Multilayer low current electro-optical assembly.

Abstract

The electro-optic assembly includes a first substrate and a second substrate disposed in a substantially parallel, spaced apart relationship to the first substrate. A first conductive layer is disposed on the first substrate and a second conductive layer is disposed on the second substrate. A cathodic electro-optic film is in contact with the second conductive layer and includes a cathodic species. An anodic electro-optic film is in contact with the first conductive layer. The anodic electro-optic film includes a plurality of anodic species mixed in a molar ratio configured to generally maintain the a* and b* values ​​of the electro-optic assembly, both of which remain between a high end transmissive state and a fully darkened state caused by an applied voltage range of -8 to 8. An electrolyte medium is disposed between the cathodic electro-optic film and the anodic electro-optic film.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to electro-optic assemblies, and more particularly to electro-optic assemblies having variable transmission that maintain a stable neutral color during and after a change in transmission. Summary of the Invention

[0002] According to one aspect of the disclosure, an electro-optic assembly includes a first substrate having a first surface and a second surface disposed on opposing sides thereof, and a second substrate having a third surface and a fourth surface disposed on opposing sides thereof. The second substrate is disposed in a substantially parallel spaced apart relationship with the first substrate, such that the second surface and the third surface face each other. A first conductive layer is disposed on the second surface, and a second conductive layer is disposed on the third surface. A cathodic electro-optic film is in contact with the second conductive layer and includes a cathodic species. An anodic electro-optic film is in contact with the first conductive layer. The anodic electro-optic film includes a plurality of anodic species mixed in a molar ratio configured to generally maintain the a* and b* values ​​of the electro-optic assembly, both of which remain between a high end transmission state and a fully darkened state caused by an applied voltage range of -8 to 8. An electrolyte medium is disposed between the cathodic electro-optic film and the anodic electro-optic film.

[0003] According to another aspect of the disclosure, an electro-optic assembly includes a first substrate having a first surface and a second surface disposed on opposing sides thereof, and a second substrate having a third surface and a fourth surface disposed on opposing sides thereof. The second substrate is disposed in a substantially parallel spaced apart relationship with the first substrate, such that the second surface and the third surface face each other. A first conductive layer is disposed on the second surface, and a second conductive layer is disposed on the third surface. A cathodic electro-optic film is in contact with the second conductive layer and includes a cathodic species. An anodic electro-optic film is in contact with the first conductive layer. The anodic electro-optic film includes a plurality of anodic species mixed in a molar ratio configured to generally maintain the a* and b* values ​​of the electro-optic assembly, both of which remain between -8 and 8 between a high end transmission state and a fully darkened state caused by an applied voltage range. The plurality of anode species includes a first anode species and a second anode species, the first anode species comprising a molar percentage of the sum of the first anode species and the second anode species between 80% and 60%. An electrolyte medium is disposed between the cathodic electro-optic film and the anodic electro-optic film.

[0004] These and other features, advantages, and objectives of the present disclosure will be further understood and appreciated by those skilled in the art with reference to the following specification, claims, and accompanying drawings.

[0005] In the drawings: [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a cross-sectional view of an electro-optic assembly according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram of components of a cathodic electro-optic film in an electro-optic assembly according to an embodiment of the present disclosure. [Diagram 3] FIG. 3 is an absorption spectrum of a cathode film in the dark according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a schematic diagram of the components of an anodic electro-optic film in an electro-optic assembly according to an embodiment of the present disclosure. [Diagram 5]FIG. 5 is a schematic diagram of a first variation (unsubstituted) of anode species that may be selected for an anodic electro-optic film according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is an absorption spectrum of an anodic electro-optic film containing a single anodic species selected from a first variety of anodic species. [Figure 7] FIG. 7 is a darkened absorption spectrum of an electro-optic assembly including a cathodic electro-optic film and an anodic electro-optic film including an anodic species selected from a first variety of anodic species. [Figure 8] FIG. 8 is a schematic diagram of a second variation of anodic species (substituted at the 2,7 or 2,8 positions) that may be selected for an anodic electro-optic film according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is an absorption spectrum of an anodic electro-optic film in the dark containing a single anodic species selected from the second variety of anodic species. [Figure 10] FIG. 10 is an absorption spectrum of an electro-optic assembly in the dark including a cathodic electro-optic film and an anodic electro-optic film including a single anodic species selected from the second variety of anodic species. [Figure 11] FIG. 11 is a table providing specific example formulations of anodic and cathodic electro-optic films prior to deposition according to an embodiment of the present disclosure. [Figure 12] FIG. 12 is an absorption spectrum of an electro-optic assembly in a darkened state having an anodic electro-optic film having a first variant of an anodic species at a molar ratio of 60% and a second variant of an anodic species at a molar ratio of 40% according to an embodiment of the present disclosure. [Figure 13] FIG. 13 is an absorption spectrum of an electro-optic assembly having an anodic electro-optic film with a first variant of an anodic species at a molar ratio of 80% and a second variant of an anodic species at a molar ratio of 20% according to an embodiment of the present disclosure. [Figure 14] FIG. 14 is a table summarizing performance metrics of electro-optic assemblies compared to electro-optic devices having only one anode type, according to an embodiment of the present disclosure. [Figure 15]FIG. 15 is a color shift graph for transitioning from clear to fully dark for an electro-optic assembly according to an embodiment of the present disclosure. [Figure 16] FIG. 16 is a color shift graph of an electro-optic assembly under varying applied voltages, according to an embodiment of the present disclosure. [Figure 17] FIG. 17 is a color shift graph of an electro-optic assembly over varying transmission ranges according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present embodiment illustrated resides primarily in a combination of method steps and equipment components for an electro-optical assembly having variable transmission that maintains a stable neutral color during and after a change in transmission. As a result, equipment components and method steps are presented and, where appropriate, only those specific details relevant to an understanding of the embodiments of the present disclosure are shown by conventional symbols in the drawings, so as not to obscure the disclosure with details that will be readily apparent to those skilled in the art having the benefit of the descriptions herein. Moreover, like numerals in the description and drawings represent like elements.

