted as described in the literature (A.F. Diaz, J.A. Logan, J. Electroanal. Chem. 1980, 111. Ill) and (T. Kobayashi, H. Yoneyama, H. Tamura, J. Electroanal. Chem. 1984, 161. 419). The anode was a piece of ITO glass and the cathode was a platinum foil. A liquid mixture of aniline (1.5 M) in 3 M HCl, degassed by bubbling nitrogen into it, was electrolyzed by applying a constant potential of 0.9 V between the ITO anode and a platinum foil counter electrode. After 1 hour, the polyaniline (PANI) film was rinsed with deionized water and dried. The anode was also primed, for example with a solution of 3- aminoproplytriethoxysilane and indium acetylacetonate in ethanol to improve adhesion of the polyaniline film.

B. In situ Polymerization

The second method to make the polyaniline and other electroactive films was by in si tu polymerization. For example, a thin film of polyaniline was deposited on a conducting glass substrate by the following method. A cold liquid mixture of ammonium persulphate (3.l2g, 0.25M) in HCl (65mL 1.5M) rapidly added to a cold liquid mixture of aniline (2.86g, 0.5M) in HCL (65mL, 1.5M) and the resulting liquid mixture was quickly poured onto a clean substrate made of TEC 10 glass (12 x 12 in.) carefully maintained in a horizontal position. Conductive substrates suitable for electrochromic devices can be tin oxide coated glass (TEC 10 conductor coated glass of sheet resistance 10 ohms/square or TEC 20 conductor coated glass of sheet resistance 20 ohms/square) , but also ITO glass, metal coated glass or even bulk metals. The liquid mixture rapidly turned dark blue, and after 15 minutes, the mixture was washed off the surface of the substrate which was rinsed several times with HCl (1.5M), then isopropyl alcohol, and finally air dried. A homogeneous film of polyaniline was left on the surface of the conducting glass. Its thickness was about 850A, as measured with a surface profilometer. A method using sulfuric acid instead of hydrochloric acid has been described by T. Meisel, R. Braun, Proc. SPIE,

Vol. 1728, 200-210 (1992), while another method using other oxidizing agents is described in U.S. Pat. 4,842,383.

C. Liquid Casting

The third method was by liquid casting. For this method, polyaniline powder (Emeraldine base) was prepared according to the procedures found in the literature (Y. Cao, A. Andretta, A.J. Heeger, P. Smith, Polymers, 1989, 3_0, 2305). In a typical run, a solution of ammonium persulfate (57g, 0.25 mol) in 200 mL of 1.5M HCl was slowly added to a cooled solution of aniline (46.5g, 0.5 mol) in 500 mL of 1.5 M HCl, under inert atmosphere. The temperature of the reaction mixture should be maintained below +60°C, but preferably it should be chosen between 0°C and 20°C and kept constant during the entire period of addition (ca. lhr) and during one more hour after the end of the addition of the oxidant. In this example the temperature of the reaction mixture was maintained at approximately 0°C. The polyaniline (emeraldine hydrochloride) was collected by filtration of the mixture on a Bϋchner funnel, washed with deionized water (5x500mL) , then stirred 8 hours in 1 L of 3% aqueous ammonium hydroxide under inert atmosphere. The polyaniline was then filtered on a Bύchner funnel, washed with water (3x500mL) , washed with methanol (3x200mL) , and finally dried under dynamic vacuum at 60°C until a constant weight was reached (18.2g).

The same procedure was used to synthesize derivatives of polyaniline, as well as copolymers of aniline and substituted anilines such as o-anisidine, 2,5- dimethoxyaniline, o-toluidine, 2-ethylaniline, N- methylaniline, and others.

For example, the polymerization of o-anisidine was conducted as follows. A solution of ammonium persulfate (28.75g, 0.126 mL in 100 ml of 1.5 M HCl) was slowly added to a cooled solution of o-anisidine (30.87g, 0.251 mL in 400 mL of 1.5 M HCl), under an inert atmosphere. Again, the temperature of the reaction mixture should be maintained below +60°C, but preferably it should be chosen between 0°C and 20°C and kept constant during the entire period of addition and during one more hour after the end of the addition of the oxidant. In this case, the temperature of the reaction mixture was held at approximately 1°C. The poly(o-anisidine) was then filtered on a Bϋchner funnel, washed with water (3x300 mL) , and neturalized with 3% aqueous ammonium hydroxide. The polymer was then filtered on a Buchner funnel, washed with water (3x300mL) , washed with methanol (5xl50mL) , and finally dried under dynamic vacuum at 60°C until a constant weight was reached (7.75g). Polyaniline liquid mixtures were then made in organic solvents such as N- methylpyrrolidinone (NMP) (M. Angelopoulos, G.E. Asturias, S.P. Ermer, A. Ray, E.M. Scherr, A.G.

MacDiarmid, M. Akhtar, Z. Kiss, A.J. Epstein, Mol. Cryst. Liq. Cryst. 1988, 160. 151-163.) or 88% formic acid (A.G. Green, A.E. Woodhead, J. Chem. Soc. 1910, 97. 2388.). Other organic and mineral acids or mixtures can also be used as solvents such as 80% aqueous acetic acid, or 98% sulfuric acid.

For example, 20g of polyaniline (emeraldine base) prepared as above was stirred overnight in 1000 ml of 88% aqueous formic acid under inert atmosphere. The dark green liquid mixture so formed was filtered several times on 1.5 μm glass filter to remove residual solids. Similarly, 2g of poly(o-anisidine) was stirred in 60 mL of 88% aqueous formic acid for 5 hours and then filtered on 1.5 μm glass filter.

Polyaniline and other derivatives can also be made more mixable in a wide range of organic solvents or with other polymers when they are complexed with large ions. For example, polyanilines complexed with camphorsulfonic acid or dodecylbenzenesulfonic acid are soluble in chloroform and toluene, respectively (U.S. Patent Application, 1991, Serial No. 07/800,555 and 07/800,559. see also A.J. Heeger and also Y. Cao, P. Smith, A.J. Heeger, Synth. Met. 1992, 4_8» 91.). Blends of these materials can be made with several polymers, an example being polyvinylbutyral. The above described liquid mixtures can be used to form coatings by casting, wire or roller coating, spin coating, dip coating, curtain coating, spraying, or other standard techniques. Example 11 Reduction of Polyaniline Coatings

Electrochemically active polymeric coatings in general and polyaniline coatings in particular can be incorporated into a device either in their oxidized or their reduced form.

Method a: Incorporation in its Reduced Form In a number of the EC cells, polyaniline was incorporated into the device in its reduced form. Several reagents and procedures were used to reduce these films to a colorless state.

