WO2024233252A1

WO2024233252A1 - Liquid crystal devices comprising a nematic liquid crystal mixture

Info

Publication number: WO2024233252A1
Application number: PCT/US2024/027403
Authority: WO
Inventors: Liang-Chy Chien; Mingqian He; Chien-Tsung Hou; Xiang-Dong Mi
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2023-05-05
Filing date: 2024-05-02
Publication date: 2024-11-14
Anticipated expiration: 2025-11-05

Abstract

Disclosed are liquid crystal devices Including a nematic liquid crystal mixture, a cell gap of at least 5 pm, a T_max ≥ 50%, and a T_min ≤ 10%. Also disclosed are liquid crystal windows incorporating said liquid crystal devices.

Description

Attorney Docket No. SP23-006PCT LIQUID CRYSTAL DEVICES COMPRISING A NEMATIC LIQUID CRYSTAL MIXTURE CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No.63/464,312 filed May 5, 2023, the content of which is incorporated herein by reference in its entirety. FIELD OF THE DISCLOSURE [0002] The disclosure relates generally to liquid crystal devices comprising a nematic liquid crystal mixture, and more particularly to liquid crystal windows comprising a cell gap of at least 5 ^m, a Tmax ^ 50%, and a Tmin ^ 10%. BACKGROUND [0003] Liquid crystal devices are used in various architectural and transportation applications, such as windows, doors, space partitions, and skylights for buildings and automobiles. For many commercial applications, it is desirable for liquid crystal devices to provide high contrast ratio between the on and off states while also providing good energy efficiency and cost effectiveness. For liquid crystal window applications, liquid crystal cells with larger cell gaps may be advantageous to improve lamination yields. However, such larger cell gaps can inhibit the performance of the window in terms of maximum transmittance (Tmax) when in the transparent state and minimum transmittance (Tmin) when in the dark state. Typically, it is desirable to have a Tmax ^ 50% and a Tmin ^ 10% for window performance, but these values are not attainable at higher liquid crystal cell gaps. [0004] As such, there is a need for liquid crystal devices with larger cell gaps that provide acceptable light transmission and light blocking. It would also be advantageous to improve the lamination yield and cost effectiveness for manufacturing such a liquid crystal device. It would further be advantageous to improve the energy efficiency of such a liquid crystal device. Attorney Docket No. SP23-006PCT SUMMARY [0005] Disclosed herein are liquid crystal devices comprising first and second glass substrate assemblies and a liquid crystal layer disposed therebetween comprising at least one nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye. Also disclosed herein are liquid crystal windows comprising a cell gap of at least 5 ^m, a Tmax ^ 50%, and a Tmin ^ 10%. [0006] The disclosure relates, in various embodiments, to liquid crystal devices comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal device is a normally dark liquid crystal device having a minimum light transmittance (Tmin) in the absence of voltage and a maximum light transmittance (Tmax) when voltage is applied, wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye, wherein the nematic liquid crystal comprises a birefringence (ǻ_n) and a positive dielectric anisotropy (ǻ_എ), ǻ_n < 0.11, and ¥(Ňǻ_എŇ)/ǻ_n > 30, wherein a twisting angle of the nematic liquid crystal ranges from 450 degrees to 2000 degrees in the absence of voltage, and wherein the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer, wherein the liquid crystal layer has a cell gap (d), and wherein (d*wt%) ranges from 20 to about 28 (^mÂ%). [0007] The disclosure also relates, in additional embodiments, to liquid crystal devices comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal device is a normally transparent liquid crystal device having a maximum light transmittance (Tmax) in the absence of voltage and a minimum light transmittance (T_min) when voltage is applied, wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye, wherein the nematic liquid crystal comprises a birefringence (ǻ_n) and a negative dielectric anisotropy (ǻ_എ), ǻ_n < 0.11, and ¥(Ňǻ_എŇ)/ǻ_n > 30, wherein a twisting angle of the nematic liquid crystal ranges from 225 degrees to 450 degrees when Attorney Docket No. SP23-006PCT voltage is applied, and wherein the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer, wherein the liquid crystal layer has a cell gap (d), and wherein (d*wt%) ranges from 28 to 32 (^mÂ%). [0008] In non-limiting embodiments, the first substrate assembly further comprises a first alignment layer, and the first electrode layer is disposed between the first glass substrate and the first alignment layer. In additional embodiments, the second substrate assembly further comprises a second alignment layer, and the second electrode layer is disposed between the second glass substrate and the second alignment layer. A cell gap (d) of the liquid crystal device can be at least about 5 μm in various embodiments, for example, ranging from about 5 ^m to about 10 μm, or from about 8 ^m to about 10 ^m. According to certain embodiments, Tmax is greater than or equal to 50% and Tmin is less than or equal to 10%. In further embodiments, ǻn < 0.1 and/or

/ǻn > 40. According to still embodiments, the liquid crystal layer also comprises at least one antioxidant. [0009] In still further embodiments, the liquid crystal devices also comprise: (d) a third substrate assembly comprising an interstitial substrate; and (e) a second liquid crystal layer; wherein the third substrate assembly is disposed between the first substrate assembly and the second substrate assembly, wherein the liquid crystal layer is disposed between the first substrate assembly and the third substrate assembly, and wherein the second liquid crystal layer is disposed between the third substrate assembly and the second substrate assembly. According to various embodiments, the third substrate assembly further comprises a third alignment layer and a fourth alignment layer, and the interstitial substrate is disposed between the third and fourth alignment layers. Additional embodiments include liquid crystal windows comprising the liquid crystal devices disclosed herein. [0010] Further disclosed herein are liquid crystal devices comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye; wherein the liquid crystal layer comprises a cell gap (d) ranging from about 5 ^m to about 10 ^m; and wherein the liquid crystal device comprises a Attorney Docket No. SP23-006PCT maximum light transmission (Tmax) greater than or equal to 50% and a minimum light transmission (Tmin) less than or equal to 10%. [0011] According to various embodiments, the first substrate assembly further comprises a first alignment layer, and the first electrode layer is disposed between the first glass substrate and the first alignment layer. In additional embodiments, the second substrate assembly further comprises a second alignment layer, and the second electrode layer is disposed between the second glass substrate and the second alignment layer. [0012] In certain embodiments, the liquid crystal device is a normally transparent liquid crystal device with T_max in the absence of voltage and T_min when voltage is applied. The nematic liquid crystal can comprise a negative dielectric anisotropy (ǻഎ). A total twisting angle of the nematic liquid crystal can range, in non- limiting embodiments, from 225 degrees to 450 degrees when voltage is applied. The at least one dichroic dye can have a concentration by weight (wt%) in the liquid crystal layer and, in various embodiments, (d*wt%) can range from 28 to 32 (^mÂ%). [0013] According to alternative embodiments, the liquid crystal device is a normally dark liquid crystal device with Tmin in the absence of voltage and Tmax when voltage is applied. The nematic liquid crystal can comprise a positive dielectric anisotropy (ǻഎ). A total twisting angle of the nematic liquid crystal can range, in non- limiting embodiments, from 450 degrees to 2000 degrees in the absence of voltage. The at least one dichroic dye can have a concentration by weight (wt%) in the liquid crystal layer and, in certain embodiments, (d*wt%) can range from about 20 to about 28 (^mÂ%). [0014] In non-limiting embodiments, the nematic liquid crystal can comprise a birefringence (ǻ_n) and a dielectric anisotropy (ǻ_എ), ǻ_n < 0.11, and /ǻn > 30. In additional embodiments, ǻn < 0.1 and/or