[0008] For purposes of description herein, the terms "upper", "lower", "right", "left", "rear", "front", "vertical", "horizontal", and derivatives thereof, shall refer to the disclosure as oriented in FIG. 1. Unless otherwise specified, the term "front" shall refer to the surface of the device closer to the intended observer of the device, and the term "rear" shall refer to the surface of the device further from the intended observer of the device. It is understood, however, that the present disclosure may contemplate various alternative orientations, unless expressly specified to the contrary. It is also understood that the specific devices and processes illustrated in the accompanying drawings and described in the following specification are merely exemplary embodiments of the inventive concepts as defined in the appended claims. Thus, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not considered limiting, unless the claims expressly state otherwise.

[0009] The terms "comprise," "comprises," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, whereby a process, method, article, or facility that includes a list of elements may include not only those elements, but may also include other elements not expressly listed or that are inherent to such process, method, article, or facility. An element preceded by "comprises..." does not, without further constraints, exclude the presence of additional identical elements in the process, method, article, or facility that includes the element.

[0010] The present disclosure generally relates to an electro-optical system including a multi-layer configuration having a low current requirement to hold a particular transmission state within a variety of different transmission states. The different transmission states are achieved by applying a particular external potential across a first conductive layer and a second conductive layer, which results in an absorbance change in the anodic and cathodic electro-optic films. The different transmission states remain neutral colors during the transition between the different transmission states of the device. In addition, the different transmission states remain stable over long periods of time when the electro-optical assembly remains in an open circuit state. The electro-optical system includes at least two anodic species.

[0011] Referring initially to FIG. 1, reference numeral 10 generally designates an electro-optic assembly (e.g., electrochromic). In various embodiments, the electro-optic assembly 10 may be implemented in windows, displays, sunroofs, optical filters, eyeglasses, mirrors, and various other applications that may benefit from varying the transmission of light through one or more substrates. The embodiments shown in the figures are illustrated with a generally flat substrate, however, it is understood that the present disclosure is not limited to flat substrates. The substrate may be flat, curved, bent, or a combination of these shapes without departing from the spirit of the present disclosure. The electro-optic assembly 10 includes a first substrate 12 defining a first surface 14, a second surface 16, and a first peripheral edge 18. The first substrate 12 may be substantially transparent. The electro-optic assembly 10 also includes a second substrate 20 defining a third surface 22, a fourth surface 24, and a second peripheral edge 26. The second substrate 20 may also be substantially transparent. First substrate 12 and second substrate 20 are disposed in a parallel, spaced apart relationship with second surface 16 and third surface 22 facing each other so as to define a cavity 28 therebetween. First substrate 12 and second substrate 20 may be formed of glass (e.g., soda-lime glass or borosilicate glass), plastic, ceramic, metal, combinations thereof, and / or the like.

[0012] The electrolyte medium 30 at least partially fills the cavity 28. The electrolyte medium 30 includes ionically conductive materials such as electrolytes, other non-gelling electrolytes, and solvents containing electrolyte gels or solids. The electrolyte may include ionic salts for ionic conductivity and may have cations of tetramethylammonium, tetraethylammonium, tetrabutylammonium, F - , Cl - , Br - , I - , BF4 - , PF6 - , SbF6 - , AsF6 - , ClO4 - , SO3CF3 -, N(CF3SO2)2 - , C(CF3SO2)3 - , N(SO2C2F5)2 - , Al(OC(CF3)3)4 - , BAr4 - or a mixture of these anions, where Ar is an aryl group or a fluorinated aryl group. In some embodiments, the anion is PF6 - and / or SO3CF3 - As a non-limiting example, the anion may be tetraethylammonium hexafluorophosphate and / or other ion-conducting substances such as polymer binders, solvents, plasticizers, and UV stabilizers. The first conductive layer 32 may be disposed on the second surface 16 of the first substrate 12, and the second conductive layer 34 may be disposed on the third surface 22 of the second substrate 20. In other words, the first conductive layer 32 and the second conductive layer 34 may be located on the inner surfaces of the first substrate 12 and the second substrate 20 facing the cavity 28. The first conductive layer 32 and the second conductive layer 34 may be formed of a conductive transparent material. These include, but are not limited to, conductive oxides such as transparent metal oxides (e.g., indium tin oxide ("ITO"), tin oxide ("SnO2"), zinc oxide ("ZnO"), indium zinc oxide ("IZO")), intermetallic-metal-intermetallic (IMI) structures, carbon (graphene and / or graphite), and / or conductive metal meshes (e.g., nanowires).

[0013] The electrical bus 36 may include segments that run at least partially along the peripheral edge of the cavity 28 on the first conductive layer 32 and the second conductive layer 34. For example, the electrical bus 36 may include a conductive adhesive, tape, and / or the like, which may include a higher electrical conductivity than one or both of the first conductive layer 32 and the second conductive layer 34. The electrical bus 36 may include segments disposed on an interior surface (e.g., a surface facing toward the cavity 28) of the first conductive layer 32 and / or the second conductive layer 34, or the electrical bus 36 may include segments disposed on an exterior surface (e.g., a surface facing away from the cavity 28) of the first conductive layer 32 and / or the second conductive layer 34. In some cases, the electrical bus 36 may include a segment that traverses the entire outer perimeter of the cavity 28 on the first conductive layer 32 and a segment that traverses the entire outer perimeter of the cavity 28 on the second conductive layer 34. In some cases, the segments of the electrical bus 36 may be localized to one or more alternative locations. The first peripheral edge 18 of the first substrate 12 and the second peripheral edge 26 of the second substrate 20 may not be aligned correctly, such that the first substrate 12 defines a first overhanging portion 38 that extends past the second peripheral edge 26 and the second substrate 20 defines a second overhanging portion 40 that extends past the first peripheral edge 18. In some embodiments, the first conductive layer 32 may extend along a portion of the first overhanging portion 38 and the segments of the electrical bus 36 may be at least partially located on the first conductive layer 32 above the first overhanging portion 38. In some embodiments, the second conductive layer 34 may extend along a portion of the second overhanging portion 40 and the segments of the electrical bus 36 may be at least partially located on the second conductive layer 34 above the second overhanging portion 40. However, it will be appreciated that in some embodiments, the substrates 12, 20 may be aligned (ie, not have overhanging portions 38, 40).