In one method, the colored polyaniline coatings were dipped into a freshly prepared solution of sodium dithionite (2% w/w) in deoxygenated water. Within a few minutes, depending of the coating thickness, the coatings became completely transparent. They were then rinsed with deoxygenated water, dried and stored under nitrogen.

In another method, the polyaniline films were reduced with L-ascorbic acid solutions. For example, the coatings can be dipped into an aqueous solution of ascorbic acid (4% w/w) . Within a few minutes, depending on the film thickness, the polyaniline films were partially reduced to a very light green state. Complete reduction was achieved by applying for a few seconds a negative potential to the film, while a stainless steel counterelectrode dipping in the same ascorbic acid solutions was connected to the positive potential of a power supply. The reduced polyaniline films were rinsed with deoxygenated water, dried and stored under nitrogen. Alternatively, it is also possible to reduce polyaniline coatings to a transparent colorless state with aqueous L-ascorbic acid solutions whose pH has been adjusted to 10-11 by adding a base, for example 30% ammonium hydroxide solution. Non-aqueous solutions can also be used. For example, to a solution of ascorbic acid (0.4g) in 20g of degassed methanol was added four drops of the base, l, 8-Diazabicyclo[5.4.0]undec-7-ene (DBU) . This freshly prepared solution was able to reduce polyaniline coatings within a few minutes. The colorless transparent coatings were rinsed with methanol, air dried, and stored under inert atmosphere.

In yet another method, the polyaniline films were dipped into about a 1% to 10% (w/w) solution of phenylhydrazine in methanol or ethanol. Within a few seconds to a few minutes, depending of the film thickness, the films became transparent and colorless. They were rinsed with deoxygenated methanol, then dried and stored under nitrogen. Alternatively, this reduction step was conducted on a spin coater (EC101D model, Headway Research, Inc.). The glass substrate was first rinsed several times with methanol, covered with a 1% to 10% (w/w) solution of phenylhydrazine in methanol for about one minute while still, then spun to remove the reducing solution, and rinsed several times with methanol. The reduced films were dried and stored under nitrogen.

In still another method, the polyaniline coatings on conductive glass substrate were placed in a vacuum chamber which was evacuated to 0.1 to 1 torr. The chamber was then filled with a reducing gas such a sulfur dioxide, or vapors of hydrazine or phenylhydrazine at a pressure of about 1 atmosphere. This cycle was repeated several times until the polyaniline films were completely transparent. This method can also be used to reduce a polyaniline film after the cell fabrication, as described thereafter, and is specially useful for cells having only one filling hole.

Method b: Incorporation in its Oxidized Form Followed by Reduction

In this method, polyaniline coatings were incorporated into the cell in their oxidized form, and thereafter were reduced to a colorless state. Several reagents and procedures were used to reduce these films to a colorless state.

For example, a cell was first constructed by using a conductive substrate coated with an oxidized polyaniline film and another substrate which has only a conductive coating. The two substrates, conductive side facing inwards into the cell, were sealed together at the edges with an epoxy seal material containing glass microbeads as spacers. The cell had two filling holes placed at two diagonally opposed corners, allowing the filling and emptying of the cell cavity with various fluids. The holes can be formed in the seal by removing the epoxy on a length of a few millimeters before assembling and curing, or simply by drilling in the glass substrates. While the glass substrate can be drilled after the assembly of the cell, preferably the substrate is drilled before cell assembly. In this case the substrate was drilled before the deoxgynated aqueous sodium hydrosulfite solution (1% w/w) was injected into the cell with a syringe through one of the filling holes. Within a few minutes, the polyaniline coating inside the cell was reduced to a transparent colorless film. The cell was rinsed by injecting deoxygenated water with a syringe through the filling holes, and dried with a flow of argon or nitrogen flowing from one filling hole to the other. To accelerate the drying process the cell can also be submitted to a final rinse with a water soluble low boiling point organic solvent such as alcohols.

In another procedure, a cell was made with a polyaniline coated substrate and a conducting glass counter electrode, as described above. The cell thickness was about 105 μm. Two holes, approximately 1 mm in diameter, were drilled at two opposite corners of the cell. To reduce the PANI film, the cell was flushed with a deoxygenated aqueous solution of sodium hydrosulfite, rinsed with deoxygenated water, and dried under a flow of argon.

The same procedure can be used with different reducing agents. For example, a solution of phenylhydrazine in methanol or other organic solvents can be used to reduce polyaniline coatings already incorporated into a cell. The reducing solution can easily be introduced into a cell if there is a large aperture or at least two holes to allow the air to escape during the filling, rinsing, and drying procedures. It is sometimes preferable to make cells with only one hole. In that case, vacuum backfilling procedures can be used to inject and remove the reducing and rinsing solutions into the cells, such as described, for example, in previously incorporated U.S. Patent No. 5,140,455.

For example, a cell made with polyaniline coating in its oxidized form (dark blue) and having a single hole for vacuum backfilling, was placed in a vacuum chamber. The chamber was then evacuated to expel the air at a pressure of about 0.1 to 1 torr. A reducing gas consisting of argon saturated with hydrazine vapors was then introduced into the chamber, the final pressure being about 1 atm. The polyaniline coating slowly became transparent around the filing holes. Repeated evacuations of the chamber and purging with the reducing gas were necessary to obtain a fully colorless polyaniline coating. Finally, the chamber and the cell were evacuated and filled with argon several times to remove unreacted hydrazine vapors and the by-products of the reduction process.

Example 12

Preparation and Reduction of Polyaniline Coatings in One Step

Polyaniline thin coatings were obtained in their reduced form directly from a liquid containing polyaniline. When a stoichiometric amount or an excess amount of reducing material such as phenylhydrazine was added to a mixture of 2% w/v of polyaniline in 88% aqueous formic acid, the mixture changed slightly in color. This composition was used to spin cast or dip coat glass substrates to give very light green films. These polyaniline films turned completely transparent after heating at about 100°C in vacuum or in air for a short time. The FT-IR spectra of these films were identical to those reported in the literature for leucoemeraldine base (I. Harada, Y. Furukawa, F. Ueda, Synth . Met. 1989, 21 E303.). The films turned blue in a few days upon exposure to air, indicating reoxidation.

