Liquid crystal composition and application thereof

Abstract

The invention discloses a liquid crystal composition and application thereof. The liquid crystal composition comprises at least one compound as shown in a formula I, at least one neutral compound component and at least one polar compound component. The liquid crystal composition has the advantages of being good in low-temperature solubility, high in contrast ratio, good in reliability after high-temperature-UV and excellent in direct current resistance, and can be used for manufacturing dimming films, dimming glass, liquid crystal display elements or liquid crystal displays and other products. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the technical field of liquid crystal display materials. More specifically, it relates to a liquid crystal composition and its application. Background Art

[0002] In the era of information display technology, liquid crystal display devices exhibit advantages such as flat panel display, light weight, low power consumption, and low driving voltage compared to other types of display devices. Therefore, they are widely used in fields such as calculators, instrumentation, computers, large flat panel displays, and projection TVs. Since liquid crystal molecules have a fixed dipole moment, by sandwiching a liquid crystal medium between two parallel glass substrates with many vertical and horizontal fine wires, after applying a voltage, the axes of the liquid crystal molecules move, thereby changing the arrangement direction of the liquid crystal molecules, and then refracting the light emitted by the backlight module to achieve the effect of generating a corresponding image. However, currently, liquid crystal display elements mainly generate images by using polarizing plates. Using a polarizing plate will cause approximately half of the light components to be absorbed by the polarizer, resulting in a reduction in light utilization efficiency. The guest-host liquid crystal doped with dichroic dyes can achieve electro-control of images and colors without a polarizing plate, showing a high light utilization efficiency. The principle of this liquid crystal is that a light-absorbing compound of dichroic dye is added to the liquid crystal host. Most dichroic dyes are rod-shaped, and visible light has different absorption effects in the long-axis and short-axis directions, so that the dye has optical anisotropy. When the vibration direction of the incident light is the same as the long-axis direction of the dye, the light is absorbed. When the vibration direction of the incident light is perpendicular to the long-axis direction of the dye, the light can pass through, so that the dye has two states: an absorption state and a non-absorption state in the liquid crystal device. By controlling the electric field voltage, the arrangement of the liquid crystal molecules changes accordingly, and the corresponding dye molecules change the light absorption intensity along with the orientation of the liquid crystal molecules, making the liquid crystal device exhibit variable transmittance and achieving dynamic dimming. As the core component of the guest-host liquid crystal, dichroic dyes have a decisive impact on the device performance.

[0003] Dichroic dyes include azo dyes, thiadiazole dyes, anthraquinone dyes, cyanine dyes, etc. Among them, azo dyes and thiadiazole dyes are the most widely used. Azo dyes have good solubility and high dichroic ratio, but poor reliability. They have strong molecular conjugation and are prone to fading and decomposition after long-term ultraviolet and high-temperature aging, which do not meet the usage requirements of scenarios such as vehicle-mounted and building curtain walls. Patent CN105377995A discloses benzothiadiazole and its derivative dyes for liquid crystals. Compared with the comparative perylene dye liquid crystals, they have improved anisotropy and solubility at 20 °C, and to a certain extent, improve the performance of display devices. Patent CN107580622A discloses benzothiadiazole quinoxaline dye liquid crystals, whose characteristic absorption band is relatively narrow and there is no band in the range of 500-550 nm, and can achieve significantly better color saturation. Patent CN113166652A simultaneously discloses benzothiadiazole and benzothiadiazole quinoxaline-based dye liquid crystals. The relevant examples have sufficient solubility (at 20 °C) and individually exhibit sufficient stability in the sunlight exposure experiment. However, the solubility of the relevant thiadiazole dye liquid crystals in the prior art at low temperatures, especially at -40 °C, is relatively insufficient, resulting in the precipitation of such thiadiazole dye liquid crystals at low temperatures, which leads to abnormal display of the display device and limits its application in extreme low-temperature scenarios such as outdoors or vehicle-mounted. Secondly, such dye liquid crystals also have relatively low contrast and still pose challenges in meeting market demands.

