Liquid crystal element, display device, and light control device

Abstract

Provided is a liquid crystal element (100) that has memory properties for reflected color. The liquid crystal element comprises: a liquid crystal composition layer (50) which includes a chiral agent that is capable of a redox reaction, a liquid crystal compound, and an electrolyte; a counter electrode material layer (30) which includes a substance that is capable of a redox reaction; a reverse reaction suppression layer (40) which suppresses a reverse reaction of a redox reaction; a first electrode (22); and a second electrode (24). In the liquid crystal element, the reverse reaction suppression layer separates the liquid crystal composition layer and the counter electrode material layer.

Description

Liquid crystal element, display device and light control device

[0001] The present invention relates to a liquid crystal element, a display device, and a light control device.

[0002] Liquid crystal display devices are used in a variety of places, including personal computers and televisions. Backlights are used in liquid crystal display devices, and they hold the key to further reducing the power consumption of these devices. Cholesteric liquid crystals are liquid crystals that can selectively reflect light, and reflective displays using these liquid crystals are devices that can control light with low power consumption. For example, Japanese Patent Application Laid-Open No. 2019-151597 and J. Am. Chem. Soc., 2018, 140, 10946 propose using a compound in which ferrocene is introduced as a redox moiety into a binaphthyl skeleton, which is a chiral moiety, as a chiral dopant to form cholesteric liquid crystal. Furthermore, it is said that the reflection wavelength of cholesteric liquid crystals can be controlled by applying a voltage to a liquid crystal composition layer containing a chiral dopant into which ferrocene has been introduced using a redox reaction.

[0003] An object of one embodiment of the present invention is to provide a liquid crystal element having a memory property of reflected color.

[0004] A first aspect is a liquid crystal element comprising a liquid crystal composition layer containing a redox-reactive chiral agent, a liquid crystalline compound, and an electrolyte, a counter electrode material layer containing a redox-reactive substance, a reverse reaction suppression layer that suppresses a reverse reaction of the redox reaction, and a first electrode and a second electrode. In the liquid crystal element, the reverse reaction suppression layer separates the liquid crystal composition layer from the counter electrode material layer.

[0005] A second aspect is a display device or a light control device including the liquid crystal element of the first aspect.

[0006] According to one embodiment of the present invention, a liquid crystal element having a memory property of reflected color can be provided.

[0007] Fig. 1 is a schematic cross-sectional view showing an example of the configuration of a liquid crystal element. Fig. 2 is a schematic cross-sectional view showing another example of the configuration of a liquid crystal element. Fig. 3 is a diagram showing changes in transmission spectrum in a liquid crystal element according to Example 1. Fig. 4 is a diagram showing changes over time in transmittance in a liquid crystal element according to Example 1. Fig. 5 is a diagram showing changes over time in transmittance in a liquid crystal element according to Comparative Example 1.

[0008] As used herein, the term "process" refers not only to an independent process, but also to processes that are not clearly distinguishable from other processes, as long as the intended purpose of the process is achieved. Furthermore, when multiple substances corresponding to each component are present in the composition, the content of each component in the composition refers to the total amount of the multiple substances present in the composition, unless otherwise specified. Furthermore, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. As used herein, when a layer, film, region, plate, or other portion is described as being "on" or "above" another portion, this includes not only the case where the portion is "directly above" the other portion, but also the case where there is another portion between them. Conversely, when a layer, film, region, plate, or other portion is described as being "below" or "below" another portion, this includes not only the case where the portion is "directly below" the other portion, but also the case where there is another portion between them. Furthermore, as used herein, "arranged above" includes not only the case where the portion is "on" but also the case where there is another portion between them.

[0009] Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below exemplify liquid crystal elements for embodying the technical concept of the present invention, and the present invention is not limited to the liquid crystal elements described below. The components described in the claims are in no way limited to the components described in the embodiments. The dimensions, materials, shapes, and relative positions of components described in the embodiments are not intended to limit the scope of the present invention, and are merely illustrative unless otherwise specified. The size and relative positions of components shown in the drawings may be exaggerated for clarity. Furthermore, in the following description, the same names and symbols indicate identical or similar components, and detailed descriptions will be omitted as appropriate. Furthermore, the elements constituting the present invention may be configured with the same components, so that multiple components are shared by one component, or conversely, the functions of one component may be shared by multiple components. Furthermore, the content described in some examples and embodiments may be applicable to other examples and embodiments.

[0010] Liquid crystal element The liquid crystal element comprises a liquid crystal composition layer containing a redox-reactive chiral agent, a liquid crystalline compound, and an electrolyte, a counter electrode material layer containing a redox-reactive substance, a reverse reaction suppression layer that suppresses the reverse reaction of the redox reaction, and a first electrode and a second electrode. In the liquid crystal element, the reverse reaction suppression layer separates the liquid crystal composition layer from the counter electrode material layer. The liquid crystal element may further comprise a pair of substrates that hold the liquid crystal composition layer, the reverse reaction suppression layer, and the counter electrode material layer. Furthermore, the liquid crystal element may further comprise a black plate, an anti-reflection film, a brightness enhancement film, etc., as necessary.

[0011] In a liquid crystal element including a liquid crystal composition layer containing a redox-reactive chiral dopant and a counter electrode material layer, application of a voltage causes a redox reaction between the chiral dopant and a redox-reactive substance contained in the counter electrode material layer, thereby changing the period (pitch) of the helical structure formed by the liquid crystal composition and changing the wavelength of the selectively reflected circularly polarized light. When the applied voltage is removed, the chiral dopant, whose structure has changed due to the redox reaction, returns to its original structure through a reverse reaction, thereby restoring the period of the helical structure to its original state. In the liquid crystal element of this embodiment, the liquid crystal composition layer and the counter electrode material layer are separated by a reverse reaction suppression layer, thereby suppressing the reverse reaction after removal of the voltage, maintaining the period of the helical structure in the state when the voltage was applied, and achieving a memory property for the reflected color. In other words, the memory property for the reflected color means that the reflected color changed by application of a voltage is maintained even after the application of the voltage is stopped. The maintenance time for the changed reflected color may be, for example, 3 seconds or more, or 30 seconds or more.