Example 13 EC windows devices with an in situ polyaniline film

A thin film of polyaniline was deposited on a conducting glass substrate by the in si tu polymerization method described above in Example 1. The substrate was a piece (6x3 in.) of TEC 10 glass (available from LOF) . A cell was constructed in the same manner as described in Example 2 with this polyaniline coated substrate and another piece of TEC 10 conducting glass. The cell interface thickness was 105 μm. Two holes (1 mm diameter) were drilled at two opposite corners of the cell. To reduce the PANI film, the cell was flushed with a deoxygenated aqueous solution of sodium hydrosulfite (0.0575M), rinsed again with propylene carbonate (PC) , and dried under a flow of argon.

The cell was then filled with a solution of ethyl viologen diperchlorate (0.31g, 0.075M), in PC (lOmL). When a potential of 1.0 V was applied to the polyaniline coated electrode, the transmission (measured at 550 nm) of the cell changed from 68 %T to 20 %T in about 30 sec. After 30,000 cycles no substantial change in depth of coloration or coloring speed was observed.

Another similar cell was made with TEC 20 glass. The cell had a 300 μm gap which was filled with a solution of tetracyanoquinodimethane (TCNQ, 0.204g, 0.1M), tetrabutylammonium tetrafluoroborate (TBAF, 0.392g. 0.5M) in γ-BL (gamma-butyrlactone) (10 mL) . When a potential of +1.0 V was applied to the polyaniline coated electrode, the transmission (measured at 550 nm) of the cell changed from 49.4%T to 38.8%T in about 25 seconds.

A window device was also made where the rest state (that is with no applied potential) was dark. Such a device may be particularly preferred for use in an automotive sunroof. The polyaniline coatings were not reduced before filling the cell with the electrolyte. Another TEC 20 cell as described above was filled with a solution of butyl ferrocene (0.242g, 0.IM) , lithium triflate (0.78g, 0.5M) in PC (10 mL) . After filling, the cell was green and had a low transmission. When a potential of -1.0 V was applied to the polyaniline coating, the transmission of the cell increased from 10% T to 37% T, measured at 550 nm. When the voltage was removed, the device returned to its initial low transmission state.

Example 14

EC mirror with a polyaniline film

A variable reflectivity mirror (10 x 2.5 in.) was constructed using a conductive glass and a polyaniline coating prepared as in Example 1, by in si tu polymerization on a conducting glass substrate (TEC 20) which was mirrored on the non-conducting side. The cell thickness was about 100 μm. The PANI film was reduced by the procedure set forth in Example 2, method b, employing a deoxygenated aqueous solution of sodium hydrosulfite. The cell was then filled with a solution of ethyl viologen diperchlorate (1.03g, 0.25M) in PC (10 mL) . When a potential of +1.0 V was applied to the polyaniline coated electrode, the reflectivity (measured at 550 nm) of the cell changed from 72 %R to 10 %R in about 6 seconds.

Example 15 Polyaniline Coating from NMP Solutions

A thin film of polyaniline was deposited on a conducting glass substrate from a N-Methylpyrrolidinone (NMP) liquid mixture. The above liquid mixture was made by stirring overnight at room temperature 2g of PANI (Emeraldine Base) in 100 mL of NMP. The dark blue liquid that resulted was then filtered on glass frit. To 2.5 mL of this liquid was added 0.25 mL of a 1% (w/w) solution of FC 430 surfactant in NMP. FC 430 is available from 3M Corporation and was found' to improve significantly the wettability of ITO coated glass with the NMP liquid mixture. The resulting liquid mixture was spread onto half wave ITO glass using a wire wound roll (standard 16" all stainless steel rod, 1/2" diameter, wire size #6, available from Paul N. Gardner Company) and was allowed to dry at room temperature overnight. The film was subsequently placed in an oven at 100°C for one hour to remove most of the solvent.

As described in Example 2, a cell (5 x 2 in.) was made with this polyaniline coated ITO substrate and another piece of half wave ITO conducting glass. The cell thickness was about 105 μm. The polyaniline film was reduced to a colorless state as previously described by filling the cell with a deoxygenated solution (1% w/w) of phenylhydrazine in methanol, rinsed with deoxygenated methanol, then with PC, and dried under a flow of argon. The cell was filled with a solution of ethyl viologen diperchlorate (0.25M) in PC containing 6% (w/w) of 2,4-dihydroxybenzophenone as a UV absorber (available under the tradename Uvinul^® 400 from BASF Corporation). When +1.2 V was applied to the polyaniline coated electrode, the transmission of cell changed from 78 %T to 26 %T (measured at 550 nm) in about 4 sec.

Example 16 EC window devices with PANI.CSA Complex

Two 3x3" inch windows were made using polyaniline: camphorsulfonic acid/polyvinylbutyral (PANI:CSA/PVB) coatings cast onto TEC 20 glass. The counter electrodes were also TEC 20 glass. The cell thicknesses were 105 μm. One film was cast using DMSO as the solvent for PANI. The window was first reduced as in Example 2, method b, and then filled with ethyl viologen diperchlorate (0.4 M), of 10% (w/w) polymethylmethacrylate (PMMA) in PC. This window colored from 65 %T to 19 %T in 8 seconds at 550 nm when +1.0 V was applied. The second film was cast from m- cresol and the window was reduced as before and filled with the same electrolyte. The window colored from 75%T to 19%T in 8 seconds at 550 nm when +1.0V was applied.

Example 17

EC mirrors with polyaniline coating deposited from Aqueous Formic Acid

An interior rearview mirror of the shape for a Range Rover vehicle produced by the Rover Motor Company, England was prepared as follows. A 2% (w/v) liquid composition of PANI was made by stirring 20g of PANI (Emeraldine Base) in 1000 mL commercially available 88% aqueous formic acid (FA) , overnight at room temperature. The mixture was filtered through a 1.5 μm glass filter to remove residues. A 1.3% (w/v) liquid composition of PANI was made by adding 10 mL of FA to 20 mL of the 2% (w/v) PANI liquid composition prepared above. A thin film of polyaniline was spin-cast onto a conducting substrate from this formic acid composition. The substrate was half wave ITO glass (10x2.5 in.) mirrored on the non-conductive side. The polyaniline coating was reduced before the cell assembly, in accordance with the procedure set forth in Example 2, method a. The reduction step was easily conducted with the substrate on the spin coater. The polyaniline coating was first washed with deoxygenated methanol, spun a few seconds to remove excess methanol, then reduced for a few minutes using a 4% (w/w) solution of phenylhydrazine in deoxygenated methanol. The substrate was spun again to remove excess reducing solution, and then washed with deoxygenated methanol. The film was dried overnight under vacuum. As described above, the cell was assembled using this film and another piece of conducting glass. Cell assembly and epoxy curing took place under an inert atmosphere of argon. The cell thickness was about 105 μm. The cell was filled with a solution of ethyl viologen ditriflate (0.768g, 0.IM) and Uvinul^® 400 (1.07g, 0.33M) in PC (15mL) . With +1.0V applied potential, the cell colored from 72.6%R to 20%R (photopic filter) in 3.1 seconds. When zero volts was applied, the cell rapidly bleached to its initial high reflectance state. The rearview mirror continued to show excellent electrochromic response after 61,000 cycles at room temperature, was successfully test driven in an automobile and exhibited heat stability, UV stability and general performance suitable for use in an automobile.