[0004] Dye liquid crystals have poor tolerance in a high-temperature - UV environment, that is, an environment where high temperature and UV coexist. In harsh application scenarios such as vehicle-mounted and building curtain walls, dye liquid crystal devices need to withstand high temperature and light simultaneously. The dye structure is mostly a large molecule with a high conjugated structure. High temperature - UV can synergistically break the chemical bonds of dye molecules, resulting in fading or color drift. The dye liquid crystals in the prior art have insufficient aging tolerance to high temperature - UV, and this is a key link in the research and development and production of dye liquid crystal devices, directly affecting the product life.

[0005] Dye liquid crystals have weak anti-DC ability. In the liquid crystal drive circuit, due to factors such as voltage, capacitance, and electromagnetic interference, the drive waveform will be distorted, and then a DC component will be generated. Charges will accumulate in the liquid crystal, accelerating the electrolytic corrosion and decomposition aging of the liquid crystal material, resulting in dye decomposition, making the color difference of the display device large and ultimately affecting normal display. The anti-DC characteristics of thiadiazole-based dye compositions in the prior art are relatively poor and are easily decomposed by DC components in the device. Developing an anti-DC dye composition is very important for the field of liquid crystal display technology. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a new technical solution that can improve or solve the above-mentioned problems. Specifically, the present invention provides a liquid crystal composition of a dichroic dye and its application. The liquid crystal composition is a liquid crystal composition of a dichroic dye, which has advantages such as good low-temperature solubility, high contrast, good post-reliability at high temperature-UV, and excellent DC resistance, and can be used to manufacture products such as dimming films, dimming glasses, liquid crystal display elements, or liquid crystal displays.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] On the one hand, the present invention provides a liquid crystal composition, which contains:

[0009] At least one compound represented by Formula I:

[0010] And

[0011] At least one neutral compound component and at least one polar compound component;

[0012] Wherein,

[0013] Each independently represents an aromatic ring, a heteroaromatic ring, or a fused ring, and any position thereof can be substituted by at least one L. L each independently represents -F, -Cl, a straight-chain, branched-chain, or cyclic alkyl group having 1 to 15 carbon atoms, wherein one or more non-adjacent -CH2- in the straight-chain, branched-chain, or cyclic alkyl group having 1 to 15 carbon atoms can be independently replaced by -CH=CH-, -O-, -CO-, -CO-O-, or -O-CO-, and one or more -H atoms can be independently replaced by -F or -Cl;

[0014] Represents

[0015] R1 and R2 are the same or different each time they appear and represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-connected -CH2- can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclopentenylidene, -CH=CH-, -N(R3)-, -O-, -S-, -CO-, -CO-O-, -O-CO- in a form where O- and S- are not connected to each other. Additionally, one or more H atoms can be replaced by F or Cl; wherein, at least one -CH2- in R1 and R2 is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, or cyclopentenylidene;

[0016] R a 、R b 、R c 、Rd 、R3, each occurrence being the same or different, represents -H, -F, -Cl, a straight-chain or branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, in addition, any one or more non-adjacent -CH2- groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO- in a form where O and S are not connected to each other, and wherein, in addition, one or more H atoms may be replaced by F or Cl;

[0017] m1 and m2 each independently represent 0 or 1.

[0018] In another aspect, the present invention provides the use of the liquid crystal composition as described in the first aspect above in the preparation of a dimming element.

[0019] The beneficial effects of the present invention are as follows:

[0020] The liquid crystal composition provided by the present invention is a liquid crystal composition of a benzothiadiazole and its derivative dichroic dye. This liquid crystal composition has the advantages of good low-temperature solubility, high contrast, good reliability after high temperature - UV, and excellent DC resistance, and can be used to manufacture products such as dimming films, dimming glasses, liquid crystal display elements, or liquid crystal displays. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following further describes in detail the specific embodiments of the present invention with reference to the accompanying drawings.

[0022] Figure 1 Shows the MS mass spectrum of the organic compound represented by Formula I-2-16.

[0023] Figure 2 Shows the MS mass spectrum of the organic compound represented by Formula I-1-2.

