Liquid crystal composition, liquid crystal element, display device, and dimming device

Abstract

Provided are: a liquid crystal composition capable of the electrical multi-stage modulation of a reflection color in a liquid crystal element; and a liquid crystal element including the same. The liquid crystal composition includes at least two kinds of chiral agents having different oxidation-reduction potentials. The liquid crystal element comprises: a liquid crystal composition layer including at least two kinds of chiral agents having different oxidation-reduction potentials; a counter electrode material layer including a substance capable of undergoing an oxidation-reduction reaction; and a first electrode and a second electrode.

Description

Liquid crystal composition, liquid crystal element, display device and light control device

[0001] The present invention relates to a liquid crystal composition, 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] Furthermore, a liquid crystal element capable of expressing a plurality of reflected colors by light irradiation using photoisomerizable molecules has been proposed (see, for example, Macromol. Rapid Commun., 2019, 40, 1900037).

[0004] However, the techniques proposed in JP 2019-151597 A and J. Am. Chem. Soc., 2018, 140, 10946., when configuring a liquid crystal element, can only express two reflected colors corresponding to ON and OFF voltages, respectively. Furthermore, the technique proposed in Macromol. Rapid Commun., 2019, 40, 1900037. expresses multiple reflected colors by light irradiation, and cannot be applied to liquid crystal elements that can electrically express reflected colors in multiple stages.

[0005] An object of one embodiment of the present invention is to provide a liquid crystal composition that enables electrical multi-stage modulation of reflected color in a liquid crystal element, a liquid crystal element including the same, and a display device and a light control device including the liquid crystal element.

[0006] A first aspect is a liquid crystal composition containing two or more chiral agents having different redox potentials. A second aspect is a liquid crystal element comprising a liquid crystal composition layer containing two or more chiral agents having different redox potentials, a counter electrode material layer containing a substance capable of redox reaction, and a first electrode and a second electrode. A third aspect is a display device or a light control device comprising the liquid crystal element of the second aspect.

[0007] According to one embodiment of the present invention, it is possible to provide a liquid crystal composition that enables electrical multi-stage modulation of reflected color in a liquid crystal element, a liquid crystal element including the same, and a display device and a light control device including the liquid crystal element.

[0008] 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 schematic cross-sectional view showing another example of the configuration of a liquid crystal element; Fig. 4 is an example of a cyclic voltammogram of a liquid crystal composition with ferrocene as the standard; Fig. 5 is a diagram showing changes in the transmission spectrum in a liquid crystal element.

[0009] As used herein, the content of each component in a composition refers to the total amount of each component present in the composition unless otherwise specified, when multiple substances corresponding to each component are present in the composition. 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 it is "directly above" the other portion, but also the case where there is another portion in between. 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 it is "directly below" the other portion, but also the case where there is another portion in between. Furthermore, as used herein, "arranged above" includes not only the case where it is arranged above, but also the case where it is arranged below.

[0010] Embodiments of the present invention are described in detail below. However, the embodiments described below exemplify liquid crystal compositions, liquid crystal elements, and the like to embody the technical concepts of the present invention, and the present invention is not limited to the liquid crystal compositions, liquid crystal elements, and the like. The components described in the claims are in no way limited to the components of 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, identical 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.

[0011] Liquid Crystal Composition The liquid crystal composition contains two or more chiral agents with different redox potentials. The chiral agents constituting the liquid crystal composition are configured to be capable of redox reactions and have a predetermined redox potential. A chiral agent having a predetermined redox potential may have, for example, a partial structure that serves as an asymmetry source and a redox moiety that is a partial structure capable of reversibly undergoing redox reactions. A redox-reactive chiral agent can reversibly exhibit, for example, ionic and nonionic properties in response to electrical stimulation. Such optically active, electrically responsive compounds can control the molecular arrangement of the helical structure of cholesteric liquid crystal in a liquid crystal composition (e.g., cholesteric liquid crystal) by electrical stimulation. This allows the period (pitch) of the helical structure formed by the cholesteric liquid crystal to be controlled, thereby controlling the wavelength of circularly polarized light selectively reflected by the cholesteric liquid crystal. Specifically, a longer pitch of the helical structure reflects longer wavelength light, while a shorter pitch reflects shorter wavelength light.