Example 18

Mirror with a Solid Electrolyte

A thin film of polyaniline was spin-cast from 1.5% (w/v) polyaniline liquid mixture in formic acid. The film was reduced on a spin coater as described in Example 2, using 4% (w/w) phenylhydrazine in deoxygenated MeOH. Two cells were assembled and the epoxy cured under an inert atmosphere. The cell thickness was about 105 μm. One of the cells was filled with a monomer composition consisting of ethyl viologen ditriflate (0.768g), Uvinul^® 400 (l.07g), Quick Cure^® B566 resin (2.67g) and PC (17.8g) . Quick Cure^® B566 is the tradename for a UV curable acrylated epoxy urethane resin available from Specialty Coating Systems, Union Carbide. After filling, this composition was placed into the cell cavity and was polymerized to a solid in a UV chamber for 1.5 hours. When +1.0V was applied to the polyaniline coated electrode, the reflectivity (photopic filter) of the cell changed from 68.8 %R to 8.6%R in about 8 seconds. When -0.3 V was applied, the reflectivity changed from 8.7%R to 68.8%R in about 30 seconds. Example 19 Synthesis of a Viologen Salt

Ethylviologen triflate was synthesized. In a dry box (less than 1 ppm 0₂ and H₂0) , ethyl triflate (14 mL, 0.108 mol) was slowly added to a magnetically stirred solution of 4,4' -bipyridine (7.8g, 0.05 mol) in 50 mL of anhydrous acetonitrile. After 2 hours of stirring at room temperature, the flask was taken out of the dry box and the solvents were distilled off. The white solid left was washed with diethyl ether, filtered, and recrystallized in methanol/diethyl ether to give 21.85g of white crystals. The Η NMR in D₂0 was consistent with the proposed structure, as well as the elemental analysis. Calculated for C_]6H₁₈N₂F₆S₂0₆; C, 37.5; H, 3.5; N, 5.5; F, 22.3; S, 12.5. Found: C, 37.47; H, 3.60; N, 5,46; F, 21.71; S, 12.67. The proposed structure of ethyl viologen diperchlorate is represented by the following formula I:

Ethyl viologen diperchlorate may be hazardous to handle because of the known explosive properties of the perchlorate salts. In this regard, ethyl viologen ditriflate is safer to use than the perchlorate salt. Furthermore, this triflate salt is easy to prepare and dissolves more readily in PC than the ethyl viologen diperchlorate salt. does. We also found that the long term stability of electrochromic devices made with polyaniline coatings and a viologen salt improved when ethyl viologen ditriflate was used instead of ethyl viologen diperchlorate.

Example 20

EC Device with a Polyaniline Coating that is Coated and Reduced in One Step

A liquid composition of partially reduced polyaniline was prepared by adding 3 mL of a solution of 10% phenylhydrazine in 88% aqueous formic acid to 5 mL of a 2% (w/v) polyaniline mixture in 88% formic acid. The liquid composition was spin cast on half wave ITO glass, mirrored on the non-conductive side (10x2 in.) and dried at 70°C in a vacuum oven to give a transparent film of leucoemeraldine base.

As described in Example 7, a cell was assembled under argon by covering this substrate with another piece of ITO glass and epoxy adhesive containing 53 μm glass spacers deposited on the edges of the substrate. The cell was cured for 1 hour under inert atmosphere and then vacuum backfilled through a hole left in the epoxy with a solution of ethyl viologen diperchlorate (0.1 M) , lithium perchlorate (1.0 M) , 6% (w/w) Uvinul^® 400 in PC. When +1.0 V was applied to the polyaniline coated electrode, the reflectivity of the cell changed from 65 %R to 11 %R (measured at 550 nm) in about 12 seconds. When -0.3 V was applied, the reflectivity changed from 11 %R in about 16 seconds.

Example 21 EC Device with a polypyrrole (PPY) film

A thin film of polypyrrole was deposited on a conducting glass substrate by the same in situ polymerization method described above for polyaniline. A cold solution of ammonium persulphate in water (50 mL, 0.1 M) was rapidly added to a cold solution of pyrrole in water (50 mL, 0.2 M) and the resulting liquid mixture was poured onto a clean substrate of tin oxide coated glass (TEC 20) . The liquid mixture turned rapidly black and after 3 minutes, the mixture was washed off the surface of the substrate which was rinsed several times with deionized water, then with methanol, and finally air dried. A homogeneous film of polypyrrole was left on the surface of the conducting glass. Its thickness was about 500 A, as measured with a surface profilometer.

As described above, a cell was made with this PPY coated TEC 20 glass and another piece of TEC 20 conducting glass having two filling holes in two opposite corners. The cell thickness was about 105 μm. To insure complete reduction of the PPY film, the cell was filled with a deoxygenated aqueous solution of sodium thiosulfate (1% w/w) , rinsed with deoxygenated water, and dried under a flow of nitrogen. The cell was then filled with a solution of ethyl viologen perchlorate (0.4 M) in GBL (7-butyrolactone) and the filling holes were sealed with an epoxy glue. When a potential of +1.0 V was applied to the polypyrrole coated electrode, the transmission of the window changed from 30%T to 20%T at 660 nm in about 10 seconds, and from 30%T to 10%T at 1300 nm in about 10 seconds.

Example 22 EC Devices with a non conjugated redox polymer film

Polyviologens are colorless in their oxidized state and colored in their reduced form. However, they are not as good electronic conductors as polyaniline in its doped form. The poor electronic conductivity of polyviologens can be increased by adding conductive powders such as W-10 (N. Oyama et al. J. Macromol . Sci . - 72 -

Chem. 1989, A26. 593.). Such polymers can be prepared according to the procedures found in the literature (A. Factor, G. E. Heinsohn, Polymer Letters, 1971, £, 289) .

For example, poly(p-xylyl-4,4' -bipyridyl dibromide) was synthesized by reacting 4,4' -bipyridine (1.56g, 0.01 mol) with a, a' -dibromo-p-xylene (2.63g, 0.01 mol) in dry acetonitrile (50 mL) under argon for 21 hours. The resulting polymer was isolated by filtration, washed with acetonitrile, and dried under vacuum to give 3.74g (89.2% yield) of yellow solid. The UV-Vis spectrum of this polymer in solution in water showed a peak at 262 nm, in accordance with previously published data.