[0024] Figure 3 Shows the MS mass spectrum of the organic compound represented by Formula I-3-1.

[0025] Figure 4 Shows the MS mass spectrum of the organic compound represented by Formula I-2-1.

[0026] Figure 5 Shows the MS mass spectrum of the organic compound represented by Formula I-4-2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To more clearly illustrate the present invention, the following further describes the present invention with reference to preferred embodiments and the accompanying drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0028] According to a specific embodiment of the present invention, a liquid crystal composition is provided, which comprises:

[0029] At least one compound represented by Formula I:

[0030] And

[0031] At least one neutral compound component and at least one polar compound component;

[0032] Wherein,

[0033] Each independently represents an aromatic ring, a heteroaromatic ring, or a fused ring, and any position thereof may be substituted by at least one L, and each L independently represents -F, -Cl, a straight-chain, branched-chain, or cyclic alkyl group having 1 to 15 carbon atoms, wherein one or more non-adjacent -CH2- groups in the straight-chain, branched-chain, or cyclic alkyl group having 1 to 15 carbon atoms may be independently substituted by -CH=CH-, -O-, -CO-, -CO-O-, or -O-CO-, and one or more -H atoms may be independently substituted by -F or -Cl;

[0034] Represents

[0035] R1 and R2, each time they appear, are the same or different and represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein one or more non-connected -CH2- groups may be substituted by cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclopentenylidene, -CH=CH-, -N(R3)-, -O-, -S-, -CO-, -CO-O-, -O-CO- in a form where O- or S- are not connected to each other. Additionally, one or more H atoms may be substituted by F or Cl; wherein, at least one -CH2- in R1 and R2 is substituted by cyclopropylidene, cyclobutylidene, cyclopentylidene, or cyclopentenylidene;

[0036] R a 、R b 、R c 、R d 、R3, each time they appear, are the same or different and represent -H, -F, -Cl, a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, additionally, one or more non-connected -CH2- groups may be substituted by -O-, -S-, -CO-, -CO-O-, -O-CO- in a form where O- or S- are not connected to each other, and wherein, additionally, one or more H atoms may be substituted by F or Cl;

[0037] m1 and m2 each independently represent 0 or 1.

[0038] In some examples, the each independently represents 1,4-phenylene thiophene-2,5-diyl or thiophenothiophene-2,5-diyl where one or more H atoms may be replaced by the L.

[0039] In some examples, R1 and R2, each occurrence being the same or different, represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclopentenylidene, -N(R3)-, -O-, -CH═CH- in a form where the O atoms are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F; wherein at least one -CH2- in R1 and R2 is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentenylidene.

[0040] In some examples, the R a , R b , R c , R d , R3, each occurrence being the same or different, represents -H, a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms; wherein, additionally, one or more non-adjacent -CH2- may be replaced by O-, -CO-, -CO-O- or -O-CO- in a form where the O atoms are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F.

[0041] In some examples, the compound represented by Formula I is selected from the group consisting of the following compounds:

[0042]

[0043] wherein,

[0044] a represents 0, 1 or 2;

[0045] each occurrence being the same or different, represents

[0046] L, each occurrence being the same or different, represents -F, a straight-chain, branched-chain or cyclic alkyl group having 1 to 15 carbon atoms;

[0047] R1 and R2, each occurrence being the same or different, represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclopentenylidene, -N(R3)-, -O-, -CH=CH- in a form where the O atoms are not connected to each other, and wherein, additionally, one or more H atoms may be replaced by F, and wherein at least one -CH2- group in R1 and R2 is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentenylidene;

[0048] R a 、R b 、R c 、R d 、R3, each occurrence being the same or different, represents -H, a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, additionally, any one or more non-adjacent -CH2- groups may be replaced by -O- in a form where the O atoms are not connected to each other, and wherein, additionally, one or more H atoms may be replaced by F.