[0012] By including two or more chiral dopants having different redox potentials, the liquid crystal composition can exhibit different reflected colors at potentials corresponding to the redox potentials of the respective chiral dopants. That is, by enabling a multi-stage redox reaction in the liquid crystal composition due to potential changes, the helical pitch of the cholesteric liquid crystal can be changed in multiple stages, thereby modulating the reflected color in multiple stages.

[0013] The difference in oxidation-reduction potential between the chiral dopants contained in the liquid crystal composition may be, for example, 0.1 V or more and 3 V or less, and preferably 0.1 V or more and 2 V or less, as the absolute value of the difference in oxidation-reduction potential between the two chiral dopants. The oxidation-reduction potential of the chiral dopants can be measured, for example, by cyclic voltammetry (CV).

[0014] At least one chiral agent contained in the liquid crystal composition may have liquid crystallinity by itself to constitute the liquid crystal composition. The liquid crystal composition may further contain at least one liquid crystal compound in addition to the chiral agent. That is, the liquid crystal composition may contain a liquid crystal compound different from the chiral agent as a host liquid crystal, and 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 % to 10 mol %, and preferably 0.5 mol % to 5 mol %, relative to the liquid crystal compound. Specific examples of the chiral agent will be described in detail later.

[0015] 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.

[0016] 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, for example, the balance other than the chiral agent, the electrolyte, and additives contained as needed.

[0017] The liquid crystal composition may further contain an electrolyte. By including an electrolyte, sufficient conductivity can be imparted to the liquid crystal composition, the redox reaction of the chiral agent becomes easier, and the electrical stimulus response is further improved. 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 the field of electrochemistry (e.g., 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, relative to the liquid crystal compound.

[0018] 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.

[0019] The partial structure that serves as the source of asymmetry contained in the redox-reactive chiral agent includes, for example, an optically active skeleton having an asymmetric carbon, such as a binaphthyl skeleton. Furthermore, the partial structure that can undergo redox reactions includes, for example, ferrocene, ferrocene derivatives, and arylamine derivatives. The chiral agent may include a compound having a binaphthyl skeleton and a redox reaction site, and may include, for example, a compound represented by the following formula (1):

[0020]

[0021] In formula (1), R ０ each 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.

[0022] R ０Examples 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.

[0023] Each of s and t independently represents an integer of 0 to 6, and may preferably be an integer of 5 or less, or an integer of 2 or less, or may be an integer of 1 or more. Furthermore, each of p and q independently represents an integer of 0 to 6, and may preferably be an integer of 5 or less, or an integer of 2 or less, or may be an integer of 1 or more. Furthermore, p + s and q + t independently represent an integer of 0 to 6, and may preferably be an integer of 5 or less, or an integer of 2 or less, or may be an integer of 1 or more.

[0024] 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.

[0025] The hydrocarbon group as a 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.

[0026] The halogen atom as a 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.

[0027] 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.

[0028] 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, preferably 5 or less, or 3 or less.

[0029] 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 selected from the group consisting of A １The 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, 6 or less, or 3 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 bonding a carbonyl group and an oxygen atom, an amide bond, urea bond, urethane bond, or the like formed by bonding a carbonyl group and an imino group, or an ether bond formed by bonding an oxygen atom and an alkylene group. When a plurality of divalent linking groups represented by T are present in the compound represented by formula (1), they may be the same or different.

[0030] 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.

[0031] 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):

[0032]

[0033] In formulas (2a) and (2b), * indicates the bonding position to other atoms. １ , X２ 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—)—.

[0034] 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, preferably 6 or less, or 3 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

[0035] 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, or 3 or less. １ or Y ２ The substituents in １and R ２ The substituents are the same as those in

[0036] 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).

[0037]

[0038] 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).

[0039]

[0040] 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.

[0041] In one embodiment, the compound represented by formula (1) may be a compound represented by the following formula (1a):

[0042]

[0043] 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 ３ A 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.

[0044] 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, or 6 or less. １ The divalent aromatic group represented by the formula (1a) 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 compound represented by formula (1a), 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.