A liquid composition was made by adding 0.25g of the polyviologen dibromide prepared above in 10 mL of 88% aqueous formic acid. This composition was used to spin cast films of polyviologen on half wave ITO coated glass (2.5 x 5 in.) mirrored on the non conductive side. The thickness of these polyviologen films was between 1000 and 1500 A. Variable reflectance rearview mirror cells (2.5 x 5 in.) were then assembled with an ITO coated glass counter electrode, as described above. The gap between the two electrodes was 105 μm.

The cell described above was filled by a vacuum back filling technique with a solution of ferrocene (0.05 M) as the redox material, lithium perchlorate (0.1 M) , and 6% (w/w) Uvinul^® 400 in PC. When -1.0V was applied to the polyviologen coated electrode, the reflectance (photopic filter) changed from 79.7% to 16.7% in about 9 seconds. When +0.3V was applied to the colored polyviologen coated electrode, the reflectance of the cell went back to 79% in about 10 seconds. Another cell as described above was filled with a solution of N,N,N' ,N' -tetramethylphenylenediamine (TMPD) (0.1 M) as the redox material, lithium triflate (0.1 M) , and 6% (w/w) Uvinul^® 400 in GBL. When -1.0V was applied to the polyviologen coated electrode, the reflectance changed from 73.7% to 19.9% in about 25 seconds. When +0.0V was applied to the colored polyviologen coated electrode, the reflectance of the cell went back to 60% in about 3.1 seconds.

Example 23 EC Blue Rest State Mirror with a Polyaniline Coating

A film of polyaniline 220 mm thick, was prepared as given in Example 10, method c. The substrate was half wave ITO glass, about 2x2 in. This substrate was assembled into a cell. Another half wave ITO conductive glass substrate was used as the counter electrode. The cell was assembled by sealing these two substrates at the edges with an epoxy glue containing 210 μm glass beads spacers. One hole was left in the glue to allow the vacuum backfilling of the cell with the electrolyte. The substrates having the same dimensions, they were slightly offset to provide for a place to anchor the electrical leads. The epoxy was thermally cured at 120°C for 1 hour under normal atmosphere. The cell was vacuum backfilled with an electrolyte consisting of 13.5g propylene carbonate, 18.9g of tetramethylene sulfone, 0.23g of ferrocene, 0.03g of lithium perchlorate, 0.09g of lithium tetrafluoroborate, 1.64g of Uvinul 400, and 0.70g of pyridine. The filing hole was plugged with a UV curable glue (Sarbox 500 containing 4% (w/w) Irgacure 184) and the dark blue cell was placed in an oven at 100°C for 4 hours. When 0.6V was applied to the Pani coated electrode, the transmittance (photopic filter) of the blue cell changed from 19%T to 71%T at 550nm. When 0.0V was applied, the reflectivity went back to 19%T.

Example 24 W0₃ and Cobaltocene

A 3x3 in. piece of TEC20 glass substrate was coated with a thin film of W0₃ by a sol-gel method such as disclosed by U.S. Patent 5,252,354 and U.S. Patent No. 4,277,986, the disclosure of both of which is incorporated by reference herein as if fully set forth. A cell was assembled by sealing these two substrates at the edges with an epoxy glue containing 210 μm glass bead spacers. One hole was left in the epoxy glue to allow the filling of the cell. The substrates having the same dimensions, were slightly offset to provide for a place to anchor the electrical leads. This assembly process was carried out under normal atmospheric conditions and the epoxy was thermally cured in an oven under normal atmosphere as well. The cell was then vacuum back filled with an electrolyte consisting of a propylene carbonate (PC) : Sulfolane (TS) mixture (60:40) containing 0.03 M cobaltocene, 0.01 M LiC10₄, and 0.04 M LiBF₄. The device immediately colored after filling. The filling hole was plugged with an epoxy glue. When a potential of +1.3 V was applied to the device (the positive lead being connected to the W0₃ coated electrode) , its transmittance (measured at 550 nm) changed from 5 %T to 55%T in about 190 seconds. The leakage current in the bleached state was 9 mA for an area of 45.5 cm². When the power source was disconnected, its transmission went back from 55 %T to 5 %T in about 100 second.

Other variations and modifications of this invention will be obvious to those skilled in the art.

Claims

WE CLAIM:

1. An electrochromic device comprising two opposed conducting electrodes, at least one of which is transparent, an electrochemically active layer disposed on an opposing face of one of said electrodes and an electrolyte disposed between said electrochemically active layer and an other opposing face of said electrodes, wherein said electrochemically active layer is a mixture of an electrochemically active material and an electrochromically-inert additive selected from the group consisting of reducing agents and oxidizing agents.

2. The electrochromic device according to claim l, further comprising a first substrate disposed on an outwardly facing surface of one of said electrodes and a second substrate disposed on an other outwardly facing surface of said electrodes, wherein at least one of said substrates is transparent.

3. The electrochromic device according to claim l, wherein the electrochromically-inert additive is at least one reducing agent.

4. The electrochromic device according to claim 3, wherein the reducing agent is selected from the group consisting of oxalic acid, ascorbic acid, mercaptans, hydrazines, amines, organo lithium and mixtures thereof.

5. The electrochromic device according to claim l, wherein the electrochromically-inert additive is at least one oxidizing agent.

6. The electrochromic device according to claim 5, wherein the oxidizing agent is selected from the group consisting of persulfates, peroxides, nitrosonium salts and mixtures thereof.

7. The electrochromic device according to claim 1, wherein the electrochemically active material is an electrochemically active polymeric material.

8. The electrochromic device according to claim 7, wherein the electrochemically active polymeric material is selected from the group consisting of polyaniline, a polyaniline derivative and mixtures thereof.

9. The electrochromic device according to claim 1, wherein the electrochemically active material is electrochromic.

10. The electrochromic device according to claim l, further comprising a second electrochemically active layer disposed on the other opposing face of said electrodes.

11. The electrochromic device according to claim 7, wherein the electrochemically active polymeric material is selected from the group consisting of a copolymer, a blend and a composite.

12. The electrochromic device according to claim 1, wherein the at least one transparent electrode is selected from the group consisting of doped indium oxide, doped tin oxide and doped zinc oxide.

