Electrochromic devices having reduced switching times and their methods of manufacture

Electrochromic devices having reduced switching times and their methods of manufacturing are presented. In one instance, the electrochromic device includes a transparent substrate having a surface. A first transparent conductive layer is disposed on a portion of the surface. The electrochromic device also includes an optically active layer disposed on the first transparent conductive layer. The optically active layer is configured to alter optical properties in response to an applied electric field. A second transparent conductive layer is disposed on the optically active layer. The electrochromic device additionally includes a patterned conductive layer disposed on the second transparent conductive layer and defining an array on the second transparent conductive layer. The array partitions the electrochromic device into a plurality of electrochromic cells. Other electrochromic devices and methods are presented.

FIELD

The described embodiments relate generally to electrochromic devices, and more particularly, to electrochromic devices having patterned conductors for reducing switching times.

BACKGROUND

Electrochromic devices include an optically active layer disposed between two conductive layers. The two conductive layers are transparent, and during operation, apply voltages to the optically active layer. Such voltages correspond to electric fields passing through the optically active layer. The optically active layer is formed of materials whose light transmittance changes in response to applied electric fields. Thus, each applied voltage induces a transmissive state in the optically active layer. By selectively manipulating the applied voltage, electrochromic devices can switch into a desired transmissive state and regulate light passing therethrough. In general, increased voltages correspond to transmissive states that have a lower transmittance of light.

Electrochromic devices have been integrated into glass panes to produce so-called “smart windows” that selectively regulate light transmission. Within a “smart window,” an electrochromic device spans a functional area of a glass pane, which can be the entirety of the pane. In this configuration, electrical coupling to conductive layers occurs from a perimeter of the glass pane, thereby requiring an electrical charge to move inward when voltages are applied. For this reason, conventional “smart windows” are observed to first darken (or lighten) from their edges to achieve a uniform transmissive state. This darkening (or lightening) then travels inward. Such an effect creates delays when switching between transmissive states.

The delayed switching times can be influenced by sheet resistances associated with the two conductive layers. In operation, electrical charges traveling inward from the perimeter must overcome a cumulative resistance that increases with distance. Thus, during operation, a voltage distribution across the two conductive layers is initially non-uniform, i.e., voltages experienced by the optically active layer can decrease when traveling inward and away from the perimeter. Thus, there is a need for electrochromic devices that reduce sheet resistance effects associated with the conductive layers.

SUMMARY

The embodiments described herein relate to electrochromic devices having reduced switching times, including methods for manufacturing such electrochromic devices. In one illustrative embodiment, the electrochromic device includes a transparent substrate having a surface. A first transparent conductive layer is disposed on a portion of the surface. The electrochromic device also includes an optically active layer disposed on the first transparent conductive layer. The optically active layer is configured to alter optical properties in response to an applied electric field (i.e., an applied voltage). A second transparent conductive layer is disposed on the optically active layer. The electrochromic device additionally includes a patterned conductive layer disposed on the second transparent conductive layer and defining an array on the second transparent conductive layer. The array partitions the electrochromic device into a plurality of electrochromic cells.

In another illustrative embodiment, the electrochromic device includes a glass substrate having a surface. A first transparent conductive layer is disposed on a portion of the surface. The electrochromic device also includes an optically active layer disposed on the first transparent conductive layer and having an electrochromic layer, an ion conductive layer, and an ion storage layer therein. The optically active layer is configured to alter an absorption spectrum of electromagnetic radiation in response to an applied electric field (i.e., an applied voltage). A second transparent conductive layer is disposed on the optically active layer. The electrochromic device additionally includes a patterned conductive layer disposed on the second transparent conductive layer, defining an array on the second transparent conductive layer. The array partitions the electrochromic device into a plurality of electrochromic cells. The electrochromic device also includes a glass superstrate having a portion bonded onto the patterned conductive layer.

In an additional illustrative embodiment, a method of manufacturing an electrochromic device includes forming an optically active layer onto a first transparent conductive layer. The optically active layer is configured to alter optical properties in response to an applied electric field. The first transparent conductive layer is disposed on a portion of a transparent substrate. The method also includes depositing a second transparent conductive layer onto the optically active layer and patterning a conductive material into an array on the second transparent conductive layer. The array partitions the electrochromic device into a plurality of electrochromic cells.