[0049] In some examples, a represents 0 or 1, each occurrence being the same or different, represents

[0050] L, each occurrence being the same or different, represents -F, a straight-chain, branched-chain or cyclic alkyl group having 1 to 15 carbon atoms;

[0051] R1 and R2, each occurrence being the same or different, represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclopentenylidene, -N(R3)-, -O-, -CH=CH- in a form where the O atoms are not connected to each other, and wherein, additionally, one or more H atoms may be replaced by F; wherein at least one -CH2- group in R1 and R2 is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentenylidene;

[0052] R a 、R b represents -H;

[0053] R c 、R d each occurrence being the same or different, represents -H, -F, a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms;

[0054] R3, each occurrence being the same or different, represents -H, a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms.

[0055] In the above examples, the end groups of the compounds represented by Formula I-1 to Formula I-5 all contain a cyclic structure, where:

[0056] The compound represented by Formula I-1 contains a thiadiazole and a biphenyl structure, and it is a dye with a color in the yellow range, and its color will shift slightly with the change of the end group;

[0057] The compound represented by Formula I-2 contains a thiadiazole and a symmetric thiophene ring structure, and it is a dye with a color in the red range, and its color will shift slightly with the change of the end group;

[0058] The compound represented by Formula I-3 contains a thiadiazoloquinoxaline and a symmetric thiophene ring structure, and it is a dye with a color in the green range, and its color will shift slightly with the change of the end group;

[0059] The compound represented by Formula I-4 contains a thiadiazole and a symmetric thiophenothiophene ring structure, and it is a dye in the blue range, and its color will shift slightly with the change of the end group;

[0060] The compound represented by Formula I-5 contains a thiadiazoloquinoxaline and a symmetric thiophenothiophene ring structure, and it is a blue-green dye, and its color will shift slightly with the change of the end group.

[0061] When the dye is actually applied, one or more dyes can be selected and combined according to the application scenario, without being restricted to the color and category of the dye.

[0062] In some examples, the compound represented by Formula I is selected from any one of the following compounds:

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074] In some preferred examples, the compound represented by Formula I is selected from any one of the following compounds:

[0075]

[0076]

[0077]

[0078]

[0079] In some examples, in the liquid crystal composition, by mass percentage, it contains 0.5-15 wt% of the compound represented by Formula I. In some more specific examples, it contains 2-15 wt% of the compound represented by Formula I.

[0080] In this embodiment, the compound represented by Formula I, its sub-formula compounds and intermediates can be prepared analogously to the methods known to those skilled in the art and described in standard works of organic chemistry (such as in Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Thieme-Verlag, Stuttgart).

[0081] In this embodiment, the monomer of the dye compound represented by Formula I mentioned is coupled with 2-thiopheneboronic acid through a bromide in the presence of a palladium-based catalyst, and then a boron ester is prepared with 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane through a butyllithium reagent at low temperature. The corresponding boron ester reacts with a dibromide through a Suzuki reaction to obtain the corresponding monobrominated product, and then the product is obtained through a secondary Suzuki reaction. More specifically, for example, the relevant dye monomers of benzothiadiazole and its derivatives can be prepared with reference to the similar synthesis methods in CN105377995A, and the relevant dye monomers of benzothiadiazoloquinoxaline and its derivatives can be prepared with reference to the similar synthesis methods in CN107580622A.

[0082] The MS mass spectra of the organic compounds represented by Formula I-1-2, Formula I-2-1, Formula I-2-16, Formula I-3-1, and Formula I-4-2 are as follows in sequence Figures 1 to 5 shown.

[0083] In some examples, the neutral component compound is selected from the compounds represented by Formula II:

[0084]

[0085] Among them,

[0086] rings B1 and B2 each independently represent

[0087]

[0088] R4 and R5 each independently represent an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, or -O-;

[0089] Z1 represents -CH2-CH2-, -O-, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH=CH-, -C≡C, or a single bond;

[0090] n1 and n2 each independently represent 0, 1, or 2.

[0091] In some examples, the compound represented by Formula II is selected from the group consisting of the compounds represented by Formula II-1 to Formula II-14:

[0092]

[0093] Among them,

[0094] R 41 and R 51 each independently represent an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, or -O-.

[0095] In some preferred examples, in the liquid crystal composition, by mass percentage, it contains 30 - 60% of neutral compounds.