13. The electrochromic device according to claim l, wherein said electrolyte contains at least one ionic material.

14. The electrochromic device according to claim 1, wherein the electrolyte contains a viologen salt.

15. The electrochromic device according to claim 2, wherein one of said substrates is reflective.

16. The electrochromic device according to claim 1, wherein one of said electrodes is reflective.

17. The electrochromic device according to claim 1, wherein the electrochemically active layer contains a component selected from the group consisting of UV stabilizers, adhesion promoting agents, heat stabilizers and mixtures thereof.

18. The electrochromic device according to claim 1, wherein the electrolyte contains a component selected from the group consisting of UV stabilizers, heat stabilizers and mixtures thereof.

19. The electrochromic device according to claim 1, wherein the electrolyte is comprised of a mixture of at least two solvents.

20. The electrochromic device according to claim 1, wherein the electrolyte contains a passive visible or infrared dye.

21. The electrochromic device according to claim 1, wherein the electrolyte is comprised of an inert polymeric additive.

22. The electrochromic device according to claim 1, wherein the electrolyte is comprised of a solid polymeric material.

23. The electrochromic device according to claim 1, wherein the electrolyte is comprised of at least one monomer which is polymerizable to a solid after exposure to heat or radiation.

24. The electrochromic device according to claim 2, wherein said device is a vehicular mirror or a vehicular glazing.

25. The electrochromic device according to claim 24, wherein said vehicular mirror is an interior vehicular mirror or an exterior vehicular mirror.

26. The electrochromic device according to claim 25, wherein said interior vehicular mirror is a rearview mirror.

27. The electrochromic device according to claim 24, wherein said vehicular glazing is selected from the group consisting of a vehicular window, a sun roof, sunvisor and a shadeband.

28. An electrochromic device comprising two opposed conducting electrodes, at least one of which is transparent, an electrochemically active layer disposed on an opposing face of one of said electrodes and an electrolyte disposed between said electrochemically active layer and an other opposing face of said electrodes, wherein said electrolyte contains an electrochromically-inert additive selected from the group consisting of reducing agents and oxidizing agents.

29. The electrochromic device according to claim 28, further comprising a first substrate disposed on an outwardly facing surface of one of said electrodes and a second substrate disposed on an other outwardly facing surface of said electrodes, wherein at least one of said substrates is transparent.

30. The electrochromic device according to claim 28, wherein the electrochromically-inert additive is at least one reducing agent.

31. The electrochromic device according to claim 28, wherein the reducing agent is selected from the group consisting of oxalic acid, ascorbic acid, mercaptans, hydrazines, amines, organo lithium and mixtures thereof.

32. The electrochromic device according to claim 28, wherein the electrochromically-inert additive is at least one oxidizing agent.

33. The electrochromic device according to claim 32, wherein the oxidizing agent is selected from the group consisting of persulfates, peroxides, nitrosonium salts and mixtures thereof.

34. The electrochromic device according to claim 28, wherein the electrochemically active layer is comprised of an electrochemically active polymeric material.

35. The electrochromic device according to claim 34, wherein the electrochemically active polymeric material is selected from the group consisting of polyaniline, a polyaniline derivative and mixtures thereof.

36. The electrochromic device according to claim 28, wherein the electrochemically active layer is electrochromic.

37. The electrochromic device according to claim 28, further comprising a second electrochemically active layer disposed on the other opposing face of said electrodes.

38. The electrochromic device according to claim 34, wherein the electrochemically active polymeric material is selected from the group consisting of a copolymer, a blend and a composite.

39. The electrochromic device according to claim 28, wherein the at least one transparent electrode is selected from the group consisting of doped indium oxide, doped tin oxide and doped zinc oxide.

40. The electrochromic device according to claim 28, wherein said electrolyte contains at least one ionic material.

41. The electrochromic device according to claim 28, wherein the electrolyte contains a viologen salt.

42. The electrochromic device according to claim 29, wherein one of said substrates is reflective.

43. The electrochromic device according to claim 28, wherein one of said electrodes is reflective.

44. The electrochromic device according to claim 28, wherein the electrochemically active layer contains a component selected from the group consisting of UV stabilizers, heat stabilizers and mixtures thereof.

45. The electrochromic device according to claim 28, wherein the electrolyte contains a component selected from the group consisting of UV stabilizers, adhesion promoting agents, heat stabilizers and mixtures thereof.

46. The electrochromic device according to claim 28, wherein the electrolyte is comprised of a mixture of at least two solvents.

47. The electrochromic device according to claim 28, wherein the electrolyte contains a passive visible or infrared dye.

48. The electrochromic device according to claim 28, wherein the electrolyte is comprised of an inert polymeric additive.

49. The electrochromic device according to claim 28, wherein the electrolyte is comprised of a solid polymeric material.

50. The electrochromic device according to claim 28, wherein the electrolyte is comprised of at least one monomer which is polymerizable to a solid after exposure to heat or radiation.

51. The electrochromic device according to claim 29, wherein said device is a vehicular mirror or a vehicular glazing.

52. The electrochromic device according to claim 51, wherein said vehicular mirror is an interior vehicular mirror or an exterior vehicular mirror.

53. The electrochromic device according to claim 52, wherein said interior vehicular mirror is a rearview mirror.

54. The electrochromic device according to claim 51, wherein said vehicular glazing is selected from the group consisting of a vehicular window, a sun roof, sunvisor and a shadeband.

55. A process for preparing an electrochemically active layer on a substrate comprising the steps of: (a) forming a liquid mixture of an electrochemically active material and an electrochromically-inert additive selected from the group consisting of reducing agents and oxidizing agents;

(b) contacting the liquid mixture to the substrate; and

(c) optionally exposing said contacted substrate to a temperature for a sufficient length of time for the electrochromically-inert additive to reduce or oxidize the electrochemically active material.

56. The process according to claim 55, wherein the electrochemically active material is an electrochemically active polymeric material.

57. The process according to claim 56, wherein the electrochemically active polymeric material is selected from the group consisting of polyaniline, a polyaniline derivative and mixtures thereof.

58. The process according to claim 55, wherein the substrate is a conductive coated substrate.

59. The process according to claim 58, wherein the conductive coating on said substrate is selected from the group consisting of doped indium oxide, doped tin oxide and doped zinc oxide.

60. The process according to claim 55, wherein the electrochromically-inert additive is at least one reducing agent.

61. The process according to claim 60, wherein the reducing agent is selected from the group consisting of oxalic acid, ascorbic acid, mercaptans, hydrazines, amines, organo lithium and mixtures thereof.

62. The process according to claim 55, wherein the electrochromically-inert additive is at least one oxidizing agent.

63. The process according to claim 62, wherein the oxidizing agent is selected from the group consisting of persulfates, peroxides, nitrosonium salts and mixtures thereof .