> 40. According to further embodiments, the liquid crystal layer can also comprise at least one antioxidant. [0015] Still further disclosed herein are liquid crystal devices comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one Attorney Docket No. SP23-006PCT black dichroic dye, wherein the liquid crystal layer comprises a cell gap (d) greater than or equal to 5 ^m, and wherein the nematic liquid crystal comprises a birefringence (ǻn) and a dielectric anisotropy (ǻഎ), ǻn < 0.11, and ¥(ŇǻഎŇ)/ǻn > 30. [0016] According to various embodiments, the liquid crystal device is a normally dark liquid crystal device having a minimum light transmittance (T_min) in the absence of voltage and a maximum light transmittance (T_max) when voltage is applied, and (i) a twisting angle of the nematic liquid crystal ranges from 450 degrees to 2000 degrees in the absence of voltage, (ii) the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer and (d*wt%) ranges from 20 to about 28 (^mÂ%), or (iii) both (i) and (ii). In alternative embodiments, the liquid crystal device is a normally transparent liquid crystal device having a maximum light transmittance (Tmax) in the absence of voltage and a minimum light transmittance (Tmin) when voltage is applied, and (i) a twisting angle of the nematic liquid crystal ranges from 225 degrees to 450 degrees when voltage is applied, (ii) the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer and (d*wt%) ranges from 28 to 32 (^mÂ%), or (iii) both (i) and (ii). In certain embodiments, Tmax ^ 50% and Tmin ^ 10%. [0017] In still further embodiments, the liquid crystal devices also comprise: (d) a third substrate assembly comprising an interstitial substrate; and (e) a second liquid crystal layer; wherein the third substrate assembly is disposed between the first substrate assembly and the second substrate assembly, wherein the liquid crystal layer is disposed between the first substrate assembly and the third substrate assembly, and wherein the second liquid crystal layer is disposed between the third substrate assembly and the second substrate assembly. According to various embodiments, the third substrate assembly further comprises a third alignment layer and a fourth alignment layer, and the interstitial substrate is disposed between the third and fourth alignment layers. Further embodiments include liquid crystal windows comprising the liquid crystal devices disclosed herein. [0018] Additional features and advantages of the disclosure will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings. Attorney Docket No. SP23-006PCT [0019] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary and are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure and together with the description serve to explain the principles and operations of the various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS [0020] The following detailed description can be further understood when read in conjunction with the following drawings. The drawings are provided for purposes of illustration only and merely depict exemplary embodiments of the present disclosure to facilitate the understanding of the present disclosure. Therefore, the drawings should not be considered as limiting of the breadth, scope, or applicability of the present disclosure. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. It is to be understood that the figures are not drawn to scale and the size of each depicted component or the relative size of one component to another is not intended to be limiting. [0021] FIG.1 depicts a cross-sectional view of a liquid crystal device according to one or more embodiments of the present disclosure; and [0022] FIG.2 depicts a cross-sectional view of another liquid crystal device according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION [0023] For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the disclosure is thereby intended. It is further understood that the present disclosure includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles disclosed herein as would normally occur to one skilled in the art to which this disclosure pertains. Attorney Docket No. SP23-006PCT [0024] As used herein, the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. [0025] In this document, relational terms, such as first and second, top and bottom, and the like, are used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. [0026] As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. When the term “about” is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to. Whether or not a numerical value or end-point of a range in the specification recites “about,” the numerical value or end-point of a range is intended to include two embodiments: one modified by “about,” and one not modified by “about.” It will be further understood that the end- points of each of the ranges are significant both in relation to the other end-point, and independently of the other end-point. [0027] Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub- ranges encompassed within that range as if each numerical value and sub-range was explicitly recited. As an illustration, a numerical range of “about 1 to about 5” should be interpreted to include not only the explicitly recited values of about 1 to about 5, but also to include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3, and 4, the sub ranges such as from 1-3, from 2-4, from 3-5, etc., as well as 1, 2, 3, 4, and 5 individually. The same principle applies to ranges reciting only one numerical value Attorney Docket No. SP23-006PCT as a minimum or maximum. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described by the range. [0028] The terms “substantial,” “substantially,” and variations thereof as used herein, unless defined elsewhere in association with specific terms or phrases, are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, “substantially” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially” may denote values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other. [0029] Directional terms as used herein—for example up, down, right, left, front, back, top, bottom, above, below, and the like—are made only with reference to the figures as drawn and are not intended to imply absolute orientation. [0030] As used herein the terms "the," "a," or "an," mean "at least one," and should not be limited to "only one" unless explicitly indicated to the contrary. Thus, for example, reference to "a component" includes embodiments having two or more such components unless the context clearly indicates otherwise. [0031] Disclosed herein are liquid crystal devices comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal device is a normally dark liquid crystal device having a minimum light transmittance (T_min) in the absence of voltage and a maximum light transmittance (T_max) when voltage is applied, wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye, wherein the nematic liquid crystal comprises a birefringence (ǻn) and a positive dielectric anisotropy (ǻഎ), ǻn < 0.11, and /ǻn > 30, wherein a twisting angle of the nematic liquid crystal ranges from 450 degrees to 2000 degrees in the absence of voltage, and wherein the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer, wherein the liquid crystal layer has a cell gap (d), and wherein (d*wt%) ranges from 20 to about 28 (^mÂ%). Attorney Docket No. SP23-006PCT [0032] Also disclosed herein are liquid crystal devices comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal device is a normally transparent liquid crystal device having a maximum light transmittance (T_max) in the absence of voltage and a minimum light transmittance (T_min) when voltage is applied, wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye, wherein the nematic liquid crystal comprises a birefringence (ǻ_n) and a negative dielectric anisotropy (ǻ_എ), ǻn <

/ǻn > 30, wherein a twisting angle of the nematic liquid crystal ranges from 225 degrees to 450 degrees when voltage is applied, and wherein the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer, wherein the liquid crystal layer has a cell gap (d), and wherein (d*wt%) ranges from 28 to 32 (^mÂ%). [0033] Further disclosed herein are liquid crystal devices comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye; wherein the liquid crystal layer comprises a cell gap (d) ranging from about 5 ^m to about 10 ^m; and wherein the liquid crystal device comprises a maximum light transmission (T_max) greater than or equal to 50% and a minimum light transmission (T_min) less than or equal to 10%. [0034] Still further disclosed herein are liquid crystal devices comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye, wherein the liquid crystal layer comprises a cell gap (d) greater than or equal to 5 ^m, and wherein the nematic liquid crystal comprises a ^{birefringence (ǻ} _{n) and a dielectric anisotropy (ǻഎ), ǻn < 0.11, and ¥}