[0012] An example of the configuration of a liquid crystal element will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a liquid crystal element. The liquid crystal element 100 includes a first electrode 22, a counter electrode material layer 30 disposed on the first electrode 22, a reverse reaction suppression layer 40 disposed on the counter electrode material layer 30, a liquid crystal composition layer 50 disposed on the reverse reaction suppression layer 40, and a second electrode 24 disposed on the liquid crystal composition layer 50. The first electrode 22 is disposed on a first substrate 12, and the second electrode 24 is disposed on a second substrate 14. As shown in FIG. 1, the first electrode 22 and the second electrode 24 are disposed opposite each other. The counter electrode material layer 30 disposed in contact with the first electrode 22 and the liquid crystal composition layer 40 disposed in contact with the second electrode 24 are stacked with the reverse reaction suppression layer 40 interposed therebetween.

[0013] 2 is a schematic cross-sectional view showing another example of the configuration of a liquid crystal element. The liquid crystal element 200 includes a first electrode 22, a counter electrode material layer 30 disposed on the first electrode 22, a second electrode 24, a liquid crystal composition layer 50 disposed on the second electrode 24, and a reverse reaction suppression layer 40 disposed to separate the counter electrode material layer 30 and the liquid crystal composition layer 50. The first electrode 22 and the second electrode 24 are disposed on a first substrate 12 and separated by the reverse reaction suppression layer 40. The second substrate 14 is disposed on the counter electrode material layer 30, the liquid crystal composition layer 50, and the reverse reaction suppression layer 40. The counter electrode material layer 30 disposed in contact with the first electrode 22 and the liquid crystal composition layer 40 disposed in contact with the second electrode 24 are disposed in a direction perpendicular to the stacking direction of the liquid crystal element 200, with the reverse reaction suppression layer 40 interposed therebetween.

[0014] Liquid crystal composition layer The liquid crystal composition layer is made of a liquid crystal composition containing a redox-reactive chiral agent, a liquid crystalline compound, and an electrolyte. The liquid crystal composition can exhibit, for example, cholesteric liquid crystal. Furthermore, the liquid crystal composition exhibits selective reflection, and the selective reflection wavelength can be changed by the redox reaction of the chiral agent in an electric field.

[0015] The liquid crystal composition contains a chiral agent capable of oxidation-reduction reaction (hereinafter, sometimes simply referred to as "chiral agent"). The liquid crystal composition may contain the chiral agent as a liquid crystal compound, or may contain a liquid crystal compound different from the chiral agent as a host liquid crystal and contain the chiral agent as a chiral dopant. The content of the chiral agent in the liquid crystal composition may be, for example, 0.1 mol % or more and 10 mol % or less, and preferably 0.5 mol % or more and 5 mol % or less. The chiral agent will be described in detail later.

[0016] The liquid crystal compound constituting the liquid crystal composition can be a liquid crystal compound showing a nematic phase or a liquid crystal compound showing a smectic phase, and preferably a liquid crystal compound showing a nematic phase.Specific examples of the liquid crystal compound include azomethine compounds, cyanobiphenyl compounds, cyanophenyl ester compounds, fluorine-substituted phenyl ester compounds, cyclohexanecarboxylic acid phenyl ester compounds, fluorine-substituted cyclohexanecarboxylic acid phenyl ester compounds, cyanophenylcyclohexane compounds, fluorine-substituted phenylcyclohexane compounds, cyanophenylpyrimidine compounds, fluorine-substituted phenylpyrimidine compounds, alkoxyphenylpyrimidine compounds, fluorine-substituted alkoxyphenylpyrimidine compounds, phenyldioxane compounds, tolan compounds, fluorine-substituted tolan compounds, and alkenylcyclohexylbenzonitrile compounds.For details of the liquid crystal compound, refer to, for example, the description in Liquid Crystal Device Handbook, edited by the 142nd Committee of the Japan Society for the Promotion of Science, Nikkan Kogyo Shimbun, 1989, pages 154-192 and 715-722.

[0017] Specific examples of the liquid crystal compound include liquid crystal compounds exhibiting a nematic phase such as 4-cyano-4'-pentyloxybiphenyl (5OCB), 4-cyano-4'-pentylbiphenyl (5CB), etc. The content of the liquid crystal compound in the liquid crystal composition may be the remainder other than the chiral agent, the electrolyte contained as needed, and various additives.

[0018] The liquid crystal composition may further contain an electrolyte. By including an electrolyte, sufficient conductivity can be imparted to the liquid crystal composition, and the oxidation-reduction reaction of the chiral agent (for example, the compound represented by formula (1)) becomes easier. The electrolyte may be a supporting electrolyte constituting the liquid crystal composition, and may be selected from compounds that are highly soluble in the host liquid crystal. The electrolyte may be a supporting electrolyte commonly used in electrochemistry (for example, nBu ４ NPF ６ , nBu ４ NBF ４ , nBu ４ NClO ４Examples of the ionic liquid include 1-ethyl-3-methylimidazolium triflate and 1-ethyl-3-methylimidazolium hexafluorophosphate. The liquid crystal composition may contain only one electrolyte, or a combination of two or more electrolytes. The content of the electrolyte in the liquid crystal composition may be, for example, 0.1 mol % or more and 30 mol % or less, and preferably 0.5 mol % or more and 15 mol % or less.