64. A process for preparing an electrochromic device having two opposed electrodes, at least one of which is transparent, an electrochemically active layer disposed on an opposing face of one of said electrodes and an electrolyte disposed between said electrochemically active layer and an other opposing face of said electrodes, said process comprising the steps of:

(a) forming said electrochemically active layer on said opposing face of one of said electrodes by contacting said opposing face with a liquid mixture of an electrochemically active material and an electrochromically-inert additive selected from the group consisting of reducing agents and oxidizing agents;

(d) filling said cell with an electrolyte.

65. The process according to claim 64, wherein the electrochemically active material is an electrochemically active polymeric material.

66. The process according to claim 65, wherein the electrochemically active polymeric material is selected from the group consisting of polyaniline, a polyaniline derivative and mixtures thereof.

67. The process according to claim 64, wherein the conductive coating on said substrate is selected from the group consisting of doped indium oxide, doped tin oxide and doped zinc oxide.

68. The process according to claim 64, wherein the electrochromically-inert additive is at least one reducing agent.

69. The process according to claim 68, wherein the reducing agent is selected from the group consisting of oxalic acid, ascorbic acid, mercaptans, hydrazines, amines, organo lithium and mixtures thereof.

70. The process according to claim 64, wherein the electrochromically-inert additive is at least one oxidizing agent.

71. The process according to claim 70, wherein the oxidizing agent is selected from the group consisting of persulfates, peroxides, nitrosonium salts and mixtures thereof.

72. The process according to claim 64, wherein a first substrate is disposed on a non-opposing surface of one of said electrodes and a second substrate is disposed on an other non-opposing surface of said electrodes, wherein at least one of said substrates is transparent.

73. The process according to claim 72, wherein one of said substrates is reflective.

74. The process according to claim 64, wherein one of said electrodes is reflective.

75. The process according to claim 64, wherein the electrochemically active material is an inorganic material .

76. The process according to claim 64, further comprising the step of forming a second electrochemically active layer on the other opposing face of said electrodes.

77. A process for preparing an electrochromic device having two opposed electrodes, at least one of which is transparent, an electrochemically active layer disposed on an opposing face of one of said electrodes and an electrolyte disposed between said electrochemically active layer and an other opposing face of said electrodes, said process comprising the steps of:

(b) assembling said electrodes in a spaced-apart opposing relationship with said electrochemically active layer facing said other opposing face of said electrodes to form a cell;

(c) filling said cell with an electrolyte containing an electrochromically-inert additive selected from the group consisting of reducing agents and oxidizing agents; and

(d) optionally exposing said filled cell to a temperature for a sufficient length of time for the electrochromically-inert additive to reduce or oxidize said electrochemically active material.

78. The process according to claim 77, wherein the electrochemically active material is an electrochemically active polymeric material.

79. The process according to claim 78, wherein the electrochemically active polymeric material is selected from the group consisting of polyaniline, a polyaniline derivative and mixtures thereof.

80. The process according to claim 77, wherein the at least one transparent conductive electrode is selected from the group consisting of doped indium oxide, doped tin oxide and doped zinc oxide.

81. The process according to claim 77, wherein the electrochromically-inert additive is at least one reducing agent.

82. The process according to claim 81, wherein the reducing agent is selected from the group consisting of oxalic acid, ascorbic acid, mercaptans, hydrazines, amines, organo lithium and mixtures thereof.

83. The process according to claim 77, wherein the electrochromically-inert additive is at least one oxidizing agent.

84. The process according to claim 83, wherein the oxidizing agent is selected from the group consisting of persulfates, peroxides, nitrosonium salts and mixtures thereof.

85. The process according to claim 77, wherein a first substrate is disposed on a non-opposing surface of one of said electrodes and a second substrate is disposed on an other non-opposing surface of said electrodes.

86. The process according to claim 85, wherein one of said substrates is reflective.

87. The process according to claim 77, wherein one of said electrodes is reflective.

88. The process according to claim 77, wherein the electrochemically active material is an inorganic material.

89. The process according to claim 77, further comprising the step of forming a second electrochemically active layer on the other opposing face of said electrodes.

90. An electrochromic device comprising two opposed conducting electrodes, at least one of which is transparent, an electrochemically active layer comprised of a polyaniline or a polyaniline derivative disposed on an opposing face of one of said electrodes and an electrolyte disposed between said electrochemically active layer and an other opposing face of said electrodes, wherein said electrochemically active layer is a mixture of polyaniline or the polyaniline derivative and an electrochromically-inert reducing agent.

91. The electrochromic device according to claim 90, wherein the reducing agent is selected from the group consisting of oxalic acid, ascorbic acid, mercaptans, amines, organo lithium and mixtures thereof.

92. The electrochromic device according to claim 91 wherein the reducing agent is ascorbic acid.

93. An electrochromic device comprising two opposed conducting electrodes, at least one of which is transparent, an electrochemically active layer comprised of a polyaniline or a polyaniline derivative disposed on an opposing face of one of said electrodes and an electrolyte disposed between said electrochemically active layer and an other opposing face of said electrodes, wherein said electrolyte contains an electrochromically-inert reducing agent.

94. The electrochromic device according to claim 93, wherein the reducing agent is selected from the group consisting of oxalic acid, ascorbic acid, mercaptans, hydrazines, amines, butyl lithium and mixtures thereof.

95. The electrochromic device according to claim 94, wherein the reducing agent is ascorbic acid.

96. An electrochromic device comprising a conducting electrode opposing a counter conducting electrode with an electrochemically active polymeric material layer disposed on an opposing surface of one of said electrodes and an electrolyte containing at least one redox active material contactingly disposed between said electrochemically active polymeric material layer and an other opposing surface of one of said electrodes, wherein at least one of said electrodes is transparent.

97. The electrochromic device according to claim 96, further comprising a first substrate disposed on an outwardly facing surface of one of said electrodes and a second substrate disposed on an other outwardly facing surface of said electrodes, wherein at least one of said substrates is transparent.

98. The electrochromic device according to claim 96, wherein at least one of the electrochemically active polymeric layer or the redox active material is electrochromic.

99. The electrochromic device according to claim 96, wherein said electrolyte contains at least one ionic material.

100. The electrochromic device according to claim 96, wherein the electrolyte contains a mixture of salts having different cations or anions.

101. The electrochromic device according to claim 96, wherein the redox active material is a viologen salt.

102. The electrochromic device according to claim 96, wherein the electrochemically active polymeric layer contains an additive selected from group consisting of UV stabilizers, adhesion promoting agents,heat stabilizers and mixtures thereof.