It will be appreciated that the patterned conductive layer has a greater conductivity than the second transparent conductive layer. This greater conductivity enables an alternate, lower-resistance electrical conduit that mitigates sheet resistance effects. Electrical charge can therefore reach areas throughout the second transparent conductive layer, but with minimal losses in voltage potential. Moreover, the plurality of electrochromic cells subdivides the electrochromic device into smaller regions, allowing the optically active layer to experience a more uniform voltage distribution. Deviations from the applied voltage are also significantly reduced. Thus, by virtue of the patterned conductive layer, the transmissive state emerges more evenly throughout the optically active layer and switching times between transmissive states are reduced. In some embodiments, features of the array are such that the patterned conductive layer is not visible to the naked eye. Other electrochromic devices and methods are presented.

DETAILED DESCRIPTION

Referring toFIG. 1A, a perspective view is presented, with a portion shown in cross-section, of a window100having a plurality of selectively transparent panels102, according to an illustrative embodiment.FIG. 1Apresents the window100in the context of a building structure. However, other contexts are possible (e.g., vehicular windows). Moreover, the window100is depicted as being exposed to solar radiation104from the sun106. This depiction, however, is not intended as limiting. The window100, for example, could be disposed within an interior room of a building. Other environments are possible. The plurality of selectively transparent panels102have a planar configuration and are individually supported within a frame108of the window100. It will be appreciated, however, that the plurality of selectively transparent panels102can have non-planar configurations (e.g., concave, convex, etc.). For example, and without limitation, the plurality of selectively transparent panels102could function as windows for a vehicle and have shapes that conform thereto (i.e., curved to match a profile of the vehicle

An electrochromic device110can be incorporated into each of the plurality of selectively transparent panels102. The electrochromic device110interacts with an incoming light112that enters the window100. For purposes of clarity,FIG. 1Adepicts only one selectively transparent panel102interacting with the incoming light112. However, it will be understood that all panels102of the plurality of selectively transparent panels102are capable of interacting with the incoming light112. Interaction of the electrochromic device110with the incoming light112produces a transmitted light114. The transmitted light114can be reduced in intensity relative to the incoming light112. However, the electrochromic device110may also alter a spectral distribution, a polarization, or both, of the incoming light112to produce the transmitted light114. In some embodiments, interaction of the electrochromic device110with the incoming light112may also produce a reflected light116. Non-limiting examples of the incoming light112include the sun, incandescent lamps, fluorescent lamps, LED lamps, and combustion lamps. Other sources for the incoming light112are possible.

FIG. 1Bpresents a detail view, shown in cross-section, of the electrochromic device110incorporated into each of the plurality of selectively transparent panels102ofFIG. 1A. The electrochromic device110includes an optically active layer118disposed between a first transparent conductive layer120and a second transparent conductive layer122. During operation, the first transparent conductive layer120and the second transparent conductive layer122apply a voltage across the optically active layer118thereby generating an applied electric field. The electrochromic device110also includes a patterned conductive layer124disposed on the second transparent conductive layer122. The patterned conductive layer124defines an array on the second transparent conductive layer122and partitions the electrochromic device110into a plurality of electrochromic cells. In some embodiments, features of the array are such that the patterned conductive layer is not visible to the naked eye.

InFIG. 1B, the array is depicted as a rectilinear array. However, this depiction is for purposes of illustration only. The array may include any combination of vertexes and segments therebetween that define a two-dimensional pattern across a surface126of the second transparent conductive layer122. As will be described further in relation toFIG. 2, the patterned conductive layer124reduces sheet resistance effects associated with the second transparent conductive layer122. The electrochromic device110can be disposed between two transparent substrates to create a sandwich structure. In some embodiments, the transparent substrates can be panes of glass128, in other embodiments, the transparent substrates can be polymers, resins, or other types of transparent materials.

In operation, a voltage is applied across the optically active layer118using the first transparent conductive layer120, the second transparent conductive layer122, and the patterned conductive layer124. In response to the applied voltage, the optically active layer118enters a transmissive state that regulates light passing through the electrochromic device110. Such regulation includes altering an intensity of light, a spectral distribution of light, a polarization of light, or any combination thereof.

The transmissive state may be characterized by a percentage that ranges between a minimum transmittance (0% transmittance) and a maximum transmittance (100% transmittance).

By varying the voltage applied to the optically active layer118, different transmissive states can be accessed. Such variation enables the electrochromic device110to selectively control the amount of the transmitted light114from the incoming light112, and/or the amount of the reflected light116. Thus, the electrochromic device110allows the selectively transparent panels102to control their transparency to light. In some embodiments, the voltage can be applied continuously to maintain a selected transmissible state. In other embodiments, the voltage need not be applied continuously to the optically active layer118to maintain the transmissive state. In these embodiments, the voltage need only be applied during a limited duration until the transmissive state is achieved. It will be appreciated that switching between different transmissive states can involve a time delay. This time delay would otherwise scale appreciably with a size of the plurality of selectively transparent panels102if the patterned conductive layer124were not present.