_{/ǻn > 30.} Attorney Docket No. SP23-006PCT [0035] Embodiments of the disclosure will now be discussed with reference to FIGS.1-2, which illustrate various aspects of the disclosure. The following general description is intended to provide an overview of the claimed devices, and various aspects will be more specifically discussed throughout the disclosure with reference to the non-limiting depicted embodiments, these embodiments being interchangeable with one another within the context of the disclosure. [0036] FIGS.1-2 illustrate cross-sectional views of non-limiting embodiments of liquid crystal devices 100 (FIG.1) and 200 (FIG.2). The liquid crystal devices disclosed herein may have a single cell configuration, e.g., a single liquid crystal unit controlled by a single pair of electrodes. The liquid crystal unit may comprise a single liquid crystal layer, as depicted in FIG.1, two liquid crystal layers, as depicted in FIG.2, or more than two liquid crystal layers (not depicted). [0037] Referring to FIG.1, liquid crystal device 100 includes first and second substrate assemblies 100A, 100B. First substrate assembly 100A comprises a first glass substrate 101 having a first surface 101A and a second surface 101B. A first electrode layer 103 is formed on and/or in direct contact with second surface 101B of first glass substrate 101. The first substrate assembly 100A can, in some embodiments, further include a first alignment layer 106. The first alignment layer 106 is formed on and/or in direct contact with the first electrode layer 103. The first electrode layer 103 is thus disposed between the first glass substrate 101 and the first alignment layer 106 (if present), as depicted in FIG.1. According to various embodiments, no additional layers are present between the first electrode layer 103 and the first substrate 101 or between the first electrode layer 103 and the first alignment layer 106. In further embodiments, the first substrate assembly 100A consists of the first substrate 101, the first electrode 103, and the first alignment layer 106. The first substrate assembly 100A may be referred to interchangeably herein as an “outer” substrate assembly and the first glass substrate 101 may be referred to herein as an “outer” substrate. [0038] Similarly, second substrate assembly 100B comprises a second glass substrate 102 having a first surface 102A and a second surface 102B. A second electrode layer 104 is formed on and/or in direct contact with first surface 102A of second glass substrate 102. The second substrate assembly 100B can, in some embodiments, further include a second alignment layer 107. The second Attorney Docket No. SP23-006PCT alignment layer 109 is formed on and/or in direct contact with the second electrode layer 104. The second electrode layer 104 is thus disposed between the second glass substrate 102 and the second alignment layer 107 (if present), as depicted in FIG.1. According to various embodiments, no additional layers are present between the second electrode layer 104 and the second substrate 102 or between the second electrode layer 104 and the second alignment layer 109. In further embodiments, the second substrate assembly 100B consists of the second substrate 102, the second electrode 104, and the second alignment layer 107. The second substrate assembly 100B may be referred to interchangeably herein as an “outer” substrate assembly and the second glass substrate 102 may be referred to herein as an “outer” substrate. [0039] Liquid crystal device 100 further includes liquid crystal layer 110, which is disposed between the first and second substrate assemblies 100A, 100B. As depicted in FIG.1, liquid crystal layer 110 may be in direct contact with the first alignment layer 106 of the first substrate assembly 100A and the second alignment layer 107 of the second substrate assembly 100B. According to various embodiments, no additional layers are present between the liquid crystal layer 110 and the first alignment layer 106 or between the first liquid crystal layer 110 and the second alignment layer 107. In non-limiting embodiments, first alignment layer 106 and/or second alignment layer 107 may not be present. In such embodiments, liquid crystal layer 110 may be in direct contact with first electrode layer 103 and/or second electrode layer 104. According to still further embodiments, the liquid crystal device may consist of the first substrate assembly 100A, the second substrate assembly 100B, and liquid crystal layer 110. [0040] First substrate assembly 100A can be produced, for example, by coating, printing, or otherwise depositing the first electrode layer 103 on the second surface 101B of the first substrate 101, and coating, printing, or otherwise depositing the first alignment layer 106 on the first electrode layer 103. Similarly, second substrate assembly 100B can be produced by coating, printing, or otherwise depositing the second electrode layer 104 on the first surface 102A of the second substrate 102, and coating, printing, or otherwise depositing the second alignment layer 107 on the second electrode layer 104. These substrates assemblies can then be arranged to form a gap, which can be filled with liquid crystal material to form liquid crystal layer 110. In some embodiments, spacers (not illustrate) can be used Attorney Docket No. SP23-006PCT to maintain the desired cell gap and resulting liquid crystal layer thickness. The liquid crystal material can be sealed in the cell gaps around all edges using any suitable material, such as optically or thermally curable resins, to form first seal s1. [0041] According to non-limiting embodiments, liquid crystal device 100 can include at least one interdigitated electrode. Interdigitated electrode layers comprise a pair of electrodes on a single surface that are energized with different voltages. Referring to FIG.1, first electrode layer 103 can comprise an interdigitated electrode pair formed on second surface 101B of first substrate 101, and second electrode layer 104 may not be present. Alternatively, second electrode layer 104 can comprise an interdigitated electrode pair formed on first surface 102A of second substrate 102, and first electrode layer 103 may not be present. [0042] As shown in FIG.2, the liquid crystal devices disclosed herein can include more than one liquid crystal layer. For example, liquid crystal device 200 comprises a third substrate assembly 100C, disposed between the first and second substrate assemblies 100A, 100B. As depicted in FIG.2, third substrate assembly 100C comprises a third alignment layer 108, a fourth alignment layer 109, and an interstitial substrate 105. The third and fourth alignment layers 107, 108, if present, can be formed on and/or in direct contact with opposing surfaces of the interstitial substrate 105. The third substrate 105 is thus disposed between the third alignment layer 108 and the fourth alignment layer 109, as depicted in FIG.2. According to non-limiting embodiments, the third substrate assembly can comprise the interstitial substrate 105 in the absence of alignment layers. In other embodiments, the third substrate assembly can comprise the interstitial substrate 105 and only one of alignment layers 108 or 109. In further embodiments, the third substrate assembly 100C consists of the third substrate 103, the third alignment layer 107, and the fourth alignment layer 108. The third substrate 105 may comprise glass, similar to the first and second substrates 101, 102, or may comprise any other suitable material, such as ceramics or plastics. The third substrate assembly 100C may be referred to interchangeably herein as an “interstitial” substrate assembly and the interstitial substrate 105 may be referred to herein as a “third” substrate. [0043] Liquid crystal device 200 further includes a second liquid crystal layer 111, which is disposed between the second and third substrate assemblies 100B, 100C. Liquid crystal layer 110, which may also be referred to herein as “first” liquid crystal layer, is disposed between the first and third substrate assemblies Attorney Docket No. SP23-006PCT 