[0096] In some specific examples, the mass percentage of the compound represented by Formula II includes but is not limited to 26.5%, 60%, 56%, 43%, etc.

[0097] In some examples, the polar component compound is selected from the compounds represented by Formula III:

[0098]

[0099] Among them,

[0100] R6 represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms; wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, or -O-;

[0101] R7 represents -F, -CF3, -OCF3 or -CN;

[0102] Z2 represents -CH2-CH2-, -O-, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -CH=CH-, -C≡C or a single bond;

[0103] X1 and X2 each independently represent H or F;

[0104] n3 and n4 each independently represent 1, 2, 3 or 4, and n4 represents 1 or 2;

[0105] each occurrence represents the same or different

[0106] In some specific examples, the compound represented by Formula III is selected from the group consisting of the compounds represented by Formula III-1 to Formula III-35:

[0107]

[0108]

[0109]

[0110] wherein, R 61 represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein any one or more non-adjacent -CH2- can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or -O-;

[0111] R 71 represents -F, -CF3, -OCF3 or -CN.

[0112] In some preferred examples, in the liquid crystal composition, by mass percentage, it contains 30-65% of the compound represented by Formula III. In some specific examples, the content of the compound represented by Formula III includes but is not limited to 40-65%, 40%, etc.

[0113] In some examples, the polar component compound is selected from the compounds represented by Formula IV:

[0114]

[0115] wherein,

[0116] each independently represents

[0117] R8 and R9 each independently represent an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or -O-;

[0118] Z3 and Z4 each independently represent -CH2-CH2-, -O-, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH=CH-, -C≡C- or a single bond;

[0119] X3 and X4 each independently represent -F or -CN;

[0120] n4 and n5 each independently represent 0, 1 or 2.

[0121] In some preferred examples, the compound represented by Formula IV is selected from the group consisting of the compounds represented by Formula IV-1 to Formula IV-29:

[0122]

[0123]

[0124] wherein, R 81 , R 91 each independently represent an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or -O-;

[0125] wherein, R7 and R8 each represent an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, and one or more non-adjacent -CH2- groups can be replaced by -O-, cyclopropyl, cyclobutyl or cyclopentyl.

[0126] In some preferred examples, in the liquid crystal composition, by mass percentage, it contains 2 wt% and 57 wt% of the compound represented by Formula IV.

[0127] In some examples, the polar component compound is selected from the compounds represented by Formula V:

[0128]

[0129] wherein, the rings each independently represent

[0130] wherein, R b , R cEach independently represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or -O-;

[0131] Z5 represents -CH2-CH2-, -O-, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH═CH-, -C≡C- or a single bond;

[0132] n6 and n7 each independently represent 0, 1 or 2.

[0133] In some preferred examples, the compound represented by Formula V is selected from the group consisting of the compounds represented by Formula V-1 to Formula V-4:

[0134]

[0135]

[0136] Wherein, R b1 , R c1 Each independently represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or -O-.

[0137] In some preferred examples, in the liquid crystal composition, by mass percentage, it contains 42 wt% of the compound represented by Formula V.

[0138] In some examples, the polar compound is the compound represented by Formula III, or the compound represented by Formula IV, or a mixture of the compound represented by Formula IV and the compound represented by Formula V.

[0139] Various functional dopants can also be added to the liquid crystal compound of the present invention. The content of the dopant is preferably between 0.005 and 1.0 wt%. These dopants can include, for example, antioxidants, ultraviolet absorbers, and chiral agents.

[0140] In the examples of the present invention, the structure of the exemplary ultraviolet absorber UV-P used is as follows, and the structure of the used sterically hindered phenolic antioxidant is as follows:

[0141] Ultraviolet absorber UV-P:

[0142]

[0143] Sterically hindered phenolic antioxidant:

[0144]

[0145] According to yet another specific embodiment of the present invention, there is provided an application of the liquid crystal composition as described above in the preparation of a dimming element.

[0146] In some examples, the dimming element is selected from a dimming film, dimming glass, a liquid crystal display element, or a liquid crystal display.