[0045] 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.

[0046] A ２ or A ３ The 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 the compound represented by formula (1a), A is the same as the aromatic hydrocarbon compound and the aromatic heterocyclic compound. 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.

[0047] 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.

[0048] 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 ３ The aromatic amino group substituting the aromatic group represented by formula (I) may be 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.

[0049] A １ , A ２and 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.

[0050] 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 (1a). 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 descriptions in, for example, WO 2024 / 096003 and PCT / JP2024 / 014082.

[0051] In one embodiment, the compound represented by formula (1) may be a compound represented by the following formula (1b):

[0052]

[0053] 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):

[0054]

[0055] In formula (3), R ７ , R ８ , R ９ , R １０ , R１１ , 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).

[0056] R ７ , R ８ , R ９ , R １０ , R １１ , R １２ , R １３ , R １４ or R １５ (Hereafter, collectively referred to as R ７ 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.

[0057] For the compound represented by formula (1b), reference can be made to the description in, for example, JP-A-2019-151597.

[0058] Liquid crystal element The liquid crystal element comprises a liquid crystal composition layer containing two or more chiral agents having different redox potentials, a counter electrode material layer containing a substance capable of undergoing a redox reaction, and a first electrode and a second electrode. The liquid crystal element may further comprise a reverse reaction suppression layer separating the liquid crystal composition layer and the counter electrode material layer, as necessary. The liquid crystal element may also comprise a pair of substrates that support the liquid crystal composition 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.

[0059] In a liquid crystal element having a liquid crystal composition layer and a counter electrode material layer containing chiral agents with different redox potentials, applying a voltage corresponding to the redox potential of each chiral agent causes the chiral agent to undergo a multi-stage redox reaction with 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 causing the wavelength of the selectively reflected circularly polarized light to change in multiple stages.

[0060] An example of the configuration of a liquid crystal element will now 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 liquid crystal composition layer 50 disposed on the counter electrode material layer 30, 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 first electrode 22 and the second electrode 24 are each connected to a power source.

[0061] 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 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. 2, 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 50 disposed in contact with the second electrode 24 are stacked with the reverse reaction suppression layer 40 interposed therebetween.

[0062] 3 is a schematic cross-sectional view showing another example of the configuration of a liquid crystal element. The liquid crystal element 300 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 liquid crystal composition layer 50. The reverse reaction suppression layer 40 is disposed extending on the side and top surfaces of the counter electrode material layer 30, separating the counter electrode material layer 30 disposed in contact with the first electrode 22 from the liquid crystal composition layer 50 disposed in contact with the second electrode 24. The liquid crystal composition layer 50 is disposed extending on the second electrode layer 24 and the reverse reaction suppression layer 40.

[0063] The liquid crystal composition layer is composed of a liquid crystal composition containing chiral agents having different redox potentials. Details of the liquid crystal composition are as described above. 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.

[0064] The counter electrode 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 undergoing a 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 (Sigma-Aldrich Co.) and the like.

[0065] The counter electrode layer may further contain a conductive material in addition to the counter electrode material, which is a substance capable of redox reaction. Examples of the conductive material include conductive polymers such as polystyrene sulfonate (PSS), polypyrrole, and polyaniline, and supporting electrolytes commonly used in the field of electrochemistry (e.g., nBu). ４ NPF ６ , nBu ４ NBF ４ , nBu ４ NClO ４ etc.) etc.

[0066] 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 Corporation) etc. In one embodiment, the counter electrode layer may be made of a composite of a substance capable of redox reaction and a conductive substance.

[0067] 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.

[0068] The liquid crystal element may further include a reverse reaction suppression layer separating the liquid crystal composition layer and the counter electrode material layer. In the liquid crystal element, when the applied voltage is removed, the chiral agent whose structure has changed due to the oxidation-reduction reaction returns to its original structure due to a reverse reaction, thereby restoring the period of the helical structure to its original state. By including the reverse reaction suppression layer in the liquid crystal element, the reverse reaction after the voltage is removed is suppressed, the period of the helical structure in the state when the voltage is applied is maintained, and the memory property of the reflected color is obtained. Here, the memory property of the reflected color means that the reflected color changed by the application of a voltage is maintained even after the application of the voltage is stopped. The maintenance time of the changed reflected color may be, for example, 3 seconds or more, or 30 seconds or more.