100A, 100C. First liquid crystal layer 110 may be in direct contact with the first alignment layer 106 of the first substrate assembly 100A and in direct contact with the third alignment layer 108 of the third substrate assembly 100C, if these alignment layers are present. According to various embodiments, no additional layers are present between the first liquid crystal layer 110 and the first alignment layer 106 or between the first liquid crystal layer 110 and the third alignment layer 108. Similarly, second liquid crystal layer 111 may be in direct contact with the second alignment layer 107 of the second substrate assembly 100B and in direct contact with the fourth alignment layer 109 of the third substrate assembly 100C, if these alignment layers are present. In certain embodiments, no additional layers are present between the second liquid crystal layer 111 and the second alignment layer 107 or between the second liquid crystal layer 111 and the fourth alignment layer 109. According to further embodiments, the liquid crystal device may consist of the first substrate assembly 100A, the second substrate assembly 100B, the third substrate assembly 100C, the first liquid crystal layer 110 and the second liquid crystal layer 111. [0044] First substrate assembly 100A can be produced, for example, by coating, printing, or otherwise depositing the first electrode layer 103 on the second surface 101B of the first substrate 101, and coating, printing, or otherwise depositing the first alignment layer 106 on the first electrode layer 103. Similarly, second substrate assembly 100B can be produced by coating, printing, or otherwise depositing the second electrode layer 104 on the first surface 102A of the second substrate 102, and coating, printing, or otherwise depositing the second alignment layer 107 on the second electrode layer 104. Third substrate assembly 100C can be produced by coating, printing, or otherwise depositing the third and fourth alignment layers 108, 109 on opposing surfaces of the interstitial substrate 105. These substrates assemblies can then be arranged, with the third substrate assembly 100C between the first and second substrate assemblies 100A and 100C, to form two gaps, which can be filled with liquid crystal material to form liquid crystal layers 110, 111. In some embodiments, spacers (not illustrated) can be used to maintain the desired cell gap and resulting liquid crystal layer thickness. The liquid crystal material can be sealed in the cell gaps around all edges using any suitable material, such as optically or thermally curable resins, to form first seals s1 and second seals s2. Attorney Docket No. SP23-006PCT [0045] It is to be understood that the scope of the disclosure is not limited solely to the embodiments depicted in FIGS.1-2. The liquid crystal devices disclosed herein can comprise additional liquid crystal layers and additional substrate assemblies with different configurations. Various components of liquid crystal devices 100 and 200 will now be discussed in more detail. Materials Substrates [0046] The following description is intended to apply to any substrates used in the liquid crystal devices disclosed herein, including those discussed above with reference to FIGS.1-2, e.g., the first, second, and/or interstitial substrates 101, 102, 105, and any other additional substrates, if present. The characteristics and properties of each substrate can be independently selected and can be the same or different from other substrates in the liquid crystal window. [0047] According to non-limiting embodiments, at least one of the substrates in the liquid crystal window can comprise an optically transparent material. As used herein, the term “optically transparent” is intended to denote that the component and/or layer has a transmission of greater than about 80% in the visible region of the spectrum (~400-700nm). For instance, an exemplary component or layer may have greater than about 85% transmittance in the visible light range, such as greater than about 90%, or greater than about 92%, including all ranges and subranges therebetween. In certain embodiments, all of the substrates in the liquid crystal window can comprise an optically transparent material. [0048] Visible light transmittance, also understood as luminous transmittance, is defined as the percent of transmitted light, per American Society for Testing and Materials (ASTM) D1003 “Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics.” The terms “transmittance,” “luminous transmittance,” “visible light transmittance,” and similarly worded terms are used interchangeably herein and are intended to have the same meaning, unless clearly contracted by context (e.g., transmittance relating specifically to UV and/or IR). Visible light transmittance is a fraction of the visible spectrum of standard illuminant D65 sunlight (380 to 720 nanometers) through an optical component such as a window, weighted by the sensitivity of the human eye. The visible light transmittance can be measured by various haze meters such as BYK-Gardner’s Attorney Docket No. SP23-006PCT Haze-Gard. As used herein, the haze and transmittance of a liquid crystal cell refers to the haze and transmittance as measured through the first and second electrodes, first and second orientation layers (if both are present), a liquid crystal layer, first and second substrates (if one or both are present), and one or more polarizers (if present). Generally, transmittance as disclosed herein does not include transmittance through interlayers, insulating gases, third and fourth substrates, UV/IR layers, and so forth. [0049] According to various embodiments, all or some of the substrates in the liquid crystal window can comprise glass sheets. The substrates can have any shape and/or size, such as a rectangle, square, or any other suitable shape, including regular and irregular shapes and shapes with one or more curvilinear edges. According to various embodiments, the substrates can have a thickness of less than or equal to about 4 mm, for example, ranging from about 0.1 mm to about 4 mm, from about 0.2 mm to about 3 mm, from about 0.3 mm to about 2 mm, from about 0.5 mm to about 1.5 mm, or from about 0.7 mm to about 1 mm, including all ranges and subranges therebetween. In certain embodiments, the substrates can have a thickness of less than or equal to 0.5 mm, such as 0.4 mm, 0.3 mm, 0.2 mm, 0.1 mm, 0.05 mm, or 0.01 mm, including all ranges and subranges therebetween. In non-limiting embodiments, the substrates can have a thickness ranging from about 1 mm to about 3 mm, such as from about 1.5 to about 2 mm, including all ranges and subranges therebetween. The substrates in the liquid crystal window may, in some embodiments, comprise the same thickness, or may have different thicknesses. [0050] In various embodiments, the substrates can comprise any glass known in the art, for example, soda-lime silicate, aluminosilicate, alkali- aluminosilicate, borosilicate, alkaliborosilicate, aluminoborosilicate, alkali- aluminoborosilicate, and other suitable display glasses. The substrates may, in some embodiments, comprise the same glass, or may comprise different glasses. The glass substrates may, in various embodiments, be chemically strengthened and/or thermally tempered. Non-limiting examples of suitable commercially available glasses include EAGLE XG^®, Lotus^TM, Willow^®, and Gorilla^® glasses from Corning Incorporated, to name a few. Chemically strengthened glass, for example, may be provided in accordance with U.S. Patent Nos.7,666,511, 4,483,700, and 5,674,790, which are incorporated herein by reference in their entireties. Attorney Docket No. SP23-006PCT [0051] According to additional embodiments, one or more of the substrates can comprise a low emissivity or Low-E glass. Low-E glasses have a coating that can minimize the amount of infrared (IR) and/or ultraviolet (UV) light that passes through the glass. The UV and/or IR transmittance of a Low-E glass can be less than about 5%, such as less than 2%, less than 1%, less than 0.5%, or less than 0.1%, including all ranges and subranges