Referring toFIG. 2, a perspective view is presented of a cross-sectioned portion of an electrochromic device200, according to an illustrative embodiment. The electrochromic device200includes a transparent substrate202having a surface204. The transparent substrate202can be formed of an amorphous material such as a soda-lime glass or a borosilicate glass. The electrochromic device200also includes a first transparent conductive layer206disposed on the surface204of the transparent substrate202. The first transparent conductive layer206is commonly a transparent conducting oxide (TCO), although other transparent conducting materials are possible. Non-limiting examples of transparent conducting oxides include F:SnO2, Sn:In2O3, and Al:ZnO. In other embodiments, the transparent conductive layer can be a zinc nitride material or a titanium nitride material.

An optically active layer208is disposed on the first transparent conductive layer206and configured to alter optical properties in response to an applied electric field (i.e., an applied voltage). During operation, the optical properties are altered to interact with an incoming light to produce a transmitted light. Such interaction can involve attenuating a spectral portion of the incoming light. The spectral portion may include an individual wavelength or a range of wavelengths. Attenuation of the incoming light may involve absorption, reflection, polarization, or combinations thereof. Other optical processes are possible. The applied voltage controls strength of attenuation and also establishes a transmissive state in the optically active layer208.

In some embodiments, the optical properties can include an absorption spectrum of electromagnetic radiation. In these embodiments, wavelengths of the spectral portion can be absorbed in proportions defined by the absorption spectrum of electromagnetic radiation. In some embodiments, the optical properties can include a reflection spectrum of electromagnetic radiation. In these embodiments, wavelengths of the spectral portion can be reflected in proportions defined by the reflection spectrum of electromagnetic radiation.

In some embodiments, the optically active layer208can include an electrochromic layer, an ion conductive layer, and an ion storage layer. The electrochromic layer can incorporate a transition metal oxide such as NiO, V2O5, TiO2, Nb2O5, MoO3, Ta2O5, and WO3. Other materials, however, are possible (e.g., electrochromic polymers). The ion-conductive layer, which is disposed between the electrochromic layer and the ion storage layer, can include an electrolyte that allows ions to diffuse therethrough. Such ions may include H+, Li+, Na+, K+, or combinations thereof. The ion-conductive layer may be a polymeric electrolyte or a gel electrolyte. Other types of electrolytes are possible. The ion storage layer, or counter electrode, serves to receive ions from and release ions into the ion conductive layer. The ion storage layer is commonly formed of a transition metal oxide (e.g., NiO, V2O5, TiO2, etc.).

The electrochromic device200includes a second transparent conductive layer210disposed on the optically active layer208. The second transparent conductive layer210can be a transparent conducting oxide (TCO), although other transparent conducting materials are possible. In some embodiments, the second transparent conductive layer210can comprise a transparent conducting oxide that is the same as the first transparent conducting layer206. In other embodiments, the second transparent conductive layer210and the first transparent conductive layer206can be different transparent conducting oxide materials.

The electrochromic device200also includes a patterned conductive layer212disposed on the second transparent conductive layer210and defining an array214on the second transparent conductive layer210. The array214partitions the electrochromic device200into a plurality of electrochromic cells216. InFIG. 2, the array214is depicted as a rectilinear array. However, this depiction is not intended as limiting. The array214may include any pattern that defines two-dimensional cells across a surface of the second transparent conductive layer210. For example, the array can be a series of cells that can be rectilinear, triangular-shaped, diamond-shaped, pentagonal-shaped, hexagonal-shaped, octagonal-shaped, combinations thereof, or any other geometric shape.

In some embodiments, features of the array214are such that the patterned conductive layer212is not visible to the naked eye. For example, and without limitation, the array214may include conductive nanowires. In another non-limiting example, the array214may be formed using a conductive ink that, when hardened or dried, provides semi-transparency. The conductive ink can include a fluid having a transparent, conductive polymer dissolved therein. The conductive ink can also include metallic particles, which may be nanoparticles. Other features, however, are possible for the array214.