[0014] The seal 42 may include a substantially continuous line outlining the periphery of the cavity 28 to hold the electrolyte medium 30, the anode electro-optic film 44, and the cathode electro-optic film 46 in an inward direction between the first substrate 12 and the second substrate 20. The seal 42 may have a sealing medium such as epoxy, acrylic, and / or the like. The seal 42 may be located inward from the electrical bus 36. In other words, the first conductive layer 32 and / or the second conductive layer 34 may include an outer peripheral edge that extends past the seal 42. For example, the seal 42 may be located inward from both the first overhanging portion 38 and the second overhanging portion 40 and spaced inward from the electrical bus 36. However, it will be appreciated that in other arrangements, the seal 42 may substantially cover and / or be aligned with the electrical bus 36, or may be located elsewhere.

[0015] 1, the electro-optic assembly 10 further includes an anode electro-optic film 44 and a cathode electro-optic film 46. The anode electro-optic film 44 is located on (e.g., in contact with) the inner surface of the first conductive layer 32, thereby interacting with the electrolyte medium 30. The cathode electro-optic film 46 is located on (e.g., in contact with) the inner surface of the second conductive layer 34, thereby interacting with the electrolyte medium 30 as well. In other words, the electrolyte medium 30 may be sandwiched between both the anode electro-optic film 44 and the cathode electro-optic film 46. The anode electro-optic film 44 and the cathode electro-optic film 46 may be deposited on the first conductive layer 32 and the second conductive layer 34 via any number of processes. For example, the anode electro-optic film 44 and the cathode electro-optic film 46 may be formed by depositing on the conductive layer 32, 34 material that forms an electro-optic film (e.g., a memory electro-optic film) with a coating solvent, a leveling agent, and / or the like. The anodic electro-optic film 44 and the cathodic electro-optic film 46 are configured to provide a substantially intermediate color optical switching between the varying transmission states and a completely dark state. For example, the anodic electro-optic film 44 may include a plurality of anodic species (i.e., moieties that are oxidized), including at least a first anodic species and a second anodic species. Generally, the embodiments disclosed herein include at least two anodic and cathodic species, for a total of at least three species. In various embodiments, the anodic and cathodic species have absorption spectra that change when electrically activated, such that the color of the electro-optic assembly 10, when assembled, remains an intermediate and stable color throughout the varying transmission states.

[0016] The changing transmission is due to one electron per cathodic species reduction or one electron per anodic species oxidation, which is accompanied by a change from a high transmission state (e.g., a clear state in the range of about 40-95%) or from a relatively clear and colorless state to a low transmission state or a completely darkened state (e.g., a darkened state in the range of about 0.001%-30% or 0.001%-10%). Generally, the total number of anodic species oxidized should be less than or equal to the total number of cathodic species. To maintain a preselected perceived color during the darkening and clearing transitions, all of the anodic species should have similar redox potentials to each other, and all of the cathodic species should have similar redox potentials to each other. The redox potentials of each anodic species may be within 200 mV of each other, e.g., 150 mV, 100 mV, or 50 mV, to maintain intermediate color stability between the transmission states.

[0017] In various embodiments, the anodic electro-optic film 44 may comprise a polymer matrix film, with the anodic species bonded to the polymer matrix film and surfaces trapped therein. In various embodiments, the cathodic electro-optic film 46 may comprise a polymer matrix film, with the cathodic species bonded to the polymer matrix film and surfaces trapped therein. Since many optional cathodic species contain viologens densely concentrated in the polymer matrix film, difficulties arise in obtaining neutral coloration as a result of viologen dimerization, often switching the red color (a* positive) of the cathodic electro-optic film 46 to electrochemical reduction. Neutral colors are achieved in part by mixing ratios of two or more of the anodic species. Neutrality is also achieved by maintaining a molar excess of the cathodic species over the anodic species. The species chosen and the ratio between the species correlate with the degree of neutrality throughout the change in transmission. The anodic and cathodic species may be mixed in a solvent prior to deposition. Thus, the anode electro-optic film 44 may be a homogeneous layer having a uniform concentration of two or more anode species, and the cathode electro-optic film 46 may be a homogeneous layer having a uniform concentration of cathode species. Of course, in some embodiments, two or more electro-optic assemblies 10 may be stacked, such that the two or more electro-optic assemblies 10 in combination include at least three species or at least four species, including at least two anode species and a cathode species (not shown).

[0018] In considering color, it is useful to refer to the Commission Internationale de l'Eclairage's (CIE) 1976 CIELAB Chromaticity Diagram (commonly referred to as the L*a*b* chart), as generally shown by the a* and b* values in FIGS. 15 - 17. In the L*a*b* chart, L* defines lightness, a* indicates a red / green value, and b* indicates a yellow / blue value. The electro - optical assembly 10 has an absorption spectrum at each specific voltage that may be converted to three - digit specifications, its L*a*b* values. As discussed herein, when the electro - optical assembly 10 changes from the application of an applied voltage to a completely dark state, the term "intermediate color" may be defined as an a* value maintained between - 8 and 8, for example, between - 6 and 6, - 6 < a* < 6, between - 5 and 5, - 5 < a* < 5, between - 4 and 4, or - 4 < a* < 4 or less, and a b* value maintained between - 8 and 8, for example, between - 6 and 6, - 6 < b* < 6, between - 5 and 5, - 5 < b* < 5, between - 4 and 4, or - 4 < b* < 4 or less. These values may also be maintained over an applied voltage range (e.g., from a low transmission state to a high transmission state, from a high transmission state to a low transmission state, and / or an intermediate transmission state). Further, it is important for the electro - optical assembly 10 to exhibit color stability. Color stability is the change in color as a function of time. In other words, color stability may be defined as a specific range of the total color shift of the a* and b* values as the electro - optical assembly 10 changes from a completely clear high - transmission state, including intermediate states, to a completely dark state, or vice versa (e.g., from a low transmission state to a high transmission state). Thus, color stability may be defined as the total color shift of the a* values between - 10 and 10, for example, between - 8 and 8 or - 8 < a* < 8, and the total color shift of the b* values between - 10 and 10, for example, between - 8 and 8 or - 8 < b* < 8, from the application of an applied voltage or an applied voltage range.