therebetween. The Low-E glass can minimize UV and/or IR light transmission without impacting the transmission of visible light through the glass. When Low-E glass is included in the liquid crystal window, it may be oriented to face the exterior, e.g., the outside of a building or vehicle, to protect the liquid crystal window from undesired incoming radiation. [0052] According to various embodiments, the glass substrates may be chosen from glass sheets produced by a fusion draw process. Without wishing to be bound by theory, it is believed that the fusion draw process can provide glass sheets with a relatively low degree of waviness (or high degree of flatness), which may be beneficial for various liquid crystal applications. An exemplary glass substrate may thus, in certain embodiments, comprise a surface waviness of less than about 100 nm as measured with a contact profilometer, such as about 80 nm or less, about 50 nm or less, about 40 nm or less, or about 30 nm or less, including all ranges and subranges therebetween. An exemplary standard technique for measuring waviness (0.8~8mm) with a contact profilometer is outlined in SEMI D15-1296 “FPD Glass Substrate Surface Waviness Measurement Method.” With reference to FIGS.1-2, at least one of the first and second surfaces 101A, 101B of first glass substrate 101 and/or at least one of the first and second surfaces 102A, 102B of second glass substrates 102 can, in some embodiments, comprise a surface waviness as described above, e.g., of less than about 100 nm. Similarly, at least one of the surfaces of the interstitial substrate 105 can, in non-limiting embodiments, also comprise a surface waviness of less than about 100 nm. [0053] The interstitial substrate 105, if present, as well as any other interstitial substrates that might be present in the liquid crystal window, can comprise a glass material as discussed above. According to other embodiments, the interstitial substrate(s) may comprise a material other than glass, such as plastics. Suitable plastic materials include, but are not limited to, polycarbonates, polyacrylates such as polymethylmethacrylate (PMMA), and polyethyelenes such as polyethylene terephthalate (PET). Attorney Docket No. SP23-006PCT Electrodes [0054] The liquid crystal windows disclosed herein can comprise at least one electrode pair, e.g., first and second electrodes 103, 104. Additional electrodes may be present depending on the window configuration and the number of switchable layers. The characteristics and properties of each electrode can be independently selected and can be the same or different from other electrodes in the liquid crystal window. [0055] Electrode layers in the liquid crystal window may comprise one or more transparent conductive oxides (TCOs), such as indium tin oxide (ITO), indium zinc oxide (IZO), gallium zinc oxide (GZO), aluminum zinc oxide (AZO), and other like materials. Alternatively, the electrode layers may comprise other transparent materials, such as a conductive mesh, e.g., comprising metals such as silver nanowires or other nanomaterials such as graphene or carbon nanotubes, or polymers doped with conductive nanowires or nanomaterials. Printable conductive ink layers such as ActiveGrid^TM from C3Nano Inc. may also be used. According to various embodiments, the surface conductance of the electrode layers can range from about 10 ȍ/Ƒ (ohms/square) to about 1000 ȍ/Ƒ, such as from about 50 ȍ/Ƒ to about 900 ȍ/Ƒ, from about 100 ȍ/Ƒ to about 800 ȍ/Ƒ, from about 200 ȍ/Ƒ to about 700 ȍ/Ƒ, from about 300 ȍ/Ƒ to about 600 ȍ/Ƒ, or from about 400 ȍ/Ƒ to about 500 ȍ/Ƒ, including all ranges and subranges therebetween. In certain embodiments, the surface conductance of the electrode layers can be less than or equal to about 100 ȍ/Ƒ. [0056] Electrodes can be fabricated using any technique known in the art, such as vacuum sputtering, film lamination, or printing techniques. Electrodes can be deposited on one or more substrate surfaces to form a layer of material that may or may not comprise a pattern. The thickness of each electrode layer can, for example, independently range from about 1 nm to about 1000 nm such as from about 5 nm to about 500 nm, from about 10 nm to about 300 nm, from about 20 nm to about 200 nm, from about 30 nm to about 150 nm, or from about 50 nm to about 100 nm, including all ranges and subranges therebetween. [0057] In non-limiting embodiments, the electrode layers 103, 104 can comprise a pattern, such that they produce desired zones or pixels to allow the switching of the entire liquid crystal device or only a desired portion of the device. Attorney Docket No. SP23-006PCT For instance, the electrode layers can be patterned to form a plurality of lines or stripes having a vertical or horizontal orientation. Such a pattern can be used to configure, e.g., window transmission similar to mechanical shades by turning on alternating stripes or by setting adjacent electrode stripes to different transmission intensities. Alternative patterns are possible and envisioned as falling within the scope of this disclosure, such as a matrix of square or rectangular pixels, which can be used to configure, e.g., window transmission to provide an arbitrary pattern. The width of the patterned lines and/or pixels can range, in various embodiments, from about 1 mm to about 500 mm, such as from about 2 mm to about 400 mm, from about 3 mm to about 300 mm, from about 5 mm to about 200 mm, from about 10 mm to about 100 mm, or from about 20 mm to about 50 mm, including all ranges and subranges therebetween. Liquid Crystal Layers [0058] Liquid crystal device disclosed herein can include at least one liquid crystal layer, such as liquid crystal layer 110 and/or second liquid crystal layer 120, as well as any other additional liquid crystal layers that might be present in the device. The characteristics and properties of each liquid crystal layer can be independently selected and can be the same or different from other liquid crystal layers in the liquid crystal device. [0059] According to various embodiments, the liquid crystal layer(s) in the window disclosed herein can comprise a cell gap or cavity filled with liquid crystal material. The thickness of the liquid crystal layer, or the cell gap distance, can be maintained by particle spacers and/or columnar spacers dispersed in the liquid crystal layer. The liquid crystal layers can have a thickness or cell gap of greater than or equal to about 5 ^m, for example, ranging from about 5 ^m to about 20 ^m, from about 8 ^m to about 15 ^m, or from about 10 ^m to about 12 ^m, including all ranges and subranges therebetween. If more than one liquid crystal layer is present in the window, these layers may comprise the same thickness or may have different thicknesses, e.g., each liquid crystal layer can have a cell gap of greater than or equal to about 5 ^m. [0060] According to non-limiting embodiments, the liquid crystal layers can comprise a nematic liquid crystal material having positive or negative dielectric anisotropy ('H). Non-limiting examples of commercially available nematic liquid Attorney Docket No. SP23-006PCT crystals with positive dielectric anisotropy are TMS83700 from Merck ('H = +10.6, ǻ_n = 0.1 @ 589 nm, 20^oC), KH-8109-000 from GrandinChem Co. Ltd ('H = +15.8, ǻn = 0.091 @ 589 nm, 20^oC), and DB8000-000 from GrandinChem Co. ('H = +15.1, ǻ_n = 0.0.091 @ 589 nm, 20^oC). Commercially available nematic liquid crystals with negative dielectric anisotropy include, but are not limited to, ZLI-2806 from Merck ('H = -4.8, ǻ_n = 0.044 @ 589 nm, 20^oC). [0061] According to various embodiments, the birefringence ²_n of the nematic liquid crystal may be less than 0.11, such as ranging from about 0.01 to about 0.1, from about 0.02 to about 0.09, from about 0.03 to about 0.08, from about 0.04 to about 0.07, or from about 0.05 to about 0.06, including all ranges and subranges therebetween, as measured at 589 nm and 20^oC. In some non-limiting embodiments, ²n < 0.1. According to certain embodiments, the nematic liquid crystal may satisfy the equation ¥(Ňǻ_എŇ)/ǻ_n > 30 or, in further embodiments,