[0069] The reverse reaction suppression layer prevents 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 suppression layer may be configured to suppress contact between the chiral agent and the counter electrode material. For example, the reverse reaction suppression layer may be configured to suppress permeation of the chiral agent. The reverse reaction suppression layer may be made of a porous material or a non-porous material (e.g., a solid material). The reverse reaction suppression 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 suppression layer. Examples of resins that can form the reverse reaction suppression 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.

[0070] 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.

[0071] The electrode includes a first electrode disposed in contact with the counter electrode material layer and a second electrode disposed 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. Examples of the non-transparent electrode that can be used include a GC electrode.

[0072] 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.

[0073] The liquid crystal element may further include a pair of substrates, which may be arranged to hold, for example, a liquid crystal composition layer and a counter electrode material layer.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] As other aspects, the present invention may include use of the liquid crystal composition of the first aspect in the production of a liquid crystal device, and the liquid crystal composition of the first aspect used in a liquid crystal device.

[0078] The invention according to the present disclosure may include, for example, the following aspects: [1] A liquid crystal composition containing two or more chiral agents having different redox potentials.

[0079] [2] The liquid crystal composition according to [1], further comprising a liquid crystal compound.

[0080] [3] The liquid crystal composition according to [1] or [2], further comprising an electrolyte.

[0081] [4] The liquid crystal composition according to any one of [1] to [3], wherein the chiral agent includes a compound having a binaphthyl skeleton and a redox site.

[0082] [5] The liquid crystal composition according to any one of [1] to [4], wherein the chiral agent includes a compound represented by the following formula (1):

[0083] In formula (1), R ０ each 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.

[0084] [6] A liquid crystal element comprising: a liquid crystal composition layer containing two or more chiral agents having different redox potentials; a counter electrode material layer containing a substance capable of undergoing a redox reaction; and a first electrode and a second electrode.

[0085] [7] The liquid crystal element according to [6], comprising: the first electrode; a counter electrode material layer disposed on the first electrode; a liquid crystal composition layer disposed on the counter electrode material layer; and a second electrode disposed on the liquid crystal composition layer.

[0086] [8] The liquid crystal element according to [6] or [7], further comprising a reverse reaction suppression layer that suppresses a reverse reaction of the oxidation-reduction reaction of the chiral agent, the reverse reaction suppression layer separating the liquid crystal composition layer from the counter electrode material layer.

[0087] [9] The liquid crystal element according to any one of [6] to [8], wherein the liquid crystal composition layer further contains a liquid crystalline compound.

[0088]

[10] The liquid crystal element according to any one of [6] to [9], wherein the liquid crystal composition layer further contains an electrolyte.

[0089]

[11] The liquid crystal element according to any one of [6] to

[10] , wherein the chiral agent includes a compound having a binaphthyl skeleton and a redox site.

[0090]

[12] The liquid crystal element according to any one of [6] to

[11] , wherein the chiral agent contains a compound represented by the following formula (1):

[0091] In formula (1), R ０ each 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.

[0092]

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

[12] .

[0093] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0094] Reference Example As chiral dopants, BN-Fc, BN-TPA-OC6, BN-TPA-OMe, BN-TPA-tBu, and BN-TPA-Me represented by the following formulas were prepared. The chiral dopants were produced with reference to the description in JP-A-2019-151597.

[0095]

[0096] The redox potentials of the prepared chiral agents relative to ferrocene are shown in Table 1. The redox potentials of each chiral agent were determined by dissolving each chiral agent in 10 mL of dichloromethane to a total concentration of 1 mM, and further adding tetrabutylammonium tetrafluoroborate (TBABF ４ ) to a concentration of 100 mM. －１ The cyclic voltanogram was measured using ferrocene as the standard under the condition of 10 sweeps.

[0097]

[0098] Example 1 BN-Fc and BN-TPA-Me were mixed in a molar ratio of 1:1 and dissolved in 10 mL of dichloromethane to a concentration of 1 mM. ４ ) was dissolved to a concentration of 100 mM to prepare a composition containing two chiral dopants.