[0019] Various liquid crystal and non-liquid crystal compounds can be added to the liquid crystal composition for the purposes of changing the physical properties of the host liquid crystal (e.g., the temperature range of the liquid crystal phase) to a desired range, promoting the oxidation-reduction reaction, etc. Furthermore, additives such as ultraviolet absorbers and antioxidants may also be added.

[0020] The thickness of the liquid crystal composition layer in the liquid crystal element may be, for example, 1 μm or more and 100 μm or less, and preferably 1 μm or more or 50 μm or less.

[0021] Counter Electrode Material Layer The counter electrode material layer is composed of a counter electrode material, which is a substance capable of undergoing a redox reaction. The counter electrode material may be a substance that is oxidized and reduced in response to the redox reaction of the chiral agent. The counter electrode material may be any substance capable of reversible redox reaction, and may be organic or inorganic. Specific examples of the counter electrode material include organic substances such as poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole, and polyaniline, and inorganic substances such as Prussian blue and tungsten oxide. Preferably, the counter electrode material may contain at least one selected from the group consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and Prussian blue. The organic substance such as PEDOT used as the counter electrode material may be a block copolymer with polyethylene glycol (PEG) or the like. Examples of block copolymers of PEDOT and PEG include Aedotron ＴＭ (manufactured by Sigma-Aldrich Co.) The content of the counter electrode material in the counter electrode material layer may be, for example, 0.1% by mass or more, and preferably 0.5% by mass or more, or 10% by mass or less.

[0022] The counter electrode layer may further contain a conductive material in addition to the substance capable of undergoing an oxidation-reduction reaction. Examples of the conductive material include conductive polymers such as polystyrene sulfonate (PSS), polypyrrole, and polyaniline, and supporting electrolytes commonly used in electrochemistry (e.g., nBu). ４ NPF ６ , nBu ４ NBF ４ , nBu ４ NClO ４ etc.) etc.

[0023] When the counter electrode material layer contains a substance capable of undergoing a redox reaction and a conductive substance, they may be contained in the counter electrode material layer as a composite. An example of the composite is PEDOT / PSS. A commercially available product may be used for the composite such as PEDOT / PSS. An example of a commercially available product is Orgacon. ＴＭ , Aedotron ＴＭ (all manufactured by Sigma-Aldrich). When the counter electrode material layer contains a composite of a redox-reactive substance and a conductive substance, the content of the composite in the counter electrode material layer may be, for example, 0.1 mass % or more, and preferably 0.5 mass % or more, or 10 mass % or less. In one aspect, the counter electrode material layer may be made of a composite of a redox-reactive substance and a conductive substance.

[0024] The thickness of the counter electrode material layer in the liquid crystal element may be, for example, 10 nm or more and 1 mm or less, and preferably 100 nm or more or 100 μm or less.

[0025] Reverse Reaction Inhibitory Layer The reverse reaction inhibitor layer inhibits the chiral agent, whose structure has changed due to an oxidation-reduction reaction, from returning to its original structure due to a reverse reaction. The reverse reaction inhibitor layer may be configured to inhibit contact between the chiral agent and the counter electrode material. For example, the reverse reaction inhibitor layer may be configured to inhibit permeation of the chiral agent. The reverse reaction inhibitor layer may be composed of a porous material or a non-porous material (e.g., a solid material). The reverse reaction inhibitor layer may be configured to contain a resin, or may be configured to contain a resin that can be applied to the counter electrode material layer to form a reverse reaction inhibitor layer. Examples of resins that can constitute the reverse reaction inhibitor layer include insulating resins such as polyethylene, polypropylene, epoxy resin, and acrylic resin, cationic or anionic ion exchange resins, and covalent organic frameworks. Specific examples of ion exchange resins include Nafion. ＴＭ , polyallylamine, etc. The reverse reaction suppression layer may be configured to contain a gel electrolyte material, a solid electrolyte material, etc.

[0026] The thickness of the reverse reaction suppression layer in the liquid crystal element may be, for example, 10 nm or more and 1 mm or less, and preferably 100 nm or more or 100 μm or less.

[0027] Electrode The electrode includes a first electrode arranged in contact with the counter electrode material and a second electrode arranged in contact with the liquid crystal composition layer. The electrode may be formed, for example, on a substrate described below. The electrode may be a transparent electrode or a non-transparent electrode. Examples of materials for forming the transparent electrode include indium oxide, indium tin oxide (ITO), tin oxide, silver nanorods, carbon nanotubes, and conductive resins such as polystyrene sulfonate. The transparent electrode can be formed by a sputtering method, a sol-gel method, or a printing method. For example, a GC electrode can be used as the non-transparent electrode.

[0028] The surface of the electrode placed in contact with the liquid crystal composition layer may be subjected to a rubbing treatment, if necessary, to further improve the alignment of the liquid crystal.

[0029] Substrates The liquid crystal element may further include a pair of substrates, which may be arranged to hold, for example, a liquid crystal composition layer, a reverse reaction suppression layer, and a counter electrode material layer.

[0030] The material of the substrate constituting the liquid crystal element may be glass, plastic, etc. Examples of plastics that can be used for the substrate include acrylic resin, polycarbonate resin, epoxy resin, polyester resin, polyamide resin, polyolefin resin, polyether resin, polysulfide resin, polysulfone resin, polyester sulfone resin, polyetherimide resin, and polyimide resin.

[0031] At least one of the pair of substrates constituting the liquid crystal element may be light-transmitting. When the substrate is light-transmitting, its haze value may be, for example, 3% or less, preferably 2% or less, or 1% or less. The total light transmittance of the light-transmitting substrate may be, for example, 70% or more, preferably 80% or more, or 90% or more.