[0019] Once the transparent state is obtained, the electro-optic assembly 10 has a memory in which the color remains neutral and stable for an extended period of time when the electro-optic assembly 10 is left in an open circuit state or until the voltage is reversed or the system is shorted. In operation, the injection of electrons in the cathode (reduction) and the removal of electrons in the anode (oxidation) are localized to the individual films (e.g., the anode electro-optic film 44 and the cathode electro-optic film 46) and the opposite charges cannot recombine due to the separation of the cathode and anode into two separate layers by the electrolyte medium 30. The change in charge of each layer or film from the injection and removal of electrons (cathode and anode, respectively) is counterbalanced by the movement of electrolyte counterions between the two layers or films. Testing has shown that the electro-optic assembly 10 can remain in a preselected transparent state with neutral coloration for several weeks. The applied voltage range may be associated with a low extraction current range resulting from the applied voltage or open circuit potential. Thus, the electro-optic assembly 10 may have a low extraction current range requirement. The low current range may be defined as less than 1 microampere per square centimeter.

[0020] 1-8, various material examples are provided for the electrolyte medium 30, the anode electro-optic film 44, and the cathode electro-optic film 46. In the examples provided, the anode electro-optic film 44 includes a plurality of anode species including a first anode species and a second anode species, and the cathode electro-optic film 46 includes at least one cathode species. However, it will be understood that the material examples are exemplary in nature and that a wide variety of alternative materials may be substituted and synthesized to provide similar neutral color and stability to those examples provided below.

[0021] 1-8, examples of materials for the electrolyte medium 30 are provided according to various embodiments. The electrolyte medium 30 may be formed as an electrolyte membrane and / or gel including a first electrolyte salt 48, an electrolyte crosslinker 50 (i.e., a first crosslinker), an electrolyte polymer 52, and an electrolyte solvent 54. In some embodiments, the first electrolyte salt 48 may include cations of tetramethylammonium, tetraethylammonium, tetrabutylammonium, F - , Cl - , Br - , I - , BF4 - , PF6 - , SbF6 - , AsF6 - , ClO4 - , SO3CF3 - , N(CF3SO2)2 - , C(CF3SO2)3 - , N(SO2C2F5)2, Al(OC(CF3)3)4 - , BAr4 - or a mixture of these anions, where Ar is an aryl group or a fluorinated aryl group. In some embodiments, the anion is PF6 - or SO3CF3 -For example, the anion may be tetraethylammonium hexafluorophosphate. The electrolyte crosslinker 50 may be one or more polyisocyanates, such as, but not limited to, hexamethylene 1,6-diisocyanate, isocyanurate trimer, tolylene-2,4-diisocyanate, 4,4'-methylenebis(phenylisocyanate), polymers of hexamethylene-1,6-diisocyanate (Covestro N3300A, Desmodur RC, Vestanat T1890 / 100, and Desmodur Light); the electrolyte polymer 52 may be a polyol copolymer having a molar ratio of 2-hydroxyethyl methacrylate and methyl acrylate of 1 / 20 to 1 / 5; and the electrolyte solvent 54 may be selected from the group consisting of, but not limited to, propylene carbonate, acetonitrile, γ-butyrolactone, γ-valerolactone, or 3-methoxypropionitrile. In the electro-optic assembly 10, the electrolyte salt 48 flows between the anode electro-optic film 44 and the cathode electro-optic film 46 to balance the charge difference caused by electrons flowing into or out of the cathode film 44 and the anode film 46 from the first conductive layer 32 and the second conductive layer 34. The electrolyte cross-linker 50 forms a bond (i.e., a covalent bond) between the electrolyte cross-linker 50 and the electrolyte polymer 52. Each of the first electrolyte salt 48, the electrolyte cross-linker 50, and the electrolyte polymer 52 may be initially deposited in an electrolyte solvent 54 such that the electrolyte medium 30 is a homogenous mixture. As described in more detail below, the electrolyte medium 30 may be backfilled into the cavity 28 after the seal 42 is deposited and cured.

[0022] 2, examples of materials for the cathodic electro-optic film 46 are provided in accordance with various embodiments. The cathodic electro-optic film 46 may be formed using a polymer matrix film containing a crosslinker 56 (i.e., a second crosslinker), a cathodic redox buffer 58, and a first cathodic species 60. The crosslinker 56 includes a polyisocyanate (e.g., an isocyanurate trimer of hexamethylene 1,6-diisocyanate, also referred to herein as "HDT"). The cathodic redox buffer 58 includes an octamethyl dihexanol ferrocinium BF4 salt, and the cathodic species is a viologen-type chromophore 60 N,N'-bis(6-hydroxyhexyl)-4,4'-bipyridinium di(bis(trifluoromethane)sulfonimide) or 1,1'-bis(hexanol)-4,4'-dipyridinium (NTF)2. During curing, the crosslinker 56 forms urethane bonds (i.e., covalent bonds) between the molecules of the cathodic species 60. The cathodic redox buffer 58 stabilizes the cathodic electro-optic film 46 during the redox reaction of the electro-optic assembly 10 by providing long term thermal and cyclic testing. FIG. 3 illustrates the absorption spectrum of the cathodic film 46 in the dark. Of course, other cathodic species having similar absorption spectra and redox potentials may be substituted, and additional materials such as solvents (e.g., propylene carbonate, acetonitrile, γ-butyrolactone, γ-valerolactone, or 3-methoxypropionitrile), surfactants (e.g., TEGO Glide 410), and urethane catalysts (e.g., dibutyltin diacetate) may be incorporated into the cathodic electro-optic film 46 before or after deposition.

[0023] 4, examples of materials for the anodic electro-optic film 44 are provided in accordance with various embodiments. The anodic electro-optic film 44 may be formed using a polymer matrix film that contains a crosslinker 62, an anodic redox buffer 64, a first variant (unsubstituted) or "variant 1" anodic species 66, and a second variant (substituted) or "variant 2" anodic species 68. The crosslinker 62 includes one or more polyisocyanates (e.g., isocyanurate trimer of hexamethylene 1,6-diisocyanate, tolylene-2,4-diisocyanate, 4,4'-methylenebis(phenylisocyanate), polymers of hexamethylene-1,6-diisocyanate, Covestro N3300A, Desmodur RC, Vestanat T1890 / 100, and Desmodur MR Mondur Light). The anodic redox buffer 64 includes octamethyldihexanol ferrocene, the first anodic species 66 includes a material selected from a first group of anodic species, and the second anodic species 68 includes a material selected from a second group of anodic species. In the electro-optic assembly 10, the cross-linking agent 62 forms urethane bonds (i.e., covalent bonds) between the molecules of the first anodic species 66 and the molecules of the second anodic species 68. The anodic redox buffer 64 consumes any excess oxidizing species in the electro-optic assembly 10, which extends the operating life of the electro-optic assembly 10 in thermal and cyclic tests. On the other hand, the cathodic redox buffer 58 consumes excess reducing species in the electro-optic assembly 10, which further extends the life of the electro-optic assembly 10. Of course, other anodic species having similar absorption spectra may be substituted, and additional materials such as solvents (e.g., propylene carbonate and / or 3-methoxypropionitrile), surfactants (e.g., TEGO Glide 410), and urethane catalysts (e.g., dibutyltin diacetate) may be incorporated into the anodic electro-optic film 44 before or after deposition.