To overcome sheet resistances, the patterned conductive layer212can have a greater conductivity than the second transparent conductive layer210. This greater conductivity allows an electrical charge to use the patterned conductive layer212as an alternate, lower-resistance electrical conduit during operation. The electrical charge distributes through the patterned conductive layer212and reaches areas throughout the second transparent conductive layer210having lost minimal voltage potential. Moreover, the plurality of electrochromic cells216subdivides the electrochromic device200into smaller regions, allowing the optically active layer208to experience a more uniform voltage distribution (or distribution in voltage potential). Deviations from the applied voltage can be reduced. Thus, by virtue of the patterned conductive layer212, the transmissive state can emerge more evenly throughout the optically active layer208, and switching times between transmissive states can be reduced.

In some embodiments, the patterned conductive layer212can include a portion that can generate heat by resistive heating. In these embodiments, heat flows through the second transparent conductive layer210and into the optically active layer208.

In some embodiments, the patterned conductive layer212includes a metal selected from the group consisting of copper, aluminum, silver, and gold. In further embodiments, the metal includes nanoparticles having dimensions less than 750 nm. In some embodiments, the patterned conductive layer212includes a polymer material having a resistivity lower than 10−3Ω-cm. In these embodiments, the polymer material may be transparent. Non-limiting examples of the polymer material include PEDOT, i.e., poly(3,4-ethylenedioxythiophene) and PEDOT:PSS, i.e., poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate). In further embodiments, the polymer material incorporates particles of metal therein (e.g., Cu, Al, Ag, Ag, Pt, etc.). In some embodiments, the patterned conductive layer212includes carbon nanomaterials. Non-limiting examples of carbon nanomaterials include graphene, fullerenes, and carbon nanotubes.

In some embodiments, the electrochromic device200can further include a transparent layer, a portion of which forms an interface with the patterned conductive layer212. The transparent layer can be bonded to the patterned conductive layer212, the second transparent conductive layer210, or both. The transparent layer may be a superstrate body, such as a glass pane. The transparent layer may also be a coating, such as an epoxy coating, a thermoplastic coating, or other organic-based coatings.

In some embodiments, the electrochromic device200can further include a power distribution circuit electrically coupled to the first transparent conductive layer206and the patterned conductive layer212. In such embodiments, the power distribution circuit is configured to allow electrical power to selectively flow to individual cells in the plurality of electrochromic cells216. The power distribution circuit may have an electrical power source coupled thereto. In some embodiments, the power distribution circuit includes an electrical switch. In these embodiments, the electrical switch is configured to regulate electrical power flowing to the individual cells in the plurality of electrochromic cells216. This regulation may include selectively applying voltages to individual electrochromic cells216in order to produce patterns of transmissive states across the electrochromic device200. Non-limiting examples of patterns include gradients in shading, step-contrasts between shaded and non-shaded regions, and shading that defines informational characters (e.g., text). Other types of patterns of transmissive states are possible.

In some embodiments, the electrochromic device200further includes a glass superstrate having a portion bonded onto the patterned conductive layer212. In such embodiments, the transparent substrate202is a glass substrate. Moreover, the optically active layer208includes the electrochromic layer, the ion conductive layer, and the ion storage layer. The electrochromic layer is configured to alter the absorption spectrum of electromagnetic radiation in response to the applied electric field. In these embodiments, the patterned conductive layer can include a metal selected from the group consisting of copper, aluminum, silver, and gold. The patterned conductive layer can also include the polymer material having a low resistivity (e.g. lower than 10−3Ω-cm). The polymer material may be utilized independently or in combination with the metal.

In operation, the electrochromic device200receives the incoming light and, depending on the optical properties altered by the optically active layer208, produces the transmitted light.FIG. 3presents a portion of an electrochromic device300, shown in cross-section, in which the optically active layer308includes an electrochromic layer318, an ion conductive layer320, and an ion storage layer322, according to an illustrative embodiment. An incoming light324is received by patterned conductive layer312and traverses the electrochromic device300to exit as a transmitted light326. The transmitted light326is altered relative to the incoming light324due to optical interactions within the optically active layer308.

An electrical power source328is coupled to the patterned conductive layer312and the first transparent conductive layer306via a power distribution circuit330.FIG. 3depicts the electrical power source328as a battery. However, this depiction is for purposes of illustration only. Other types of electrical power sources are possible. The power distribution circuit330enables the electrical power source328to apply a voltage between the patterned conductive layer312and the first transparent conductive layer306. The voltage creates an electric field332within the optically active layer308. An electrical switch334allows the voltage experienced by the electrochromic device300to be adjusted in magnitude. The electric field332scales in proportion to the applied (or adjusted) voltage. InFIG. 3, the electric switch is depicted as a potentiometer. However, this depiction is not intended as limiting. Other types of electric switches are possible (e.g., a transistor). The applied voltage induces a flow of current336within the power distribution circuit330that includes the electrochromic device300. The flow of current336is illustrated inFIG. 3by dashed arrows that represent a motion of negative charge (i.e., a motion of e−). It will be appreciated that the flow of current336moves in a direction opposite of the electric field332when traversing the electrochromic device300.