[0032] One of the substrates may be non-light-transmitting. When a non-light-transmitting substrate is used as the substrate, a black substrate that does not have light reflectivity can be used on the non-display side. Examples of black substrates include plastic substrates to which inorganic pigments such as carbon black have been added.

[0033] Chiral Dopant The liquid crystal composition contains at least one chiral dopant capable of redox reaction. The chiral dopant may constitute the liquid crystal composition as a chiral dopant. The chiral dopant may be, for example, a compound having a structural moiety that serves as an asymmetry source and a redox reaction moiety. Examples of the structural moiety that serves as an asymmetry source include optically active skeletons having an asymmetric carbon, such as a binaphthyl skeleton. Examples of the redox reaction moiety include ferrocene, ferrocene derivatives, and arylamine derivatives. The chiral dopant may include a compound having a binaphthyl skeleton and a redox reaction moiety, such as a compound represented by the following formula (1):

[0034]

[0035] In formula (1), R ０each independently represents a functional group capable of undergoing an oxidation-reduction reaction; s and t each independently represent an integer of 0 to 6. １ and R ２ each independently represents a substituent. p + s and q + t each independently represent an integer of 0 to 6. T each independently represents a divalent linking group formed from at least one selected from the group consisting of a carbonyl group, an oxygen atom, an imino group, and an alkylene group. Q represents a trivalent linking group composed of at least one selected from the group consisting of an oxygen atom, a nitrogen atom, a carbon atom, a phosphorus atom, a sulfur atom, and a hydrogen atom.

[0036] R ０ Examples of the functional group capable of undergoing an oxidation-reduction reaction represented by the formula (I) include ferrocene, ferrocene derivatives, and arylamine derivatives, and the compound may contain at least one selected from the group consisting of these.

[0037] Each of s and t independently represents an integer of 0 to 6. Preferably, it may be an integer of 5 or less, or an integer of 2 or less, or it may be an integer of 1 or more. Furthermore, each of p and q independently represents an integer of 0 to 6. Preferably, it may be an integer of 5 or less, or an integer of 2 or less, or it may be an integer of 1 or more. Furthermore, p + s and q + t each independently represent an integer of 0 to 6. Preferably, it may be an integer of 5 or less, or an integer of 2 or less, or it may be an integer of 1 or more.

[0038] R １ and R ２ R each independently represents a substituent. １ or R ２ The substituent represented by formula (1) may be at least one selected from the group consisting of a substituted or unsubstituted hydrocarbon group, a nitro group, a cyano group, a halogen atom, a hydroxy group, an alkoxy group, an acyl group, an alkoxycarbonyl group, a carboxy group, an aliphatic amino group, and an aromatic amino group. １ or R ２ When a plurality of substituents represented by the following formula are present, they may be the same or different.

[0039] The hydrocarbon group in the substituent may be an aliphatic group or an aromatic group. The aliphatic group may be a saturated aliphatic group or an unsaturated aliphatic group. The aliphatic group may be linear, branched, cyclic, or a combination thereof. The aliphatic group may have, for example, 1 to 20 carbon atoms, preferably 1 to 10 or 1 to 6 carbon atoms. Examples of substituents in the aliphatic group include halogen atoms, aryl groups, and alkoxy groups. The aromatic group may have, for example, 6 to 18 carbon atoms, preferably 6. Examples of substituents in the aromatic group include halogen atoms, aliphatic groups having 1 to 20 carbon atoms, alkoxy groups, acyl groups, and alkoxycarbonyl groups.

[0040] The halogen atom in the substituent may include a fluorine atom, a chlorine atom, a bromine atom, etc. The alkoxy group as a substituent may have an aliphatic group having 1 to 20 carbon atoms, preferably an aliphatic group having 1 to 10 carbon atoms. The acyl group as a substituent may have an aliphatic group having 1 to 20 carbon atoms, preferably an aliphatic group having 1 to 6 carbon atoms. The alkoxycarbonyl group as a substituent may have an aliphatic group having 1 to 20 carbon atoms, preferably an aliphatic group having 1 to 6 carbon atoms.

[0041] The aliphatic group in the aliphatic amino group as a substituent may be a saturated aliphatic group or an unsaturated aliphatic group. The aliphatic group may be linear, branched, cyclic, or a combination thereof. The carbon number of the aliphatic group may be, for example, 1 to 20, preferably 1 to 10, or 1 to 6. The aliphatic amino group may be a mono-substituted aliphatic amino group having one aliphatic group, or a di-substituted aliphatic amino group having two aliphatic groups. The aliphatic amino group may further have a substituent in the aliphatic group moiety. Examples of the substituent in the aliphatic group include a halogen atom, an aryl group, an alkoxy group, an alkylamino group, and an arylamino group. The number of substitutions in the aliphatic group may be, for example, 0 to 20, preferably 10 or less.

[0042] The aromatic group in the aromatic amino group as a substituent may be an aromatic hydrocarbon group or an aromatic heterocyclic group. The number of carbon atoms in the aromatic hydrocarbon group may be, for example, 6 to 18, preferably 6 to 12. The aromatic hydrocarbon group may contain at least one selected from the group consisting of a phenyl group, a naphthyl group, and an anthracenyl group. The aromatic heterocyclic group may contain at least one heteroatom selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. The number of members in the aromatic heterocyclic group may be, for example, 5 to 10, preferably 6 or less. The aromatic heterocyclic group may contain at least one selected from the group consisting of a pyridyl group, a furyl group, and a thienyl group. The aromatic amino group may be a mono-substituted aromatic amino group having one aromatic group, or a di-substituted aromatic amino group having two aromatic groups. The aromatic amino group may further have a substituent in the aromatic group portion. Examples of substituents in the aromatic group include a halogen atom, an aryl group, an alkoxy group, an alkylamino group, an arylamino group, and an alkyl group. The number of substitutions in the aromatic group may be, for example, 0 or more and 8 or less, and preferably 5 or less.