[0024] Referring now to FIG. 5, in some embodiments, Variant 1 anode species 66 is: (a) a first anode species 66A of variant 1 comprising a 5,10-bis(hydroxyalkyl)-5,10-dihydrophenazine structure having R1 and R2 as an alkyl chain, or an alkyl chain having a dimethylammonio group in the chain and a hydroxyl end group; (b) a second anodic species 66B of Variant 1 comprising 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]-5,10-dihydrophenazine having a counterion designated by "X"; (c) a third anodic species of variant 1, 66C, containing 5,10-bis(6-hydroxyhexyl)-5,10-dihydrophenazine; (d) a fourth anode species 66D of Variant 1 comprising 5,10-bis(3-hydroxypropyl)-5,10-dihydrophenazine; and

[0025] 6 illustrates the absorption spectrum of an anodic electro-optic film 44 in the darkened state containing a single anodic species selected from the Variant 1 anodic species across varying wavelengths in an electro-optic assembly 10. The Variant 1 anodic species in this example includes 66B (X=PF6). FIG. 7 illustrates the absorption spectrum across the visible spectrum of an electro-optic assembly 10 in the darkened state containing an anodic electro-optic film 44 and a cathodic electro-optic film 46 containing a single Variant 1 compound including the anodic species 66B (X=PF6). Of course, other anodic species having similar absorption spectra and redox potentials may be substituted.

[0026] Referring now to FIG. 8, in some embodiments, the anode species 68 of Variant 2 is: (a) a first anode species 68A of variant 2 comprising an alkyl chain having R1 and R2 as an alkyl chain, or an alkyl chain having dimethylammonio groups in the chain and hydroxyl end groups, and R3 and R4 alkyl groups; (b) a second anodic species of variant 2 (68B) comprising 5,10-bis(hydroxyalkyl)-2,8-di(alkyl)-5,10-dihydrophenazine having R1 and R2 as alkyl chains, or alkyl chains having dimethylammonio groups within the chain and hydroxyl end groups and the R3 and R4 alkyl groups; (c) a third anodic species of variant 2, 68C, comprising 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]2,7-di(tert-butyl)-5,10-dihydrophenazine having a counterion designated X-; (d) a fourth anodic species of variant 2, 68D, comprising 5,10-bis(6-hydroxyhexyl)-2,7-di(tert-butyl)-5,10-dihydrophenazine; (e) a fifth anode species 68E of variant 2 comprising 5,10-bis(3-hydroxypropyl)-2,7-di(tert-butyl)-5,10-dihydrophenazine; and

[0027] Figure 9 illustrates the absorption spectrum of an anodic electro-optic film 44 in the darkened state containing a single anodic species selected from Variant 2 anodic species across varying wavelengths. In this example, the Variant 2 compound includes 68C (X = PF6). Figure 10 illustrates the absorption spectrum across the visible spectrum of an electro-optic assembly 10 in the darkened state containing an anodic electro-optic film 44 and a cathodic electro-optic film 46 containing a single Variant 2 anodic compound including 68C (X = PF6). Of course, other anodic species having similar absorption spectra and redox potentials may be substituted.

[0028] FIG. 11 provides a specific example of the formulation of the anodic electro-optic film 44 and cathodic electro-optic film 46 prior to deposition. The formulation provides the weight percentage of each component, with the first anodic species 66 comprising approximately 60% by weight of the total weight of the first anodic species 66 and the second anodic species 68, which corresponds to a molar ratio of 65% between the first anodic species 66 and the second anodic species 68. FIG. 12 provides an absorption spectrum of the electro-optic assembly 10 using a molar ratio of 60% of the first anodic species 66 to 40% of the second anodic species 68. However, it will be appreciated that other molar ratios of the first anodic species 66 to the second anodic species 68 may be used. For example, the first anodic species 66 may comprise a molar ratio of 90% or less, 80% or less, e.g., 70% or less, 60% or more by weight, 50% or more, 70% to 60%, about 65%, 65%, or 62% to 68%. 13 provides an absorption spectrum in which the first anodic species 66 comprises approximately 80% of the total moles of the first anodic species 66 and the second anodic species 68. It is noted that the concentration of the first anodic species 60 should be substantially uniform across the cathodic electro-optic film 46, which may be achieved by depositing the components of the cathodic electro-optic film 46 into a solvent and forming a homogeneous mixture prior to deposition on the second conductive layer 34. Similarly, it is noted that the molar ratio of the first anodic species 66 to the second anodic species 68 should be substantially uniform across the anodic electro-optic film 44, which may be achieved by depositing the components of the anodic electro-optic film 44 into a solvent and forming a homogeneous mixture prior to deposition on the first conductive layer 32.

[0029] FIG. 14 provides a table summarizing the performance indices obtained and compared at varying voltages of 0.4 to 0.7 V from the three electro-optical assembly 10 types. Generally speaking, however, the varying voltage (i.e., applied voltage range) may be anywhere from 0.0 V to 1.0 V. The first device has only the second anode species 66B of variant 1, which includes (5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]-5,10-dihydrophenazine bis(hexafluorophosphate), (X=PF6)). The second device has only the third anode species 68C of variant 2, which includes (5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]-2,7-di(tert-butyl)-5,10-dihydrophenazine bis(hexafluorophosphate) (X=PF6)). The third electro-optical assembly of Figure 14 has an anodic film with a 65:35 molar ratio of variant 1 anodic species to variant 2 anodic species of 66B(X=PF6):68C(X=PF6). Notably, the third electro-optical assembly of Figure 14 exhibits a much smaller shift in both a* and b* over applied voltage while maintaining a similar transmission state.