103. The electrochromic device according to claim 96, wherein the electrolyte contains an additive selected from group consisting of UV stabilizers, heat stabilizers and mixtures thereof.

104. The electrochromic device according to claim 96, wherein the electrolyte is comprised of a mixture of at least two solvents.

105. The electrochromic device according to claim 96, wherein the electrolyte contains a passive visible or infrared dye.

106. The electrochromic device according to claim 961, wherein the electrolyte is comprised of an inert polymeric additive.

107. The electrochromic device according to claim 96, wherein the electrolyte is comprised of a solid polymeric material.

108. The electrochromic device according to claim 96, wherein the electrolyte is comprised of at least one monomer which is polymerizable to a solid after exposure to heat or radiation.

109. The electrochromic device according to claim 96, wherein the electrochemically active polymeric layer is electrochromic.

110. The electrochromic device according to claim 96, wherein the electrochemically active polymeric layer is selected from the group consisting of a copolymer, a blend and a composite, wherein said copolymer, said blend or said composite contains at least one electrochemically active compound.

ill. The electrochromic device according to claim 96, wherein the electrochemically active polymeric layer is electronically conductive in at least its oxidized or reduced state.

112. The electrochromic device according to claim 96, wherein the electrochemically active polymeric layer is selected from the group consisting of polyaniline, a polyaniline derivative and mixtures thereof.

113. The electrochromic device according to claim 96, wherein the at least one transparent electrode is comprised of a group selected from doped indium oxide, doped tin oxide and doped zinc oxide.

114. The electrochromic device according to claim 97, wherein the at least one transparent substrate is selected from group of specific colored substrates, photochromic substrates, infrared absorbing substrates, reflecting substrates, ultraviolet absorbing substrates and mixtures thereof.

115. The electrochromic device according to claim 97, wherein the at least one transparent substrate is further comprised of a coating on the outward facing surface, said coating selected from the group consisting of an antireflection coating, an antifogging coating, an antiabrasion coating, an ultraviolet quenching coating and mixtures thereof.

116. The electrochromic device according to claim 97, wherein at least one of the substrates is further comprised of a coating, tape or lamination selected from the group consisting of an antilacerative, an antiscatter, a colored, a ultraviolet blocking, an IR blocking coating, tape or lamination and mixtures thereof.

117. The electrochromic device according to claim 97, wherein one of said substrates is reflective.

118. The electrochromic device according to claim 97, further comprising a reflective layer disposed on an inward or outward facing surface of one of said substrates.

119. The electrochromic device according to claim 96, wherein one of said electrodes is a reflective material.

120. The electrochromic device according to claim 97, wherein said device is a vehicular mirror or a vehicular glazing.

121. The electrochromic device according to claim 120, wherein said vehicular mirror is an interior vehicular mirror or an exterior vehicular mirror.

122. The electrochromic device according to claim 121, wherein said interior vehicular mirror is a rearview mirror.

123. The electrochromic device according to claim 120, wherein said vehicular glazing is selected from the group consisting of a vehicular window, a sun roof, sunvisor and a shadeband.

12 . An electrochromic device comprising a conducting electrode opposing a counter conducting electrode with an electrochemically active polymeric layer of a polyaniline or a polyaniline derivative disposed on an opposing surface of one of said electrodes and an electrolyte containing a viologen salt disposed in a contacting relationship between said electrochemically active layer and an other opposing surface of one of said electrodes, wherein at least one of said electrodes is transparent.

125. The electrochromic device according to claim 124, further comprising a first substrate disposed on an outwardly facing surface of one of said electrodes and a second substrate disposed on an other outwardly facing surface of said electrodes, wherein at least one of said substrates is transparent.

126. The electrochromic device according to claim 125, wherein one of said substrates is reflective.

127. The electrochromic device according to claim 125, further comprising a reflective layer disposed on an inward or outward facing surface of one of said substrates.

128. The electrochromic device according to claim 124, wherein one of said electrodes is reflective.

129. The electrochromic device according to claim 124, wherein the electrolyte contains at least one UV stabilizer/absorber.

130. An electrochromic device comprising a conducting electrode opposing a counter conducting electrode with an electrochemically active polymeric material layer disposed on an opposing surface of one of said electrodes and an electrolyte containing at least one redox active material contactingly disposed between said electrochemically active polymeric material layer and an other opposing surface of one of said electrodes, wherein at least one of said electrodes is transparent and (i) said electrochemically active polymeric material is a negative electrochemically active polymeric material having a redox potential greater than a redox potential of said redox active material or (ii) said electrochemically active polymeric material is a positive electrochemically active polymeric material having a redox potential less than a redox potential of said redox active material.

131. An electrochromic device according to claim 130, further comprising a first substrate disposed on an outwardly facing surface of one of said electrodes and a second substrate disposed on an other outwardly facing surface of said electrodes, wherein at least one of said substrates is transparent.

132. An electrochromic device according to claim 131, wherein said electrochemically active polymeric material is selected from the group consisting of polyaniline, a polyaniline derivative and mixtures thereof.

133. An electrochromic device according to claim 132, wherein the redox active material is a metallocene or its derivative.

134. An electrochromic device according to claim 133, wherein the metallocene is ferrocene.

135. An electrochromic device comprising a conducting electrode opposing a counter conducting electrode with an electrochemically active inorganic metal oxide material layer disposed on an opposing surface of one of said electrodes and an electrolyte containing at least one redox active material contactingly disposed between said electrochemically active inorganic metal oxide material layer and an other opposing surface of one of said electrodes, wherein at least one of said electrodes is transparent and (i) said electrochemically active inorganic metal oxide material is a negative electrochemically active inorganic metal oxide material having a redox potential greater than a redox potential of said redox active material or

(ii) said electrochemically active^' inorganic metal oxide material is a positive electrochemically active inorganic metal oxide material having a redox potential less than a redox potential of said redox active material.

136. An electrochromic device according to claim 135, further comprising a first substrate disposed on an outwardly facing surface of one of said electrodes and a second substrate disposed on an other outwardly facing surface of said electrodes, wherein at least one of said substrates is transparent.

137. An electrochromic device according to claim 136, wherein said inorganic metal oxide is selected from the group consisting of W0₃, V₂0j, Mo0₃, Nb₂0₅, Ti0₂, CuO, Ni₂0₃, lr₂0₃, Cr₂0₃, Co₂0₃, Mn0₃ and mixtures thereof.

138. An electrochromic device according to claim 137, wherein said redox active material is a metallocene or its derivative.

139. An electrochromic device according to claim 138, wherein said metallocene is cobaltocene.