[0147] In this specification, unless otherwise specified, percentages are by mass percentage, temperature is in degrees Celsius (°C), and the specific meanings and test conditions of other symbols are as follows:

[0148] Cp represents the clearing point of the liquid crystal (°C), tested by DSC quantitative method;

[0149] Δn represents the optical anisotropy, no is the refractive index of the ordinary light, ne is the refractive index of the extraordinary light, and the test conditions are 25 ± 2 °C, 589 nm, tested by an Abbe refractometer;

[0150] Δε represents the dielectric anisotropy, Δε = ε∥ - ε⊥, where ε∥ is the dielectric constant parallel to the molecular axis and ε⊥ is the dielectric constant perpendicular to the molecular axis, and the test conditions are 25 ± 0.5 °C, 20 - micron parallel cell, tested by INSTEC: ALCT - IR1;

[0151] LTS represents the low - temperature stability, measured in the test unit.

[0152] Method for testing the maximum low - temperature solubility: After adding the dye compounds of the examples and comparative examples to different host liquid crystals at different concentrations (0.5 wt% - 5 wt%), heat and stir at 120 °C for 1 h, mix and stir evenly in a glass bottle, place it at - 40 °C for storage, and observe every day whether crystals precipitate. The concentration at which no precipitation occurs on the 20th day is the maximum solubility.

[0153] Method for testing the contrast at the maximum solubility: Add the dye compound of the above - mentioned maximum solubility of the example to the host liquid crystal as a test sample, add the dye compound D of the comparative example at the maximum solubility to the same host liquid crystal as a control sample, then use a TN - 7.0 - μm test cell to make a film, send it for DMS testing, test the voltage - transmittance curve from 380 nm to 800 nm at 0 V and 10 V voltages to obtain the transmittance at 0 V and 10 V, and calculate the contrast CR of the corresponding dye compound in the host liquid crystal at the maximum solubility according to the formula contrast = transmittance at 10 V / transmittance at 0 V.

[0154] Method for high - temperature - UV aging test: Conduct high - temperature - UV aging experimental tests on the dye compounds of the examples and comparative examples in the host liquid crystal. High - temperature - UV aging conditions: temperature 100 °C, use a UV LED lamp with a main wavelength of 365 nm, and its light intensity is 100 mw / cm 2, the aging time is 1000 h, and the test conditions for power consumption (power consumption current) after aging are 10 V and 32 Hz. The unit of power consumption is (μA).

[0155] Test method for DC resistance: Mix the examples and comparative examples with the host liquid crystal at the same concentration, pour the mixed liquid crystal into a TN - 7.0 μm test cell, apply 10 V DC voltage, and characterize the decomposition of the dye by measuring the color difference ΔE* of the test cell after 1000 h of power application to evaluate its DC resistance. Use the test instrument DMS - 501 (AUTRONIC MELCHERS, Germany) to measure the spectrum, determine the L*, a*, and b* values of the sample color, and calculate the color difference ΔE* through the formula in the Lab color space: ΔE* = [(ΔL*) 2 +(Δa*) 2 +(Δb*) 2 0.5 , where ΔL* represents the lightness difference, ΔL* = L* 最终 -L* 初始 , Δa* represents the red - green difference, Δa* = a* 最终 -a* 初始 , Δb* represents the yellow - blue difference, Δb* = b* 最终 -b* 初始 . The L*, a*, and b* values of the sample color are determined from the transmission curves of each spectrum (based on the CIE standard colorimetric system). L* represents lightness, a* represents red - green, and b* represents yellow - blue. The corresponding differences ΔL*, Δa*, and Δb* are determined based on the initial and final L*, a*, and b* of the sample.

[0156] Application Example

[0157] In order to test the corresponding properties of the compound shown in Formula I in the liquid crystal composition of the present invention in different host liquid crystals (including neutral compound components and polar compound components), the present invention provides the following applications.

[0158] The corresponding codes for the ring structure, end group, and linking group are shown in Tables 1 - 2.