[0030] Figure 15 provides a color shift graph for the transition from clear to fully dark, where metrics are taken from the three electro-optic assemblies 10 from Figure 14. Notably, the electro-optic assembly 10 containing a 65:35 molar ratio of anodic species 66B (X=PF6):68C (X=PF6) exhibits much smaller color shifts in both a* and b* during the transition and at the fully dark state.

[0031] Figure 16 provides another color shift graph of the third electro-optic assembly 10 of Figure 14 over various applied voltages. The color shift graph for the intermediate dark state, where the index is obtained from an electro-optic assembly 10 having a molar ratio of anode species 66B (X = PF6):68C (X = PF6) of 65:35. The electro-optic assembly 10 remains within a narrow color range in the intermediate and even fully darkened states.

[0032] FIG. 17 provides another example of color shift for a 10% low end transmission part that maintains color from 86% to 10% transmission range. The electro-optic assembly 10 includes an anode mixture with a molar ratio of 65:35 anode species 66B (X=SO3CF3):68C (X=SO3CF3). The electro-optic assembly 10 maintains a* and b* color from -4 to 4 throughout the device's transition from clear to dark (1) and back to clear (2). The arrows indicate the direction from clear to dark for curve (1) and from dark to clear for curve (2).

[0033] The present disclosure also provides a method of assembling the electro-optic assembly 10. The method includes coating the cathodic electro-optic film 46 onto the second substrate 20 with a Mayer rod. The method may further include leveling the cathodic electro-optic film 46 to obtain a uniform coating thickness across the second substrate 20. The method may further include curing the cathodic electro-optic film 46 (e.g., in an oven at 60° C.). The method may also include removing the edges of the cathodic electro-optic film 46 and then observing the cathodic electro-optic film 46 for uniform thickness (e.g., via a readable machine). The method may further include coating the first substrate 12 with the anodic electro-optic film 44. The method may also include an additional step of anodic electro-optic film similar to that described above for the cathodic electro-optic film. The method may further include placing a seal 42 around the periphery of the anodic electro-optic film 44 and the cathodic electro-optic film 46 and curing (e.g., in an oven at 60° C.) the partially assembled electro-optic assembly 10. The method may also include depositing the electrolyte medium 30 into the cavity 28. The method may further include curing (e.g., in an oven) the assembled electro-optic assembly 10.

[0034] The invention disclosed herein is further summarized in the following paragraphs and is further characterized by any and all combinations of the various aspects described therein.

[0035] According to one aspect of the disclosure, an electro-optic assembly includes a first substrate having a first surface and a second surface disposed on opposing sides thereof, and a second substrate having a third surface and a fourth surface disposed on opposing sides thereof. The second substrate is disposed in a substantially parallel spaced apart relationship with the first substrate, such that the second surface and the third surface face each other. A first conductive layer is disposed on the second surface, and a second conductive layer is disposed on the third surface. A cathodic electro-optic film is in contact with the second conductive layer and includes a cathodic species. An anodic electro-optic film is in contact with the first conductive layer. The anodic electro-optic film includes a plurality of anodic species mixed in a molar ratio configured to generally maintain the a* and b* values ​​of the electro-optic assembly, both of which remain between a high end transmission state and a fully darkened state caused by an applied voltage range of -8 to 8. An electrolyte medium is disposed between the cathodic electro-optic film and the anodic electro-optic film.

[0036] According to another embodiment of the present disclosure, the plurality of anode species includes a first anode species and a second anode species, the first anode species comprising a molar percentage of 80%-60% of the sum of the first anode species and the second anode species.

[0037] According to yet another aspect of the present disclosure, the first anode species is selected from the anode species Variant 1 (unsubstituted) group, which includes unsubstituted phenazine compounds. The anode species Variant 1 (unsubstituted) group includes a) 5,10-bis[(hydroxyalkyldimethylammonio)alkyl]-5,10-dihydrophenazine, and b) 5,10-bis(hydroxyalkyl)-5,10-dihydrophenazine.

[0038] According to yet another embodiment of the present disclosure, the first anode species is selected from the group of anode species variant 1 (unsubstituted) comprising a) 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]-5,10-dihydrophenazine, and b) 5,10-bis(6-hydroxyhexyl)-5,10-dihydrophenazine.

[0039] According to another aspect of the disclosure, the second anodic species is selected from the group of anodic species variant 2 (substituted) which includes substituted alkyl groups at the 2 and 7, or 2 and 8 positions of the unsubstituted phenazine compound. The group of anodic species variant 2 (substituted) includes a) 5,10-bis[(hydroxyalkyldimethylammonio)alkyl]2,7-bis(alkyl)-5,10-dihydrophenazine, b) 5,10-bis(hydroxyalkyl)-2,7-bis(alkyl)-5,10-dihydrophenazine, c) 5,10-bis[(hydroxyalkyldimethylammonio)alkyl]2,8-bis(alkyl)-5,10-dihydrophenazine, and d) 5,10-bis(hydroxyalkyl)-2,8-bis(alkyl)-5,10-dihydrophenazine.

[0040] According to yet another aspect of the disclosure, the second anodic species is selected from the group of anodic species variant 2 (substituted) containing substituted butyl groups at the 2 and 7, or 2 and 8 positions of an unsubstituted phenazine compound. The group of anodic species variant 2 (substituted) includes a) 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]2,7-di(tert-butyl)-5,10-dihydrophenazine, b) 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]2,8-di(tert-butyl)-5,10-dihydrophenazine, c) 5,10-bis(6-hydroxyhexyl)-2,7-di(tert-butyl)-5,10-dihydrophenazine, and d) 5,10-bis(6-hydroxyhexyl)-2,8-di(tert-butyl)-5,10-dihydrophenazine.

[0041] According to yet another aspect of the present disclosure, the phenazine compound is F - , Cl - , Br - , I - , BF4 - , PF6 - , SbF6 - , AsF6 - , ClO4 - , SO3CF3 - , N(CF3SO2)2 - , C(CF3SO2)3 -, N(SO2C2F5)2 - , Al(OC(CF3)3)4 - , BAr4 - , PF6 - and SO3CF3, or a mixture of anions thereof, where Ar is an aryl or fluorinated aryl group.

[0042] According to another aspect of the present disclosure, the cathodic electro-optic film includes cross-linker binding molecules of cathodic species into a polymer matrix.