The flow of current336delivers a negative charge to the electrochromic layer318via the first transparent conductive layer306. In response, positive ions (i.e., M+) diffuse out of the ion storage layer322, through the ion conductive layer320, and into the electrochromic layer318. Such diffusion occurs in a same direction as the applied current336. The diffusion of positive ions338is depicted inFIG. 3by solid arrows. Materials in the electrochromic layer318change composition upon receiving the flow of positive ions338. This compositional change can alter the optical properties of the electrochromic layer318. A non-limiting example of such compositional changes is provided below:
yLi++ye−+WVIO3→LiyWVyWIV1-yO3
In this non-limiting example, lithium ions intercalate into tungsten oxide to produce a lithium tungstate compound. As intercalation proceeds, the lithium tungstate compound alters its absorption spectrum to favor blue wavelengths. Thus, an electrochromic layer incorporating tungsten oxide (i.e., WO3) would become increasingly blue in tint as lithium ions were increasingly absorbed. In other embodiments, other ion-metal oxide compounds can be used to alter the absorption to favor other colors/wavelengths.

The flow of positive ions338continues until the ion storage layer322becomes sufficiently depleted that the strength of the electric field332is unable to extract further ions. At this point, the optically active layer308exhibits a stable transmissive state. In some embodiments, the voltage can be removed yet the transmissive state persists. The optically active layer308can be switched into a new transmissive state by altering the voltage. For example, and without limitation, an electrochromic layer incorporating tungsten oxide (i.e., WO3) can increase in blue tint by applying a voltage higher than the previous voltage. Alternatively, the voltage could be reversed to decrease the blue tint. Other manipulations of the voltage are possible. In general, the voltage applied by the power distribution circuit330can be manipulated by the electrical switch334to transition the electrochromic device300between transmissive states. Such manipulation alters the optical properties of the optically active layer308.

It will be appreciated that the patterned conductive layer312enables a more uniform voltage distribution than if the power distribution circuit330were coupled directly to the second transparent conductive layer210. By virtue of its higher conductivity, the patterned conductive layer312serves as an alternate, lower-resistance electrical conduit for the flow of current336. Moreover, the plurality of electrochromic devices316subdivide the electrochromic device300into smaller regions. The flow of current336therefore is able to distribute across the second transparent conductive layer210with minimal losses in voltage potential. As a result, the transmissive state emerges more evenly throughout the optically active layer308and switching times between transmissive states are reduced. In embodiments where the patterned conductive layer312generates heat, i.e., via a portion thereof, such heat is absorbed by the optically active layer308. This heat increases ion diffusion within the optically active layer308, further reducing switching times.

In some embodiments, the electrochromic device can include two patterned conductive layers. An optically active layer is disposed between the two patterned conductive layers.FIG. 4depicts presents a cross-sectioned portion of an electrochromic device400, according to an illustrative embodiment. The electrochromic device400includes a transparent substrate402. As previously described, the transparent substrate402can be formed of an amorphous material such as, but not limited to, a soda-lime glass or a borosilicate glass. The electrochromic device400also includes a first transparent conductive layer406disposed the transparent substrate402. The first transparent conductive layer406can be a transparent conducting oxide (TCO), although other transparent conducting materials are possible. Non-limiting examples of transparent conducting oxides include F:SnO2, Sn:In2O3, and Al:ZnO. In other embodiments, the transparent conductive layer can be a zinc nitride material or a titanium nitride material.

An optically active layer408is disposed on the first transparent conductive layer406, and is configured to alter optical properties in response to an applied electric field (i.e., an applied voltage). During operation, the optical properties are altered to interact with incoming light to produce transmitted light. Such interaction can involve attenuating a spectral portion of the incoming light. The spectral portion can include an individual wavelength or a range of wavelengths. Attenuation of the incoming light can involve absorption, reflection, polarization, or combinations thereof. Other optical processes are possible. The applied voltage controls strength of attenuation and can also establish a transmissive state in the optically active layer208.