> 40. Stated otherwise, the square root of the absolute value of ǻ_എ divided by ǻ_n is greater than 30, such as greater than 35 or greater than 40. Alignment Layers [0062] Specific alignment of a liquid crystal layer can, in some embodiments, be improved by coating one or more surfaces of the substrates and/or electrodes with an alignment layer, for example, alignment layers 106, 107, 108, 109 as shown in FIGS.1-2. Alignment layers can comprise a thin film of material having a surface energy and anisotropy promoting the desired orientation, for the liquid crystals in direct contact with its surface. [0063] The orientation of liquid crystal material can be described by a unit vector, referred to herein as a “director,” which represents the average local orientation of the long molecular axes of the liquid crystal molecules. The substrates in the liquid crystal device can have a surface energy promoting the desired alignment of the liquid crystal director in a ground or “off” state without applied voltage. A vertical or homeotropic alignment is achieved when the liquid crystal director has a perpendicular or substantially perpendicular orientation with respect to the plane of the substrate. A planar or homogeneous alignment is achieved when the liquid crystal director has a parallel or substantially parallel orientation with respect to the plane of the substrate. An oblique alignment is achieved when the liquid crystal direction has a large angle with respect to the plane of the substrate, Attorney Docket No. SP23-006PCT which is substantially different from planar or homeotropic, i.e., ranging from about 20^o to about 70^o, such as from about 30^o to about 60^o, or from about 40^o to about 50^o, including all ranges and subranges therebetween. [0064] Exemplary materials for use in the alignment layers can include, but are not limited to, main chain or side chain polyimides, which can be mechanically rubbed to generate layer anisotropy; photosensitive polymers, such as azobenzene- based compounds, which can be exposed to linearly polarized light to generate surface anisotropy; and inorganic thin films, such as silica, which can be deposited using thermal evaporating techniques to form periodic microstructures on the surface. Organic alignment layers promoting vertical or homeotropic orientation of the liquid crystal molecules may be rubbed to create different pretilt angles other than 90^o with respect to the plane of the substrate. The pretilt angle of the liquid crystal molecules with respect to the substrate surface will break the symmetry during switching from vertical orientation and can define an azimuthal direction of liquid crystal switching. [0065] Organic alignment layers may be deposited, for example, by spincoating a solution onto a desired surface or using printing techniques. Inorganic alignment layers can be deposited using thermal evaporation techniques. According to various embodiments, the first, second, third, and fourth alignment layers 106, 107, 108, 109, if present, and any additional alignment layers, can have a thickness of less than or equal to about 100 nm, for example, ranging from about 1 nm to about 100 nm, from about 5 nm to about 90 nm, from about 10 nm to about 80 nm, from about 20 nm to about 70 nm, from about 30 nm to about 60 nm, or from about 40 nm to about 50 nm, including all ranges and subranges therebetween. The alignment layers 106, 107, 108, 109, and any other additional alignment layers may, in some embodiments, comprise the same thickness, or may have different thicknesses. [0066] While improved alignment of the liquid crystals can be attained through the use of alignment layers, such alignment layers are not required components for the liquid crystal devices disclosed herein. While FIGS.1-2 depict alignment layers in contact with both sides of liquid crystal layers 110 and 111, it is possible to remove one or more of the alignment layers such that no alignment layers are in contact with the liquid crystal layer(s) or only one alignment layer is in contact with the liquid crystal layer. As such, referring to FIG.1, one or more of Attorney Docket No. SP23-006PCT alignment layers 106 or 107 may be removed from device 100 without departing from the scope of the disclosure. First substrate assembly 100A can comprise or consist of first substrate 101 and first electrode 103, i.e., without the presence of first alignment layer 106. Similarly, second substrate assembly 100B can comprise or consist of second substrate 102 and second electrode 104. One or more of alignment layers 106, 107, 108, and 109 can likewise be removed from device 200 depicted in FIG.2. Dichroic Dyes [0067] In some embodiments, dyes or other coloring agents, such as dichroic dyes, can be added to one or more of the liquid crystal layers 110, 111 to absorb light transmitted through the liquid crystal layer(s). Dichroic dyes typically absorb light more strongly along a direction parallel to the direction of a transition dipole moment in the dye molecule, which is typically the longer molecular axis of the dye molecule. Dye molecules oriented with their long axis perpendicular to the direction of light polarization will provide low light attenuation, whereas dye molecules oriented with their long axis parallel to the direction of light polarization will provide strong light attenuation. Non-limiting examples of dichroic dyes include, for example, black dichroic dyes such as azo or anthraquinone dyes. Commercially available black dichroic dyes include, but are not limited to, S-428 and M-1012 available from Mitsui Fine Chemicals, Inc. [0068] A normally transparent (or bright/clear) liquid crystal (NT LC) device with the maximum light transmission in the “off” state can, in various embodiments, be achieved by using a homeotropic (vertical) alignment and a liquid crystal layer comprising nematic liquid crystals with negative dielectric anisotropy and additive dye molecules. In this configuration, the dye molecules will be aligned in a low- absorbing perpendicular orientation in the powered “off” state and will be rotated with the liquid crystals to a highly-absorbing parallel orientation in the powered “on” state. Similarly, a normally dark (or opaque) liquid crystal (ND LC) device with the maximum light transmission in the “on” state can, in certain embodiments, be achieved by using a homogeneous (planar) alignment and a liquid crystal layer comprising nematic liquid crystals with positive dielectric anisotropy and additive dye molecules. In this configuration, the dye molecules will be aligned in a highly- Attorney Docket No. SP23-006PCT absorbing parallel orientation in the powered “off” state and will be rotated with the liquid crystals to a low-absorbing perpendicular orientation in the powered “on” state. [0069] According to various embodiments, the amount of dichroic dye present in the liquid crystal mixture can vary, for example, from about 2 wt% to about 10 wt%, such as from about 3 wt% to about 8 wt%, from about 4 wt% to about 7 wt%, or from about 5 wt% to about 6 wt%, including all ranges and subranges therebetween. The concentration of dichroic dye in the liquid crystal mixture can, in certain embodiments, be chosen relative to the cell gap of the liquid crystal layer. For instance, cell gap (d) x dye concentration (wt%) can be greater than 20 (^mÂ%). According to non-limiting embodiments, (d*wt%) can range from about 20 to about 34, such as from about 22 to about 32, from about 24 to about 30, or from about 26 to about 28. For a normally dark liquid crystal device, (d*wt%) can range from about 20 to about 28 (^mÂ%), whereas for a normally transparent liquid crystal device, (d*wt%) might range from about 28 to about 34 (^mÂ%), according to various embodiments. [0070] In some embodiments, the dichroic dye can have an average dichroic ratio greater than about 5, such as greater than about 8, greater than about 10, greater than about 12, greater than about 15, greater than about 20, or higher, including all ranges and subranges therebetween. The average dichroic ratio of a dye can be provided in the literature supplied by the manufacturer or can be measured, for instance, as provided in Example 4 below. Chiral Dopants [0071] One or more chiral dopants may be added to the liquid crystal mixture to achieve a twisted supramolecular structure of liquid crystal molecules, referred to herein as cholesteric liquid crystal (CLC). The amount of twist in the CLC (or twist angle) is described by a helical pitch which represents the rotation angle of a local liquid crystal director by 360 degrees across the cell gap thickness. CLC twist can also be quantified by a ratio (d/p) of cell gap thickness (d) to CLC helical pitch (p). For liquid crystal applications, the amount of chiral dopant dissolved in the liquid crystal mixture as well as the helical twisting power of the chiral dopant can be modified to achieve a desired amount of twist across a given cell gap distance. It is within the ability of one skilled in the art to select the appropriate dopant and its amount to achieve the desired twisted effect. Attorney Docket No. SP23-006PCT [0072] In the case of planar or homogeneous alignment, in the “off” state a twisted CLC structure will align the dye molecules in a parallel or horizontal orientation, thereby creating a dark/opaque state with minimum light transmission. In the “on” state, the liquid crystal layer will be realigned by the applied electric field to a perpendicular or vertical orientation, thereby creating a transparent/bright/clear state with maximum light transmission. Similarly, in the case of vertical or homeotropic alignment, in the “off” state a twisted CLC structure will be suppressed by the alignment layers on either side of the liquid crystal layer, which causes the dye molecules to align in a perpendicular/vertical orientation, thereby creating a transparent/bright/clear state with maximum light transmission. In the “on” state, the liquid crystal layer will be realigned by the applied electric field to a parallel/horizontal orientation, thereby creating a dark/opaque state with minimum light transmission. [0073] In various embodiments, the liquid crystal layers disclosed herein may have a twist angle ranging from about 0.5x360^o (=180^o) to about 10x360^o (=3600^o) (or d/p ranging from about 0.5 to about 10), for example, ranging from about 360^o to about 1800^o (d/p from about 1 to about 5), from about 540^o to about 1440^o (d/p from about 1.5 to about 4), or from about 720^o to about 1080^o (d/p from about 2 to about 3), including all ranges and subranges therebetween. For a normally dark liquid crystal device, the twist angle can range from about 450^o to about 2000^o, whereas for a normally transparent liquid crystal device, the twist angle might range from about 225^o to about 450^o, according to various embodiments. Non-limiting examples of commercially available chiral dopants include, for example, S811, R811, S1011, R1011, S5011, R5011, and CB15, all available from Merck. [0074] Operation of the liquid crystal windows disclosed herein can comprise switching the windows from one state to another, e.g., switching a ND LC from the dark state to the transparent state and back, or switching a NT LC from the transparent state to the dark state and back. Switching between states can be achieved by applying voltage to electrodes in electrical contact with the liquid crystal layer(s). The voltage can, for example, be greater than about 1 volt, such as greater than about 2 volts, greater than about 5 volts, greater than about 10 volts, greater than about 20 volts, or greater than about 24 volts, including all ranges and subranges therebetween, e.g., ranging from about 1 volts to about 24 volts. In a typical display application, the voltage is less than 5 volts to accommodate thin film transistor (TFT) operation. However, in the liquid crystal window application, higher Attorney Docket No. SP23-006PCT voltage can be used and is believed to improve transmittance in the transparent state or reduce transmittance in the dark state. [0075] Voltage can be applied to the electrodes as a pulse having a time period or pulse width ranging from about 1 millisecond to about 200 milliseconds, such as from about 5 milliseconds to about 150 milliseconds, from about 10 milliseconds to about 100 milliseconds, or from about 20 milliseconds to about 50 milliseconds. According to various embodiments, the response time of the LC, as defined by the time it takes to transition from one voltage state (e.g., V = 0) to another voltage state (e.g., V ^ 0), and vice versa, is greater than about 20 milliseconds, greater than about 100 milliseconds, or greater than about 200 milliseconds . [0076] The liquid crystal devices disclosed herein can be used in various architectural and transportation applications. For example, the liquid crystal devices can be used as liquid crystal windows that can be included in doors, space partitions, skylights, and windows for buildings, automobiles, and other transportation vehicles such as trains, planes, boats, and the like. [0077] The liquid crystal devices and windows disclosed herein may have various advantages as compared to prior art devices. For instance, the liquid crystal devices disclosed herein may have a higher cell gap, e.g., greater than or equal to 5 ^m, while still providing high maximum light transmission and low minimum light transmission values. Minimum light transmission in the dark/opaque state may be about 10% or less, such as about 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5% or less, including all ranges or subranges therebetween, while light transmission in the transparent/bright/clear state may be about 50% or greater, such as about 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 62% 64%, 66%, 68%, 70% or greater, including all ranges and subranges therebetween. Additionally, because of the larger cell gap between substrates, lamination yields during manufacturing may be improved, thereby lowering overall manufacturing costs and/or complexity. EXAMPLES [0078] The following examples illustrate non-limiting embodiments of the disclosure and are not intended to be limiting on the scope of the disclosure or claims. Attorney Docket No. SP23-006PCT Example 1 [0079] Normally dark liquid crystal (ND LC) devices were produced by assembling two glass substrates, each coated with an electrode layer and a planar alignment layer (PI-2170 from Nissan Chemical), which was rubbed ten times. A gap between the two glass substrate assemblies was filled with different nematic liquid crystals (TMS83700 from Merck, KH-8109-000 from GrandinChem Co., Ltd., or DB8000-000 from GrandinChem Co., Ltd.). The liquid crystal layer also included a black dichroic dye (M-1012 from Mitsui Fine Chemicals) and a chiral dopant (S811 from Merck). The cell gap (d) and dye concentration (wt%) were varied. The chiral dopant concentration was also varied to produce different twist angles. [0080] Varying voltages were applied across the electrodes and the maximum light transmission (T_max) and minimum light transmission (T_min) were measured for each liquid crystal device. The liquid crystal device configurations and measurement results are listed in Table I below, wherein “C” indicates a comparative example, which did not satisfy (T_max ^ 50% and T_min ^ 10%), and “I” indicates an inventive example. Table I: ND LC Devices