[0043] According to yet another aspect of the present disclosure, the anodic electro-optic film includes a cross-linking agent that bonds molecules of the first anodic species and molecules of the second anodic species into a polymer matrix.

[0044] According to yet another embodiment of the present disclosure, the applied voltage range is 0.0V to 1.0V.

[0045] According to another aspect of the present disclosure, the transmission state of the electro-optic assembly varies from at least 75% in a high-end transmission state to less than 30% in a completely dark state.

[0046] According to yet another embodiment of the present disclosure, the first anodic species and the second anodic species each include a first redox potential within a range of 200 mV.

[0047] According to another embodiment of the present disclosure, the molar ratio is further configured to maintain a total color shift of a* and b* values, both between -8 and 8, throughout the entire applied voltage range.

[0048] According to yet another embodiment of the present disclosure, the molar ratio is further configured to maintain a total color shift of both a* and b* values ​​between −6 and 6 throughout the entire applied voltage range.

[0049] According to yet another embodiment of the present disclosure, the molar ratio is further configured to maintain a total color shift of both a* and b* values ​​from −4 to 4 throughout the entire applied voltage range.

[0050] According to another aspect of the present disclosure, the cathodic electro-optic film includes a cross-linking agent, the anodic electro-optic film contains a cross-linking agent, and the electrolyte medium contains an electrolyte cross-linking agent and an electrolyte polymer.

[0051] According to yet another aspect of the present disclosure, the cathodic species is a viologen.

[0052] According to another aspect of the disclosure, an electro-optic assembly includes a first substrate having a first surface and a second surface disposed on opposing sides thereof, and a second substrate having a third surface and a fourth surface disposed on opposing sides thereof. The second substrate is disposed in a substantially parallel spaced apart relationship with the first substrate, such that the second surface and the third surface face each other. A first conductive layer is disposed on the second surface, and a second conductive layer is disposed on the third surface. A cathodic electro-optic film is in contact with the second conductive layer and includes a cathodic species. An anodic electro-optic film is in contact with the first conductive layer. The anodic electro-optic film includes a plurality of anodic species mixed in a molar ratio configured to generally maintain the a* and b* values ​​of the electro-optic assembly, both of which remain between -8 and 8 between a high end transmission state and a fully darkened state caused by an applied voltage range. The plurality of anode species includes a first anode species and a second anode species, the first anode species comprising a molar percentage of the sum of the first anode species and the second anode species between 80% and 60%. An electrolyte medium is disposed between the cathodic electro-optic film and the anodic electro-optic film.

[0053] According to another embodiment of the present disclosure, the first anodic species includes 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]-5,10-dihydrophenazine having a counterion.

[0054] According to yet another embodiment of the present disclosure, the second anodic species includes 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]2,7-di(tert-butyl)-5,10-dihydrophenazine having a counterion.

[0055] Those skilled in the art will appreciate that the disclosed and other component structures described are not limited to any particular materials. Other exemplary embodiments of the disclosures disclosed herein may be formed from a wide variety of materials unless otherwise stated herein.

[0056] For purposes of this disclosure, the term "coupled" (in all of its forms such as couple, coupling, coupled, etc.) generally means the coupling (electrical or mechanical) of two components directly or indirectly to one another. Such coupling may be fixed in nature or movable in nature. Such coupling may be achieved by means of the two components (electrical or mechanical) and any additional intermediate members integrally formed with one another or with the two components as a single, inseparable body. Such coupling may be permanent in nature or removable or releasable in nature, unless otherwise specified.

[0057] It is also important to note that the structure and arrangement of the elements of the present disclosure as shown in the exemplary embodiments are merely illustrative. Although only a few embodiments of the present innovation have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily recognize that numerous modifications (e.g., variations in the sizes, dimensions, structures, shapes, and proportions of the various elements, parameter values, mounting arrangements, use of materials, colors, orientations, etc.) are possible without substantially departing from the novel teachings and advantages of the detailed subject matter. For example, elements shown as integrally formed may be constructed of multiple pieces, or elements shown as multiple pieces may be integrally formed, the operation of interfaces may be reversed or otherwise altered, the structure of the system and / or the length or width of members or connectors or other elements may be altered, or the nature or number of adjustment positions provided between elements may be altered. It is noted that the elements and / or assemblies of the system may be constructed in any of a wide variety of colors, textures, and combinations from any of a wide variety of materials that provide sufficient strength or durability. As a result, all such modifications are intended to be within the scope of the present innovation. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the desired and other exemplary embodiments without departing from the spirit of the innovation.

[0058] It will be understood that any described process or step within a described process may be combined with other disclosed processes or steps to form structures within the scope of the present disclosure. The exemplary structures and processes disclosed herein are for illustrative purposes and are not to be construed as limiting.

[0059] It is also, of course, understood that variations and modifications can be made to the structures and methods described above without departing from the concepts of the present disclosure, and further that such concepts are intended to be covered by the following claims unless those claims expressly state otherwise by their language.

Claims

1. 1. An electro-optic assembly comprising: a first substrate having a first surface and a second surface disposed on opposite sides thereof; a second substrate having a third surface and a fourth surface disposed on opposite sides thereof, the second substrate being disposed in a substantially parallel spaced apart relationship with the first substrate such that the second and third surfaces face one another; a first conductive layer disposed on the second surface; a second conductive layer disposed on the third surface; and a cathodic electro-optic film in contact with the second conductive layer and including a cathodic species; an anodic electro-optic film in contact with the first conductive layer, the anodic electro-optic film comprising a plurality of anodic species, both mixed in a molar ratio configured to generally maintain the a* and b* values ​​of the electro-optic assembly remaining between −8 and 8 between a high end transmission state and a fully darkened state produced by an applied voltage range; an electrolyte medium disposed between the cathodic electro-optic film and the anodic electro-optic film.

2. 2. The electro-optic assembly of claim 1, wherein the plurality of anode species comprises a first anode species and a second anode species, the first anode species comprising a molar percentage of the sum of the first anode species and the second anode species that is between 80% and 60%.

3. The first anodic species is selected from the Variant 1 (unsubstituted) group of anodic species comprising an unsubstituted phenazine compound, the Variant 1 (unsubstituted) group of anodic species comprising: (a) 5,10-bis[(hydroxyalkyldimethylammonio)alkyl]-5,10-dihydrophenazine, 3. The electro-optic assembly of claim 2, comprising: (b) 5,10-bis(hydroxyalkyl)-5,10-dihydrophenazine.