In some embodiments, the optically active layer408can include an electrochromic layer, an ion conductive layer, and an ion storage layer. The electrochromic layer can incorporate a transition metal oxide such as NiO, V2O5, TiO2, Nb2O5, MoO3, Ta2O5, and WO3. Other materials are possible (e.g., electrochromic polymers). The ion-conductive layer, which is disposed between the electrochromic layer and the ion storage layer, can include an electrolyte that allows ions to diffuse therethrough. Such ions may include H+, Li+, Na+, K+, or combinations thereof. The ion-conductive layer may be a polymeric electrolyte or a gel electrolyte. Other types of electrolytes are possible. The ion storage layer, or counter electrode, serves to receive ions from and release ions into the ion conductive layer. The ion storage layer is commonly formed of a transition metal oxide (e.g., NiO, V2O5, TiO2, etc.).

The electrochromic device400includes a second transparent conductive layer410disposed on the optically active layer408. The second transparent conductive layer410can be a transparent conducting oxide (TCO), although other transparent conducting materials are possible. In some embodiments, the second transparent conductive layer410can comprise a transparent conducting oxide that is the same as the first transparent conducting layer406. In other embodiments, the second transparent conductive layer410and the first transparent conductive layer406can be different transparent conducting oxide materials.

The electrochromic device400also includes a first patterned conductive layer412disposed on the first transparent conductive layer406. The electrochromic device400also includes a second patterned conductive layer422disposed on the second transparent conductive layer410. Collectively, the first patterned conductive layer412and the second patterned conductive layer422define an array414that partitions the electrochromic device400into a plurality of electrochromic cells416. The array414partitions the electrochromic device400into a plurality of electrochromic cells416.

InFIG. 4, the array414is depicted as a rectilinear array. However, this depiction is not intended as limiting. The array414may include any pattern that defines three-dimensional cells across the optically active layer408. For example, the array can be a series of cells that can be rectilinear, triangular-shaped, diamond-shaped, pentagonal-shaped, hexagonal-shaped, octagonal-shaped, combinations thereof, or any other geometric shape.

In some embodiments, features of the array414are such that the patterned conductive layers412and422are not visible to the naked eye. For example, and without limitation, the array414may include conductive nanowires. In another non-limiting example, the array414may be formed using a conductive ink that, when hardened or dried, provides semi-transparency. The conductive ink can include a fluid having a transparent, conductive polymer dissolved therein. The conductive ink can also include metallic particles, which may be nanoparticles. Other features, however, are possible for the array414.

To overcome sheet resistances, the patterned conductive layers412and422can have greater conductivity than the first and second transparent conductive layers406and410. This greater conductivity allows an electrical charge to use the patterned conductive layers412and422as an alternate, lower-resistance electrical conduit during operation. The electrical charge distributes through the patterned conductive layers412and422, and reaches areas throughout the transparent conductive layers406and410having lost minimal voltage potential. Moreover, the plurality of electrochromic cells416subdivides the electrochromic device400into smaller regions, allowing the optically active layer408to experience a more uniform voltage distribution (or distribution in voltage potential). Thus, by virtue of the patterned conductive layers412and422, the transmissive state can emerge more evenly throughout the optically active layer408, and switching times between transmissive states can be reduced.

In some embodiments, the electrochromic device400can further include a transparent layer (not shown), a portion of which forms an interface with the second patterned conductive layer422. The transparent layer can be bonded to the second patterned conductive layer422, the second transparent conductive layer410, or both. The transparent layer may be a superstrate body, such as a glass or plexiglass pane. The transparent layer may also be a coating, such as an epoxy coating, a thermoplastic coating, or other organic-based coatings.

In some embodiments, like the electrochromic device200, electrochromic device400can further include a power distribution circuit electrically coupled to the transparent conductive layers406and410and the patterned conductive layers412and422. In such embodiments, the power distribution circuit is configured to allow electrical power to selectively flow to individual cells in the plurality of electrochromic cells416. The power distribution circuit may have an electrical power source coupled thereto. In some embodiments, the power distribution circuit includes an electrical switch. In these embodiments, the electrical switch is configured to regulate electrical power flowing to the individual cells in the plurality of electrochromic cells416. This regulation may include selectively applying voltages to individual electrochromic cells416in order to produce patterns of transmissive states across the electrochromic device400. Non-limiting examples of patterns include gradients in shading, step-contrasts between shaded and non-shaded regions, and shading that defines informational characters (e.g., text). Other types of patterns of transmissive states are possible.