Attorney Docket No. SP23-006PCT

Example 2 [0081] Normally transparent liquid crystal (NT LC) devices were produced by assembling two glass substrates, each coated with an electrode layer and a vertical alignment layer (PI-5661 from Nissan Chemical), which was rubbed two times. A gap between the two glass substrate assemblies was filled with a nematic liquid crystal having negative dielectric anisotropy (ZLI-2806 from Merck). The liquid crystal layer also included a black dichroic dye (M-1012 from Mitsui Fine Chemicals) and a chiral dopant (S811 from Merck). The cell gap (d) and dye concentration (wt%) were varied. The chiral dopant concentration was also varied to produce different twist angles. [0082] A voltage of 24 V was applied across the electrodes and the maximum light transmission (Tmax) and minimum light transmission (Tmin) were measured for each liquid crystal device. The liquid crystal device configurations and measurement results are listed in Table II below, wherein “C” indicates a comparative example, which did not satisfy (Tmax ^ 50% and Tmin ^ 10%), and “I” indicates an inventive example. Table II: NT LC Devices

Attorney Docket No. SP23-006PCT

Example 3 [0083] Normally dark liquid crystal (ND LC) devices were produced in a method similar to that of Example 1. A cell gap of 9.7 ^m was filled with a nematic liquid crystal (KH-8109-000 from GrandinChem Co., Ltd.). The liquid crystal layer Attorney Docket No. SP23-006PCT also included 2.5 wt% of a black dichroic dye (M-1012 from Mitsui Fine Chemicals) and a chiral dopant (S811 from Merck) in a concentration sufficient to produce a twist angle of 1800 degrees. Antioxidants were added to the liquid crystal mixture to improve the solar stability of the liquid crystal device. The devices were switched between 0 and 24 volts to achieve T_min ^ 10% and T_max ^ 50%. The antioxidant types and amounts are listed in Table III below, where AOB refers to butylated hydoxytoluene (BHT) and AON refers to N,N’-di-sec-butyl-p-phenylenediamine. Table II: ND LC With Antioxidant

Example 4 [0084] The average dichroic ratio of M-1012 from Mitsui Fine Chemicals, Inc. was measured. A first cell having a parallel homogeneous alignment and a cell gap of 10 ^m was filled with a nematic liquid crystal mixture (KH-8109-000) and a dichroic dye (M-1012), without a chiral dopant. A second cell having a parallel homogeneous alignment and a cell gap of 10 ^m was filled with the nematic liquid crystal, without chiral dopant or dichroic dye. Each cell was placed between a pair of parallel polarizers. The transmittance of the first cell with its alignment direction Attorney Docket No. SP23-006PCT parallel to the transmission axis of the polarizers was measured as TŒ. The transmittance of the first cell with its alignment direction orthogonal to the transmission axis of the polarizers was measured as T^. Similarly, the transmittance of the second cell with its alignment direction parallel and orthogonal to the transmission axis of the polarizers were measured as T₀Œand T₀^, respectively. The dichroic ratio (DR) was derived as: DR = AŒ/A^ = (AŒ*wt%*cell gap)/(A^*wt%*cell gap) = Ln(TŒ/T₀Œ)/Ln(T^/ T₀^ where wt% represents the weight percent of dichroic dye. [0085] At wavelengths of 450, 550, and 650 nm, the measured dichroic ratio was 7.6, 9.2, 8.3, respectively. The average dichroic ratio over those wavelengths was greater than 8.3. [0086] It will be appreciated that the various disclosed embodiments may involve particular features, elements or steps that are described in connection with that particular embodiment. It will also be appreciated that a particular feature, element or step, although described in relation to one particular embodiment, may be interchanged or combined with alternate embodiments in various non-illustrated combinations or permutations. [0087] While various features, elements or steps of particular embodiments may be disclosed using the transitional phrase “comprising,” it is to be understood that alternative embodiments, including those that may be described using the transitional phrases “consisting” or “consisting essentially of,” are implied. Thus, for example, implied alternative embodiments to a device that comprises A+B+C include embodiments where a device consists of A+B+C and embodiments where a device consists essentially of A+B+C. [0088] It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit and scope of the disclosure. Since modifications combinations, sub- combinations and variations of the disclosed embodiments incorporating the spirit and substance of the disclosure may occur to persons skilled in the art, the disclosure should be construed to include everything within the scope of the appended claims and their equivalents.