4. The first anode species is (a) 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]-5,10-dihydrophenazine, 3. The electro-optic assembly of claim 2, wherein the anode species is selected from the group of variant 1 (unsubstituted) comprising: (b) 5,10-bis(6-hydroxyhexyl)-5,10-dihydrophenazine;

5. The second anodic species is selected from the Variant 2 (Substitution) group of anodic species comprising alkyl groups substituted at the 2 and 7, or 2 and 8 positions of an unsubstituted phenazine compound, the Variant 2 (Substitution) group of anodic species being: (a) 5,10-bis[(hydroxyalkyldimethylammonio)alkyl]2,7-bis(alkyl)-5,10-dihydrophenazine; (b) 5,10-bis(hydroxyalkyl)-2,7-bis(alkyl)-5,10-dihydrophenazine; (c) 5,10-bis[(hydroxyalkyldimethylammonio)alkyl]2,8-bis(alkyl)-5,10-dihydrophenazine; 3. The electro-optic assembly of claim 2, comprising: (d) 5,10-bis(hydroxyalkyl)-2,8-bis(alkyl)-5,10-dihydrophenazine.

6. The phenazine compound is F - , Cl - , Br - , I - , B.F. 4 - , P.F. 6 - , SbF 6 - , AsF 6 - , ClO 4 - , S.O. 3 CF 3 - , N(CF 3 SO 2 ) 2 - , C(CF 3 SO 2 ) 3 - , N(SO 2 C 2 F 5 ) 2 , Al(OC(CF 3 ) 3 ) 4 - , BAr 4 - , P.F. 6 - 6. The electro-optic assembly of claim 5, wherein Ar is an ammonium salt having an anion comprising at least one of: SO3CF3, or a mixture of anions thereof, and Ar is an aryl or fluorinated aryl group.

7. The second anodic species is selected from the group of variant 2 (substituted) anodic species comprising butyl groups substituted at the 2 and 7, or 2 and 8 positions of an unsubstituted phenazine compound, the variant 2 (substituted) group of anodic species being: (a) 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]2,7-di(tert-butyl)-5,10-dihydrophenazine, (b) 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]2,8-di(tert-butyl)-5,10-dihydrophenazine, (c) 5,10-bis(6-hydroxyhexyl)-2,7-di(tert-butyl)-5,10-dihydrophenazine, 3. The electro-optic assembly of claim 2, comprising: (d) 5,10-bis(6-hydroxyhexyl)-2,8-di(tert-butyl)-5,10-dihydrophenazine.

8. The phenazine compound is F - , Cl - , Br - , I - , B.F. 4 - , P.F. 6 - , SbF 6 - , AsF 6 - , ClO 4 - , S.O. 3 CF 3 - , N(CF 3 SO 2 ) 2 - , C(CF 3 SO 2 ) 3 - , N(SO 2 C 2 F 5 ) 2 , Al(OC(CF 3 ) 3 ) 4 - , BAr 4 - , P.F. 6 - 8. The electro-optic assembly of claim 7, wherein Ar is an ammonium salt having an anion comprising at least one of: SO3CF3, or a mixture of anions thereof, and Ar is an aryl or fluorinated aryl group.

9. Electro-optic assembly according to any of the preceding claims, wherein said cathodic electro-optic film comprises cross-linker binding molecules of said cathodic species into a polymer matrix.

10. 9. An electro-optic assembly according to any of claims 1 to 8, wherein the anodic electro-optic film comprises cross-linker binding molecules of the first anodic species and molecules of the second anodic species into a polymer matrix.

11. 9. An electro-optical assembly according to claim 1, wherein the applied voltage range is from 0.0V to 1.0V.

12. 10. The electro-optic assembly of claim 1, wherein the transmission state of the electro-optic assembly varies from at least 75% in the high end transmission state to less than 30% in the completely dark state.

13. 3. The electro-optic assembly of claim 2, wherein the first anodic species and the second anodic species each comprise a first redox potential within a range of 200 mV.

14. 2. The electro-optic assembly of claim 1, wherein said molar ratio is further configured to maintain a total color shift of said a* and b* values, both from -8 to 8, throughout said applied voltage range.

15. 15. The electro-optic assembly of claim 14, wherein the molar ratio is further configured to maintain the total color shift of the a* and b* values ​​both from -6 to 6 throughout the applied voltage range.

16. 16. The electro-optic assembly of claim 15, wherein the molar ratio is further configured to maintain the total color shift of the a* and b* values ​​both from -4 to 4 throughout the applied voltage range.

17. 3. The electro-optic assembly of claim 1, wherein the anodic electro-optic film comprises a first cross-linking agent, the cathodic electro-optic film comprises a second cross-linking agent, and the electrolyte medium comprises an electrolyte cross-linking agent and an electrolyte polymer.

18. 9. An electro-optic assembly according to any preceding claim, wherein the cathodic species is a viologen.

19. 1. An electro-optic assembly comprising: a first substrate having a first surface and a second surface disposed on opposite sides thereof; a second substrate having a third surface and a fourth surface disposed on opposite sides thereof, the second substrate being disposed in a substantially parallel spaced apart relationship with the first substrate such that the second and third surfaces face one another; a first conductive layer disposed on the second surface; a second conductive layer disposed on the third surface; and a cathodic electro-optic film in contact with the second conductive layer and including a cathodic species; an anodic electro-optic film in contact with the first conductive layer, the anodic electro-optic film comprising a plurality of anodic species, both mixed in a molar ratio configured to generally maintain the a* and b* values ​​of the electro-optic assembly remaining between −8 and 8 between a high end transmission state and a fully darkened state produced by an applied voltage range; the plurality of anodic species comprising a first anodic species and a second anodic species, the first anodic species comprising a molar percentage of the sum of the first anodic species and the second anodic species between 80% and 60%; an electrolyte medium disposed between the cathodic electro-optic film and the anodic electro-optic film.

20. 20. The electro-optic assembly of claim 19, wherein the first anodic species comprises 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]-5,10-dihydrophenazine with a counterion.

21. 21. An electro-optic assembly according to claim 19 or 20, wherein the second anodic species comprises 5,10-bis[4-(3-hydroxypropyldimethylammonio)butyl]2,7-di(tert-butyl)-5,10-dihydrophenazine having a counterion.

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