[0043] Each T independently represents a divalent linking group formed from at least one selected from the group consisting of a carbonyl group, an oxygen atom, an imino group, and an alkylene group. The imino group in T may be substituted with a hydrocarbon group. The hydrocarbon group substituting the imino group is R １ and R ２The alkylene group represented by T may be linear, branched, or cyclic, or a combination thereof. The number of carbon atoms in the alkylene group represented by T may be, for example, 1 to 20, preferably 10 or less, or 6 or less. The divalent linking group represented by T may be a carbonyl group, an oxygen atom, an imino group, or an alkylene group, and may contain, for example, an ester bond formed by a carbonyl group and an oxygen atom bonding, an amide bond or a urea bond formed by a carbonyl group and an imino group bonding, a urethane bond formed by a carbonyl group, an imino group, and an oxygen atom bonding, or an ether bond formed by an oxygen atom bonding to an alkylene group. When a plurality of divalent linking groups represented by T are present in the aromatic amine compound, they may be the same or different.

[0044] The divalent linking group represented by T may be formed containing at least a carbonyl group. Specific examples of the divalent linking group represented by T include a carbonyl group, an oxygen atom, an imino group, an alkylene group, a carbonyloxy group, an oxycarbonyl group, an alkylenecarbonyloxy group, an alkyleneoxycarbonyl group, a carbonyloxyalkylene group, an oxycarbonylalkylene group, an iminocarbonyl group, an alkyleneiminocarbonyl group, a carbonylimino group, a carbonyliminoalkylene group, an alkyleneoxy group, an oxyalkylene group, an iminocarbonylimino group, an oxycarbonylimino group, an iminocarbonyloxy group, and the like. Preferred examples of the divalent linking group represented by T include a carbonyloxy group, an oxycarbonyl group, an oxygen atom, and the like.

[0045] Q represents a trivalent linking group consisting of at least one atom selected from the group consisting of oxygen, nitrogen, carbon, phosphorus, sulfur, and hydrogen atoms. Q may be, for example, a trivalent linking group represented by the following formula (2a) or (2b):

[0046]

[0047] In formulas (2a) and (2b), * indicates the bonding position to other atoms. １ , X ２ and X ３ are each independently an oxygen atom, a sulfur atom, or —C(R ３ ) (R ４ )- and -N(R ５ )-R ３ , R ４ and R ５ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aromatic group. １ and Y ２ each independently represents one member selected from the group consisting of a substituted or unsubstituted alkanetriyl group, a nitrogen atom, and —P(═O)(O—)—.

[0048] R ３ , R ４ or R ５ The alkyl group represented by R may be linear, branched, or cyclic, or may be a combination thereof. ３ , R ４ or R ５ The number of carbon atoms in the alkyl group represented by R may be, for example, 1 or more and 20 or less, and preferably 6 or less. ３ , R ４ or R ５ The aromatic group represented by R is formed by removing one hydrogen atom from an aromatic hydrocarbon compound or an aromatic heterocyclic compound. The aromatic hydrocarbon compound or aromatic heterocyclic compound is as described above. ３ , R ４ or R ５ The substituents in １ and R ２ The substituents are the same as those in

[0049] Y １ or Y ２ The alkanetriyl group represented by the formula (I) is formed by removing three hydrogen atoms from an alkane. The number of carbon atoms in the alkane forming the alkanetriyl group may be, for example, 1 to 20, preferably 6 or less. １or Y ２ The substituents in １ and R ２ The substituents are the same as those in

[0050] Specific examples of the trivalent linking group represented by formula (2a) include the following linking groups, but the present invention is not limited to these. The trivalent linking group represented by formula (2a) is a group represented by formula (2a) in which X １ and X ２ is bonded to the binaphthyl moiety in formula (1), and Y １ may be attached to T in formula (1).

[0051]

[0052] Specific examples of the trivalent linking group represented by formula (2b) include the following linking groups, but the present invention is not limited to these. The trivalent linking group represented by formula (2b) is a group represented by formula (2b) in which X ３ and Y ２ is bonded to the binaphthyl moiety in formula (1), and Y ２ may be attached to T in formula (1).

[0053]

[0054] The trivalent linking group represented by Q may preferably be represented by formula (2a), and more preferably, X in formula (2a) １ and X ２ may be an oxygen atom, and Y １ may be a propane-1,2,3-triyl group.

[0055] In one embodiment, the compound represented by formula (1) may be a compound represented by the following formula (1a):

[0056]

[0057] In formula (1a), R １ , R ２ , T, Q, s, t, p and q have the same meanings as those in formula (1). １ A each independently represents a substituted or unsubstituted alkylene group, or a substituted or unsubstituted divalent aromatic group. ２ and A ３A each independently represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic group. １ , A ２ and A ３ At least one of these represents an aromatic group.