In some embodiments the electrochromic device can have portions of a transparent conductive layer and the optically active layer removed to further partition the device into electrochromic cells.FIG. 5depicts presents a cross-sectioned portion of an electrochromic device500, according to an illustrative embodiment. The electrochromic device500includes a transparent substrate502. As previously described, the transparent substrate502is typically formed of an amorphous material such as a soda-lime glass or a borosilicate glass. The electrochromic device500also includes a first transparent conductive layer506disposed on the transparent substrate502. The first transparent conductive layer506is commonly a transparent conducting oxide (TCO), although other transparent conducting materials are possible. Non-limiting examples of transparent conducting oxides include F:SnO2, Sn:In2O3, and Al:ZnO. In other embodiments, the transparent conductive layer can be a zinc nitride material or a titanium nitride material.

An optically active layer508is disposed on the first transparent conductive layer506and configured to alter optical properties in response to an applied electric field (i.e., an applied voltage). In some embodiments, the optically active layer508can include an electrochromic layer, an ion conductive layer, and an ion storage layer. The electrochromic layer can incorporate a transition metal oxide such as NiO, V2O5, TiO2, Nb2O5, MoO3, Ta2O5, and WO3. Other materials, however, are possible (e.g., electrochromic polymers). The ion-conductive layer, which is disposed between the electrochromic layer and the ion storage layer, can include an electrolyte that allows ions to diffuse therethrough. Such ions may include H+, Li+, Na+, K+, or combinations thereof. The ion-conductive layer may be a polymeric electrolyte or a gel electrolyte. Other types of electrolytes are possible. The ion storage layer, or counter electrode, serves to receive ions from and release ions into the ion conductive layer. The ion storage layer is commonly formed of a transition metal oxide (e.g., NiO, V2O5, TiO2, etc.).

The electrochromic device500includes a second transparent conductive layer510disposed on the optically active layer508. The second transparent conductive layer510can be a transparent conducting oxide (TCO), although other transparent conducting materials are possible. In some embodiments, the second transparent conductive layer510can comprise a transparent conducting oxide that is the same as the first transparent conducting layer506. In other embodiments, the second transparent conductive layer510and the first transparent conductive layer506can be different transparent conducting oxide materials.

The electrochromic device500also includes a first patterned conductive layer512disposed between the first transparent conductive layer506and the optically active layer508. The electrochromic device500also includes a second patterned conductive layer522disposed on the second transparent conductive layer510. Collectively, the first patterned conductive layer512and the second patterned conductive layer522define an array514along with the optically active layer508that partitions the electrochromic device500into a plurality of electrochromic cells516.

Further, the electrochromic cells516can be defined by removing select portions of the optically active layer508and the second transparent conductive layer510. As shown inFIG. 5, it is illustrated that selective portions508aof the optically active layer and selective portions510aof the second transparent conductive layer that correspond to the pattern of the first and second patterned conductive layers512and522are removed. To remove portions508aof the optically active layer and portions510aof the second transparent conductive layer, the optically active layer508and the second transparent conductive layer510can be selectively ablated. In some embodiments, portions508aof the optically active layer and portions510aof the second transparent conductive layer can be removed by laser ablation by heating portions508aand portions510ato evaporate or sublimate the portions. Other possible methods for ablation are possible

In other embodiments, portions508aof the optically active layer and portions510acan be removed by using a lithography process. In such embodiments, the optically active layer may be deposited along with the use of a mask that is patterned. The patterned mask can be overlaid on the first transparent conductive layer506such that regions of the first transparent conductive layer are covered with the mask thereby preventing the deposition of the optically active layer on the first transparent conductive layer506. These regions correspond to portions508aof the optically active layer. Then, the second transparent layer510can be deposited on the optically active layer508while the mask is still overlaid on the first transparent conductive layer506. The regions of the mask that cover the first transparent conductive layer506also correspond to portions510aof the second transparent conductive layer510. After deposition of the optically active layer508and the second transparent conductive layer510, the mask can be removed such that portions of the first transparent conductive layer506are exposed. Then, the first patterned conductive layer512can be deposited on the exposed portions of the first transparent conductive layer506to create array516. In other embodiments, the first patterned conductive layer512may be deposited before the optically active layer508and the second transparent layer510. In such embodiments, the mask is overlaid on both the first transparent conductive layer506and the first patterned conductive layer512.