[0159] Table 1 Corresponding Codes for Ring Structures

[0160]

[0161]

[0162] Table 2 Corresponding Codes for End Groups and Linking Groups

[0163]

[0164] Example:

[0165] ​ Its code is CC-Cp-V1;

[0166] Its code is PGP-Cpr1-2;

[0167] Its code is CPY-2-O2;

[0168] Its code is CCY-3-O2;

[0169] Its code is COY-3-O2;

[0170] Its code is CCOY-3-O2; Its code is Sb-CpO-O4;

[0171] Its code is Sc-CpO-O4;

[0172] Its code is CCU-3-F;

[0173] Its code is PGU-3-F;

[0174] Its code is CCPU-3-F;

[0175] Its code is CPGU-3-OT;

[0176] Its code is DGUQU-4-F; Its code is PGUQU-3-F;

[0177] Its code is PPGU-Cp-F.

[0178] The components and physical properties of the matrix liquid crystals SLC-1 to SLC-4 are shown in Tables 3 to 8.

[0179] Table 3 Composition and Physical Properties of Matrix Liquid Crystal SLC-1

[0180]

[0181] In the above table, the mass contents of components II and III are 100 wt%, the mass content of the ultraviolet absorber UV-P represents the ratio of its mass to the sum of the masses of components II and III, and the mass content of the sterically hindered phenolic antioxidant represents the ratio of its mass to the sum of the masses of components II and III. In the subsequent tables, the addition amounts of the dye compounds are also calculated based on the sum of the masses of components II and III.

[0182] Table 4 Composition and Physical Properties of Matrix Liquid Crystal SLC-2

[0183]

[0184]

[0185] In the above table, the mass contents of Components II and III are 100 wt%, the mass content of ultraviolet absorber UV-P represents the proportion of it in the sum of the masses of Components II and III, and the mass content of sterically hindered phenolic antioxidant represents the proportion of it in the sum of the masses of Components II and III. The addition amount of the subsequent dye compound is also calculated based on the sum of the masses of Components II and III.

[0186] Table 5 Composition and Physical Properties of Matrix Liquid Crystal SLC-3

[0187]

[0188] In the above table, the mass contents of Components II, IV, and V are 100 wt%, the mass content of ultraviolet absorber UV-P represents the proportion of it in the sum of the masses of Components II, IV, and V, and the mass content of sterically hindered phenolic antioxidant represents the proportion of it in the sum of the masses of Components II, IV, and V. The addition amount of the subsequent dye compound is also calculated based on the sum of the masses of Components II, IV, and V.

[0189] Table 6 Composition and Physical Properties of Matrix Liquid Crystal SLC-4

[0190]

[0191]

[0192] In the above table, the mass contents of Components II and IV are 100 wt%, the mass content of ultraviolet absorber UV-P represents the proportion of it in the sum of the masses of Components II and IV, and the mass content of sterically hindered phenolic antioxidant represents the proportion of it in the sum of the masses of Components II and IV. The addition amount of the subsequent dye compound is also calculated based on the sum of the masses of Components II and IV.

[0193] Table 7 Structures of Dye Compounds Involved in Examples and Comparative Examples

[0194]

[0195]

[0196]

[0197] Compared with the dye compound structures involved in the comparative examples, the main ring structures of the corresponding examples are the same as those of the comparative examples, and the structural difference from the comparative examples is only that the end groups contain cyclic structures (sub-cyclopropyl, sub-cyclobutyl, sub-cyclopentyl, or sub-cyclopentenyl).

[0198] High-temperature - UV aging test:

[0199] The dye compounds of the examples and comparative examples were subjected to high-temperature - UV aging experimental tests in the host liquid crystals SLC-1 and SLC-3. The high-temperature - UV aging conditions were as follows: temperature 100°C, using a UV LED lamp with a main wavelength of 365 nm and a light intensity of 100 mw / cm 2 , the aging time was 1000 h, and the test conditions for the power consumption (power consumption current) after aging were 10 V and 32 Hz. The unit of power consumption was (μA), and the power consumption change rate (%) = (power consumption after aging - initial power consumption) / initial power consumption. The results are shown in Tables 8 and 9.