Claims

Attorney Docket No. SP23-006PCT WHAT IS CLAIMED IS: 1. A liquid crystal device comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal device is a normally dark liquid crystal device having a minimum light transmittance (Tmin) in the absence of voltage and a maximum light transmittance (Tmax) when voltage is applied, wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye, wherein the nematic liquid crystal comprises a birefringence (ǻn) and a positive dielectric anisotropy (ǻഎ), ǻn < 0.11, and

/ǻn > 30, wherein a twisting angle of the nematic liquid crystal ranges from 450 degrees to 2000 degrees in the absence of voltage, and wherein the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer, wherein the liquid crystal layer has a cell gap (d), and wherein (d*wt%) ranges from 20 to about 28 (^mÂ%). 2. A liquid crystal device comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal device is a normally transparent liquid crystal device having a maximum light transmittance (Tmax) in the absence of voltage and a minimum light transmittance (Tmin) when voltage is applied, wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye, Attorney Docket No. SP23-006PCT wherein the nematic liquid crystal comprises a birefringence (ǻn) and a negative dielectric anisotropy (ǻഎ), ǻn < 0.11, and ¥

> 30, wherein a twisting angle of the nematic liquid crystal ranges from 225 degrees to 450 degrees when voltage is applied, and wherein the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer, wherein the liquid crystal layer has a cell gap (d), and wherein (d*wt%) ranges from 28 to 32 (^mÂ%). 3. The liquid crystal device of claim 1 or 2, wherein the first substrate assembly further comprises a first alignment layer, and wherein the first electrode layer is disposed between the first glass substrate and the first alignment layer. 4. The liquid crystal device of any of claims 1-3, wherein the second substrate assembly further comprises a second alignment layer, and wherein the second electrode layer is disposed between the second glass substrate and the second alignment layer. 5. The liquid crystal device of any of claims 1-4, wherein the cell gap (d) is at least about 5 μm. 6. The liquid crystal device of any of claims 1-5, wherein the cell gap (d) ranges from about 5 ^m to about 10 μm. 7. The liquid crystal device of any of claims 1-6, wherein the cell gap (d) ranges from about 8 ^m to about 10 ^m. 8. The liquid crystal device of any of claims 1-7, wherein Tmax is greater than or equal to 50% and Tmin is less than or equal to 10%. 9. The liquid crystal device of any of claims 1-8, wherein the liquid crystal layer further comprises at least one antioxidant. 10. The liquid crystal device of any of claims 1-9, wherein ǻn < 0.1. Attorney Docket No. SP23-006PCT 11. The liquid crystal device of any of claims 1-10, wherein ǻn < 0.1 and

40. 12. A liquid crystal device comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye; wherein the liquid crystal layer comprises a cell gap (d) ranging from about 5 ^m to about 10 ^m; and wherein the liquid crystal device comprises a maximum light transmission (Tmax) greater than or equal to 50% and a minimum light transmission (Tmin) less than or equal to 10%. 13. The liquid crystal device of claim 12, wherein the first substrate assembly further comprises a first alignment layer, and wherein the first electrode layer is disposed between the first glass substrate and the first alignment layer. 14. The liquid crystal device of claim 12 or 13, wherein the second substrate assembly further comprises a second alignment layer, and wherein the second electrode layer is disposed between the second glass substrate and the second alignment layer. 15. The liquid crystal device of any of claims 12-14, wherein the liquid crystal device is a normally transparent liquid crystal device with Tmax in the absence of voltage and Tmin when voltage is applied. 16. The liquid crystal device of claim 15, wherein the nematic liquid crystal comprises a negative dielectric anisotropy (ǻഎ). Attorney Docket No. SP23-006PCT 17. The liquid crystal device of claim 15 or 16, wherein a total twisting angle of the nematic liquid crystal ranges from 225 degrees to 450 degrees when voltage is applied. 18. The liquid crystal device of any of claims 15-17, wherein the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer, and wherein (d*wt%) ranges from 28 to 32 (^mÂ%). 19. The liquid crystal device of any of claims 12-14, wherein the liquid crystal device is a normally dark liquid crystal device with T_min in the absence of voltage and Tmax when voltage is applied. 20. The liquid crystal device of claim 19, wherein the nematic liquid crystal comprises a positive dielectric anisotropy (ǻഎ). 21. The liquid crystal device of claim 19 or 20, wherein a total twisting angle of the nematic liquid crystal ranges from 450 degrees to 2000 degrees in the absence of voltage. 22. The liquid crystal device of any of claims 19-21, wherein the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer, and wherein (d*wt%) ranges from about 20 to about 28 (^mÂ%). 23. The liquid crystal device of any of claims 12-22, wherein the liquid crystal layer further comprises at least one antioxidant. 24. The liquid crystal device of any of claims 12-23, wherein the nematic liquid crystal comprises a birefringence (ǻn) and a dielectric anisotropy (ǻഎ), ǻn < 0.11, and

30. 25. The liquid crystal device of claim 24, wherein ǻn < 0.1. 26. The liquid crystal device of claim 24 or 25, wherein

/ǻn > 40. Attorney Docket No. SP23-006PCT 27. A liquid crystal device comprising: (a) a first substrate assembly comprising a first glass substrate and a first electrode layer; (b) a second substrate assembly comprising a second glass substrate and a second electrode layer; and (c) a liquid crystal layer disposed between the first substrate assembly and the second substrate assembly; wherein the liquid crystal layer comprises a nematic liquid crystal, at least one chiral dopant, and at least one black dichroic dye; wherein the liquid crystal layer comprises a cell gap (d) greater than or equal to 5 ^m; and wherein the nematic liquid crystal comprises a birefringence (ǻn) and a dielectric anisotropy (ǻഎ), ǻn < 0.11, and ¥(ŇǻഎŇ)/ǻn > 30. 28. The liquid crystal device of claim 27, wherein the liquid crystal device is a normally dark liquid crystal device having a minimum light transmittance (Tmin) in the absence of voltage and a maximum light transmittance (Tmax) when voltage is applied, and wherein: (i) a twisting angle of the nematic liquid crystal ranges from 450 degrees to 2000 degrees in the absence of voltage, (ii) the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer and (d*wt%) ranges from 20 to about 28 (^mÂ%), or (iii) both (i) and (ii). 29. The liquid crystal device of claim 27, wherein the liquid crystal device is a normally transparent liquid crystal device having a maximum light transmittance (Tmax) in the absence of voltage and a minimum light transmittance (Tmin) when voltage is applied, and wherein: (i) a twisting angle of the nematic liquid crystal ranges from 225 degrees to 450 degrees when voltage is applied, Attorney Docket No. SP23-006PCT (ii) the at least one dichroic dye has a concentration by weight (wt%) in the liquid crystal layer and (d*wt%) ranges from 28 to 32 (^mÂ%), or (iii) both (i) and (ii). 30. The liquid crystal device of claim 28 or 29, wherein T_max ^ 50% and T_min ^ 10%. 31. The liquid crystal device of any of claims 1-30, further comprising: (d) a third substrate assembly comprising an interstitial substrate; and (e) a second liquid crystal layer; wherein the third substrate assembly is disposed between the first substrate assembly and the second substrate assembly, wherein the liquid crystal layer is disposed between the first substrate assembly and the third substrate assembly, and wherein the second liquid crystal layer is disposed between the third substrate assembly and the second substrate assembly. 32. The liquid crystal device of claim 31, wherein the third substrate assembly further comprises a third alignment layer and a fourth alignment layer, and wherein the interstitial substrate is disposed between the third and fourth alignment layers. 33. The liquid crystal device of any of claims 1-32, wherein the liquid crystal device is a switchable liquid crystal window.