[0058] A １ The alkylene group represented by the formula (I) may be linear, branched, or cyclic, or may be a combination thereof. １ The number of carbon atoms in the alkylene group represented by the formula (I) may be, for example, 1 or more and 20 or less, and preferably 1 or more or 10 or less. １ The divalent aromatic group represented by the formula (I) is formed by removing two hydrogen atoms from an aromatic hydrocarbon compound or an aromatic heterocyclic compound. The aromatic hydrocarbon compound may have 6 to 18 carbon atoms, preferably 6. The aromatic hydrocarbon compound may contain at least one selected from the group consisting of benzene, naphthalene, and anthracene. The aromatic heterocyclic compound may contain at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur atoms. The number of members of the aromatic heterocyclic compound may be, for example, 5 to 10, preferably 6 or less. The aromatic heterocyclic compound may contain at least one selected from the group consisting of pyridine, furan, and thiophene. In the aromatic amine compound, A １ When a plurality of alkylene groups or divalent aromatic groups represented by the following formula are present, they may be the same or different.

[0059] A １ The alkylene group or divalent aromatic group represented by the formula (I) may have a substituent. １ The substituents in １ and R ２ The substituents are the same as those in A. １ The number of substitutions in the alkylene group or divalent aromatic group represented by the formula (I) may be, for example, 0 or more and 20 or less, and preferably 4 or less.

[0060] A ２ or A ３The alkyl group represented by the formula (I) may be linear, branched, or cyclic, or may be a combination thereof. ２ or A ３ The number of carbon atoms in the alkyl group represented by the formula (I) may be, for example, 1 or more and 20 or less, and preferably 1 or more or 6 or less. ２ or A ３ The aromatic group represented by the formula (I) is formed by removing one hydrogen atom from an aromatic hydrocarbon compound or an aromatic heterocyclic compound. For details of aromatic hydrocarbon compounds and aromatic heterocyclic compounds, see A １ In addition, in the compound represented by formula (1a) (aromatic amine compound), A ２ or A ３ When a plurality of alkyl groups or aromatic groups represented by the formula (I) are present, they may be the same or different.

[0061] A ２ or A ３ The alkyl group or aromatic group represented by the formula (I) may have a substituent. ２ or A ３ The substituents in １ and R ２ The substituents are the same as those in A. ２ or A ３ The number of substitutions in the alkyl group or aromatic group represented by the formula (I) may be, for example, 0 or more and 20 or less, and preferably 5 or less.

[0062] A ２ or A ３ At least one of the aromatic groups represented by the formula (I) may have a substituent, and may have an aromatic amino group as the substituent. ２ or A ３The aromatic amino group substituting the aromatic group represented by the formula (I) may be an amino group having two aromatic groups, i.e., a disubstituted aromatic amino group, and the aromatic group in the aromatic amino group may further have a substituent. Examples of the substituent in the aromatic group include a halogen atom, an aryl group, an alkoxy group, an alkylamino group, an arylamino group, and an alkyl group. The number of substitutions in the aromatic group may be, for example, 0 to 9, and preferably 1 to 5.

[0063] A １ , A ２ and A ３ At least one of A represents an aromatic group, but preferably at least two may be aromatic groups, and more preferably three may be aromatic groups. １ , A ２ and A ３ At least A １ may be an aromatic group, and A ２ and A ３ At least one of them may be an aromatic group.

[0064] The compound represented by formula (1a) can be produced, for example, as follows. A dihaloalkane having a substituent is reacted with 1,1'-bi(2-naphthol) to introduce a trivalent linking group represented by Q, and an aromatic amine derivative is linked to the trivalent linking group represented by Q by a condensation reaction, a substitution reaction, a coupling reaction, or the like, to produce a compound represented by formula (1). Furthermore, by using 1,1'-bi(2-naphthol) having an appropriate substituent on the naphthyl ring, an aromatic amine derivative can be linked to the naphthyl ring. For details of the compound represented by formula (1a), reference can be made to the specification of Japanese Patent Application No. 2022-177592, for example.

[0065] In one embodiment, the compound represented by formula (1) may be a compound represented by the following formula (1b):

[0066]

[0067] In formula (1b), R １ , R ２, T, Q, s, t, p, and q have the same meanings as those in formula (1). Fc each independently represents ferrocene or a ferrocene derivative. The ferrocene or ferrocene derivative represented by Fc may be, for example, a functional group represented by the following formula (3):

[0068]

[0069] In formula (3), R ７ , R ８ , R ９ , R １０ , R １１ , R １２ , R １３ , R １４ and R １５ each independently represents a hydrogen atom or a substituent, and * indicates the bonding position to T in formula (1b).

[0070] R ７ , R ８ , R ９ , R １０ , R １１ , R １２ , R １３ , R １４ or R １５ Examples of the substituent represented by R include an alkyl group, a halogen atom, and an alkoxy group. ７ The alkyl group represented by R may be linear, branched, or cyclic, or may be a combination thereof. The number of carbon atoms in the alkyl group may be, for example, 1 or more and 20 or less, preferably 1 to 10, or 1 to 8. ７ The halogen atoms represented by R include fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc. ７ The alkyl group portion of the alkoxy group represented by the formula (I) may be linear, branched, cyclic, or a combination thereof, and may further have a substituent. The number of carbon atoms in the alkyl group portion of the alkoxy group may be, for example, 1 to 20, preferably 1 to 10, or 1 to 8. Examples of the substituent in the alkoxy group include an alkoxy group having 1 to 6 carbon atoms, an aryloxy group, etc.

[0071] For the compound represented by formula (1b), reference can be made to the description in, for example, JP-A-2019-151597.

[0072] The liquid crystal element may also include other members such as a barrier film, an ultraviolet absorbing layer, an anti-reflection layer, a hard coat layer, an anti-fouling layer, an organic interlayer insulating film, a metal reflector, a retardation film, an alignment film, etc. These may be used alone or in combination of two or more.

[0073] The liquid crystal element can be driven by a simple matrix driving method or an active matrix driving method using thin film transistors (TFTs) or the like.