[0099] The obtained composition was subjected to a sweep rate of 0.1 Vsec. －１ Cyclic voltanograms were measured using ferrocene as the standard under the conditions of 10 sweeps, and the results are shown in Figure 4.

[0100] As shown in Figure 4, the composition containing two chiral dopants with different redox potentials exhibited a two-stage redox reaction. The redox potential of the composition in the first stage was 0.27 V, and the redox potential of the composition in the second stage was 0.57 V.

[0101] Example 2 A host liquid crystal was prepared by mixing 4-cyano-4'-pentyloxybiphenyl (5OCB) and 4-cyano-4'-pentylbiphenyl (5CB) in a molar ratio of 1:1. BN-Fc and BN-TPA-Me were dissolved as chiral agents at 1.5 mol %, respectively, and 1-ethyl-3-methylimidazolium trifluoromethylsulfonate (EMI.OTf) was dissolved as an electrolyte in the host liquid crystal at 3 mol %, to prepare a liquid crystal composition.

[0102] Using the liquid crystal composition obtained above, a liquid crystal device having the configuration shown in Figure 1 was fabricated. ITO glass was used as the substrate and electrodes. The liquid crystal composition was introduced into a cell having a cell thickness of 10 μm, which was made of ITO glass and on which a counter electrode layer had been formed by spin-coating PEDOT / PSS and Prussian blue nanoparticles.

[0103] The transmission spectrum of the fabricated liquid crystal element was measured before application of a DC voltage, when a DC voltage of 1.5 V was applied, and when a DC voltage of 2.5 V was applied. The results are shown in FIG.

[0104] The central wavelength of the reflection peak in the transmission spectrum in each state is also shown in Fig. 5. As shown in Fig. 5, it can be seen that the reflection peak wavelength changes in multiple stages depending on the applied voltage.

[0105] The disclosure of Japanese Patent Application No. 2023-119233 (filing date: July 21, 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 containing two or more chiral agents having different redox potentials.

2. The liquid crystal composition according to claim 1, further comprising a liquid crystal compound.

3. The liquid crystal composition according to claim 1 or 2, further comprising an electrolyte.

4. The liquid crystal composition according to any one of claims 1 to 3, wherein the chiral agent includes a compound having a binaphthyl skeleton and an oxidation-reduction site.

5. The liquid crystal composition according to any one of claims 1 to 4, wherein the chiral agent contains a compound represented by the following formula (1): (In formula (1), R ０ Each of R independently represents a functional group capable of undergoing an oxidation-reduction reaction. Each of s and t independently represents 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. 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. 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.

6. A liquid crystal element comprising a liquid crystal composition layer containing two or more chiral agents having different redox potentials, a counter electrode material layer containing a substance capable of undergoing an oxidation-reduction reaction, and a first electrode and a second electrode.

7. A liquid crystal element according to claim 6, comprising the first electrode, a counter electrode material layer disposed on the first electrode, a liquid crystal composition layer disposed on the counter electrode material layer, and a second electrode disposed on the liquid crystal composition layer.

8. A liquid crystal device according to claim 6 or 7, further comprising a reverse reaction suppression layer for suppressing a reverse reaction of the oxidation-reduction reaction of the chiral agent, said reverse reaction suppression layer separating said liquid crystal composition layer from said counter electrode material layer.

9. The liquid crystal device according to any one of claims 6 to 8, wherein the liquid crystal composition layer further contains a liquid crystalline compound.

10. The liquid crystal device according to any one of claims 6 to 9, wherein the liquid crystal composition layer further contains an electrolyte.

11. The liquid crystal device according to any one of claims 6 to 10, wherein the chiral agent includes a compound having a binaphthyl skeleton and a redox site.

12. The liquid crystal device according to any one of claims 6 to 11, wherein the chiral agent contains a compound represented by the following formula (1): (In formula (1), R ０ Each of R independently represents a functional group capable of undergoing an oxidation-reduction reaction. Each of s and t independently represents 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. 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. 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.

13. A display device or a light control device comprising a liquid crystal element according to any one of claims 6 to 12.

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