InFIG. 5, the array514is depicted as a rectilinear array, like electrochromic devices200and400. However, this depiction is not intended as limiting. The array514may include any pattern that defines three-dimensional cells across the optically active layer508. For example, the array can be a series of cells that can be rectilinear, triangular-shaped, diamond-shaped, pentagonal-shaped, hexagonal-shaped, octagonal-shaped, combinations thereof, or any other geometric shape.

In some embodiments, features of the array514are such that the patterned conductive layers512and522are not visible to the naked eye. For example, and without limitation, the array514may include conductive nanowires. In another non-limiting example, the array514may be formed using a conductive ink that, when hardened or dried, provides semi-transparency. The conductive ink can include a fluid having a transparent, conductive polymer dissolved therein. The conductive ink can also include metallic particles, which may be nanoparticles. Other features, however, are possible for the array514.

Like the previously described embodiments, o overcome sheet resistances, the patterned conductive layers512and522can have greater conductivity than the first and second transparent conductive layer506and510. This greater conductivity allows an electrical charge to use the patterned conductive layers512and522as an alternate, lower-resistance electrical conduit during operation. The electrical charge distributes through the patterned conductive layers512and522, and reaches areas throughout the transparent conductive layers506and510having lost minimal voltage potential. Moreover, the plurality of electrochromic cells516subdivides the electrochromic device500into smaller regions, allowing the optically active layer408to experience a more uniform voltage distribution (or distribution in voltage potential). Thus, by virtue of the patterned conductive layers512and522, the transmissive state can emerge more evenly throughout the optically active layer508, and switching times between transmissive states can be reduced.

In some embodiments, the electrochromic device500can further include a transparent layer (not shown), a portion of which forms an interface with the second patterned conductive layer522. The transparent layer can be bonded to the second patterned conductive layer522, the second transparent conductive layer510, or both. The transparent layer may be a superstrate body, such as a glass pane. The transparent layer may also be a coating, such as an epoxy coating, a thermoplastic coating, or other organic-based coatings.

In some embodiments, like electrochromic devices200and400, electrochromic device500can further include a power distribution circuit electrically coupled to the transparent conductive layers506and510and the patterned conductive layers512and522. In such embodiments, the power distribution circuit is configured to allow electrical power to selectively flow to individual cells in the plurality of electrochromic cells516. The power distribution circuit may have an electrical power source coupled thereto. In some embodiments, the power distribution circuit includes an electrical switch. In these embodiments, the electrical switch is configured to regulate electrical power flowing to the individual cells in the plurality of electrochromic cells516. This regulation may include selectively applying voltages to individual electrochromic cells516in order to produce patterns of transmissive states across the electrochromic device500. Non-limiting examples of patterns include gradients in shading, step-contrasts between shaded and non-shaded regions, and shading that defines informational characters (e.g., text). Other types of patterns of transmissive states are possible.

Although the illustrative embodiments describe the electrochromic devices as being incorporated into windows, the electrochromic device can be incorporated into other transparent panels. For example, by way of illustration without intending to be limiting, the electrochromic device can be incorporated in the glass covers for portable electronic devices or other devices.

According to an illustrative embodiment, a method of manufacturing an electrochromic device includes forming an optically active layer onto a first transparent conductive layer. The optically active layer is configured to alter optical properties in response to an applied electric field. The first transparent conductive layer is disposed on a portion of a transparent substrate. The method also includes depositing a second transparent conductive layer onto the optically active layer and patterning a conductive material into an array on the second transparent conductive layer. The array partitions the electrochromic device into a plurality of electrochromic cells. In some embodiments, the method further involves bonding a transparent superstrate to the array of patterned conductive material. In some embodiments, the optically active layer includes an electrochromic layer, an ion conductive layer, and an ion storage layer.

In some embodiments, patterning the conductive material into the array includes manipulating a precursor fluid onto the second transparent conductive layer using a process selected from the group consisting of rotogravure printing, ink-jet printing, screen-printing, and stamping.

In some embodiments, patterning the conductive material into the array can include coating a photoresist layer onto the second transparent conductive layer. The patterning the conductive material into the array can also include exposing a portion of the photoresist layer to an electromagnetic radiation. The portion corresponds to a configuration of the array. Patterning the conductive material into the array can also involve removing, after exposure to the electromagnetic radiation, the portion. Such removal can define an opening through the photoresist layer. The patterning the conductive material into the array additionally involves depositing the conductive material onto the second transparent conductive layer through the opening and removing an unexposed portion of the photoresist layer from the second transparent conductive layer. In further embodiments, exposing the portion of the photoresist layer can include receiving a beam of electromagnetic radiation from a laser writing system.