[0074] In the liquid crystal element, the absolute value of the driving voltage may be, for example, 0.1 V or more and 20 V or less, preferably 0.3 V or more and 15 V or less, or 0.5 V or more and 1.0 V or less.

[0075] Display device A display device includes the above-described liquid crystal element. By including a liquid crystal element configured to be able to adjust the color by changing the voltage applied to the liquid crystal layer, it is possible to configure a reflective display device driven by a simple matrix driving method or an active matrix driving method.

[0076] A light control device includes the liquid crystal element described above. By including a liquid crystal element configured to be able to adjust the color by applying a voltage to the liquid crystal layer, it is possible to configure a light control device that exhibits a desired reflected light color or transmitted light color of circularly polarized light.

[0077] The invention according to the present disclosure may include, for example, the following aspects: [1] A liquid crystal element comprising: a liquid crystal composition layer containing a redox-reactive chiral agent, a liquid crystalline compound, and an electrolyte; a counter electrode material layer containing a redox-reactive substance; a reverse reaction suppression layer that suppresses a reverse redox reaction; and a first electrode and a second electrode, wherein the reverse reaction suppression layer separates the liquid crystal composition layer from the counter electrode material layer.

[0078] [2] The liquid crystal element according to [1], comprising: the first electrode; a counter electrode material layer disposed on the first electrode; a reverse reaction suppression layer disposed on the counter electrode material layer; a liquid crystal composition layer disposed on the reverse reaction suppression layer; and a second electrode disposed on the liquid crystal composition layer.

[0079] [3] The liquid crystal element according to [1] or [2], wherein the reverse reaction suppression layer suppresses transmission of the chiral agent.

[0080] [4] The liquid crystal element according to any one of [1] to [3], wherein the reverse reaction suppression layer contains a resin.

[0081] [5] The liquid crystal element according to any one of [1] to [4], wherein the chiral agent includes a compound having a binaphthyl skeleton and a redox reaction site.

[0082] [6] The liquid crystal element according to any one of [1] to [5], wherein the counter electrode material layer contains at least one selected from the group consisting of poly(3,4-ethylenedioxythiophene) and Prussian blue.

[0083] [7] A display device or a light control device comprising the liquid crystal element according to any one of [1] to [6].

[0084] In other aspects, the present invention also encompasses the use of the chiral agent in the production of the liquid crystal device, and the chiral agent used in the liquid crystal device.

[0085] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0086] Preparation Example 1 Synthesis of precursor TPA-OMe-COOH

[0087]

[0088] As shown in the above scheme, under a nitrogen atmosphere, 1.15 g (5.0 mmol) of 4,4'-dimethoxydiphenylamine (Tokyo Chemical Industry Co., Ltd.), 1.40 g (5.2 mmol) of methyl 4-iodobenzoate (Tokyo Chemical Industry Co., Ltd.), 0.72 g (7.5 mmol) of sodium tert-butoxide (Tokyo Chemical Industry Co., Ltd.), 0.15 g (0.5 mmol) of tri-tert-butylphosphonium tetrafluoroborate (Tokyo Chemical Industry Co., Ltd.), 0.15 g (0.25 mmol) of bis(dibenzylideneacetone)palladium(0) (Fujifilm Wako Pure Chemical Industries, Ltd.), and 100 mL of toluene (ultra-dehydrated) (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a three-neck flask and stirred under reflux for 7 hours, followed by stirring at room temperature. After one day, the reaction solution was slowly added to 250 mL of 1 M aqueous ammonia to quench the reaction. The mixture was then filtered through Celite and washed with toluene. After the aqueous layer was removed by separation, the organic layer was further separated with saturated saline, dehydrated with magnesium sulfate, and then the solvent was removed with an evaporator. The residue was dried under reduced pressure to obtain a reddish-brown oily substance, TPA-OMe-COOMe.

[0089] The oily TPA-OMe-COOMe was dissolved in 50 mL of THF (FUJIFILM Wako Pure Chemical Industries, Ltd.) and 50 mL of ethanol (FUJIFILM Wako Pure Chemical Industries, Ltd.). 50 mL of 2M aqueous potassium hydroxide solution was added, and the mixture was heated to reflux for 1 hour. After cooling, the THF and ethanol were removed using an evaporator, 100 mL of ultrapure water was added, and 2M aqueous HCl was slowly added until the solution became acidic, producing a yellow-white precipitate. 200 mL of dichloromethane (FUJIFILM Wako Pure Chemical Industries, Ltd.) was added to dissolve the yellow-white precipitate, and the aqueous layer was removed by separation. The mixture was then separated with saturated saline, and the organic layer was dehydrated with magnesium sulfate. The solvent was then removed using an evaporator and dried under reduced pressure, yielding a yellow-brown oily substance. The oily substance was then purified using a silica gel column with a 1:1 ethyl acetate:hexane mixture as a developing solvent, and the target compound was isolated (Rf = 0.5). After removing the solvent with an evaporator, the product was dried under reduced pressure to obtain 400 mg of the precursor TPA-OMe-COOH as a white powder. １ H-NMR was used.

[0090] 1 H-NMR (400 MHz, CDCl3): δ(ppm) 7.84(d, 2H), 7.11(d, 4H), 6.88(d, 4H), 6.81(d, 2H), 3.82(s, 6H).

[0091] Synthesis of compound BN-TPA-OMe

[0092]

[0093] Under a nitrogen atmosphere, 0.18 g (0.5 mmol) of the compound TPA-OMe-COOH, 0.18 g (0.5 mmol) of BN-OH, 0.14 g (0.75 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (Tokyo Chemical Industry Co., Ltd.), 0.06 g (0.5 mmol) of 4-dimethylaminopyridine (Tokyo Chemical Industry Co., Ltd.), and 30 mL of dichloromethane (Fujifilm Wako Co., Ltd.) were added to a three-neck flask and stirred at room temperature for one day. The reaction solution was extracted with dichloromethane and separated with saturated saline, after which the organic layer was dehydrated with magnesium sulfate. The solvent was removed using an evaporator, and the mixture was dried under reduced pressure to obtain a pale yellow powder. The target compound BN-TPA was purified using a silica gel column with a 1:1 mixture of ethyl acetate and hexane as a developing solvent (Rf = 0.5). After removing the solvent with an evaporator, the residue was dried under reduced pressure to obtain 0.22 g of the final target compound BN-TPA as a yellowish white powder. １ H-NMR and ESI-MS were used. BN-OH was synthesized with reference to a known method (e.g., J. Am. Chem. Soc., 2018, 140, 10946).

[0094] 1H-NMR(400 MHz, CDCl3):δ(ppm) 7.96(dd, 2H), 7.88(d, 2H), 7.74(d, 2H), 7.56(d, 1H), 7.41(d, 1H) 7.35-7.39(m, 2H), 7.21-7.25(m, 2H+2H), 7.10(d, 4H), 6.87(d, 4H), 6.79(d, 2H), 4.73(dd, 1H), 4.61(d, 1H), 4.10-4.33(m, 4H), 3.81(s, 6H), 2.61-2.66(m, 1H); ESI-MS: m / z calc for C 45 H 37 NO6: 688.27 [M+H] + ; found 688.27.

[0095] Example 1 A compound BN-TPA-OMe was dissolved in a methylene chloride solution of host liquid crystal molecules, which was a 7:3 mixture of 4-cyano-4'-pentyloxybiphenyl and 4-cyano-4'-pentylbiphenyl, to a final concentration of 3 mol%, and 1-ethyl-3-methylimidazolium triflate was added thereto. The mixture was then concentrated under reduced pressure to prepare a liquid crystal composition.

[0096] Using the prepared liquid crystal composition, a liquid crystal device having the configuration shown in Figure 1 was fabricated. A counter electrode layer was formed by spin-coating PEDOT / PSS on one side of an ITO glass cell having a cell thickness of 10 μm. Next, Nafion was applied to the counter electrode layer. ＴＭ The liquid crystal composition prepared above was introduced into a cell in which the counter electrode material layer and the reverse reaction suppression layer were formed, thereby producing a liquid crystal device of Example 1.

[0097] Comparative Example 1 Nafion on the counter electrode material layer ＴＭ A liquid crystal element of Comparative Example 1 was produced in the same manner as in Example 1, except that no film was formed.

[0098] Evaluation 1: The change in reflection color of the liquid crystal element obtained in Example 1 was measured by measuring the transmission spectrum using an ultraviolet-visible spectrophotometer (UV1800, manufactured by Shimadzu Corporation). The results are shown in Figure 3. (a) The dashed line is the transmission spectrum before voltage application, (b) the solid line is the transmission spectrum during application of 2.5 V, and (c) the dashed-dotted line is the transmission spectrum immediately after (30 seconds after) the application of voltage was stopped.

[0099] As shown in FIG. 3, the transmission spectrum changes when a voltage is applied from a no-voltage state, and even after the voltage application is stopped, the transmission spectrum remains the same as when the voltage is applied.

[0100] Evaluation 2: The change in transmittance over time of the liquid crystal element obtained above was measured at a wavelength of 540 nm using an ultraviolet-visible spectrophotometer (UV1800, manufactured by Shimadzu Corporation). Starting from a state in which no voltage was applied, a voltage was applied for 30 seconds, and then the voltage application was stopped, and the change in transmittance was measured over the next 90 seconds. The measurement results for the liquid crystal element of Example 1 are shown in FIG. 4, and the measurement results for the liquid crystal element of Comparative Example 1 are shown in FIG. 5.

[0101] In the liquid crystal element of Example 1, the transmittance at 540 nm decreased when a voltage was applied, as shown in Fig. 4. After the voltage application was stopped, the transmittance gradually increased, reaching approximately 30% after 90 seconds. In the liquid crystal element of Comparative Example 1, the transmittance rapidly increased after the voltage application was stopped, reaching 100% after 90 seconds, as shown in Fig. 5.

[0102] The disclosure of Japanese Patent Application No. 2023-066923 (filing date: April 17, 2023) is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. a liquid crystal composition layer including a redox-reactive chiral agent, a liquid crystal compound, and an electrolyte; a counter electrode material layer including a redox-reactive substance; a reverse reaction suppression layer that suppresses a reverse reaction of the redox reaction; and a first electrode and a second electrode; The liquid crystal element, wherein the reverse reaction suppression layer separates the liquid crystal composition layer from the counter electrode material layer.

2. 2. The liquid crystal element according to claim 1, comprising: the first electrode; a counter electrode material layer disposed on the first electrode; a reverse reaction suppression layer disposed on the counter electrode material layer; a liquid crystal composition layer disposed on the reverse reaction suppression layer; and a second electrode disposed on the liquid crystal composition layer.

3. 2. The liquid crystal device according to claim 1, wherein the reverse reaction suppression layer suppresses transmission of the chiral agent.

4. The liquid crystal device according to claim 1 , wherein the reverse reaction suppression layer contains a resin.

5. 2. The liquid crystal device according to claim 1, wherein the chiral agent includes a compound having a binaphthyl skeleton and a redox reaction site.

6. 2. The liquid crystal device according to claim 1, wherein the counter electrode layer contains at least one material selected from the group consisting of poly(3,4-ethylenedioxythiophene) and Prussian blue.

7. A display device or a light control device comprising the liquid crystal element according to claim 1 .