[0200] Criterion for judging the power consumption change rate after high-temperature - UV aging: 0 ≤ power consumption change rate ≤ 20% is excellent, 20% < power consumption change rate ≤ 30% is good, 30 < power consumption change rate ≤ 50% is average, and power consumption change rate > 50% is poor. In actual test and verification, a power consumption change rate ≤ 30% is considered acceptable. Therefore, excellent and good in the power consumption change rate of this solution are OK.

[0201] Table 8 Related data of high-temperature - UV aging test

[0202]

[0203] Table 8 shows the high-temperature - UV aging test data of a mixed crystal composition using a single dye. From the power consumption test data, it can be found that under the condition of using the same concentration of dye monomers, compared with the comparative examples, the power consumption of the examples is significantly improved after 1000 h of high-temperature - UV aging, and the power consumption change rates are all below 30%. For the dye liquid crystals of type I-1 and I-2, the power consumption change rates are even below 20%. After high-temperature - UV aging treatment, the examples of the present invention show good power consumption changes in both the positive dielectric anisotropy host SLC-1 and the negative dielectric anisotropy host SLC-3, with good reliability and good stability under high-temperature - UV aging conditions.

[0204] Table 9 Related data of high-temperature - UV aging test

[0205]

[0206]

[0207] Table 9 shows the high-temperature - UV aging test data of the mixed crystal composition using more than two dyes. From the power consumption test data, it can be found that under the condition of using dyes with the same concentration, compared with the comparative examples, the power consumption of the examples is significantly improved after 1000h of high-temperature - UV aging. It should be noted that for Comparative Example 11-2, since it uses five dyes and the solubility of the comparative dyes used is poor, dye monomers have precipitated in the liquid crystal composition before the power consumption test at room temperature, so the relevant data of the high-temperature - UV aging test could not be completed. The examples of the present invention show good power consumption changes in both the positive dielectric anisotropy SLC-1 matrix and the negative dielectric anisotropy matrix SLC-3, with good reliability and good stability under high-temperature - UV aging conditions.

[0208] Solubility and contrast test:

[0209] Low-temperature solubility test: When testing the solubility of a single dye compound, the dye compounds of the examples and comparative examples were added to different matrix liquid crystals at different concentrations (0.5wt% - 5wt%), heated and stirred at 120°C for 1h, mixed and stirred evenly in a glass bottle, and stored at -40°C. Observe every day whether crystals precipitate, and the concentration at which no precipitation occurs on the 20th day is the maximum solubility. When testing the solubility comparison of more than two dyes, the examples and comparative examples need to add monomers of the same type and the same concentration, and the dissolution and low-temperature conditions are the same as those for evaluating a single dye compound.

[0210] Criterion for determining the maximum solubility: Since the low-temperature solubility of dye monomers in liquid crystals is generally 0.5wt% - 5wt%, in this solution, it is considered that when the low-temperature solubility of dye monomers increases by more than 1%, the increase is relatively obvious.

[0211] Contrast test at the maximum solubility: Add the thiazole dye compound with the maximum solubility of the present invention to the matrix liquid crystal as the test sample, add the thiazole dye compound D with the maximum solubility involved in the prior art to the same matrix liquid crystal as the control sample, then use a TN - 7.0μm test cell to dot the film, send it for DMS test, test the voltage - transmittance curve from 380nm to 800nm at 0V and 10V voltages to obtain the transmittance at 0V and 10V, and calculate the contrast CR of the corresponding dye compound in the matrix liquid crystal at the maximum solubility according to the formula contrast = transmittance at 10V / transmittance at 0V. When testing the contrast of more than two dyes, the examples and comparative examples need to add monomers of the same type and the same concentration.

[0212] Contrast determination criteria: When the contrast of the dye liquid crystal is between 1.00 and 1.20 (including the endpoints), an increase in contrast of more than 0.02 is considered to have a significant improvement; when the contrast of the dye liquid crystal is between 1.20 and 2.00 (excluding the endpoints), an increase in contrast of more than 0.05 is considered to have a significant improvement; when the contrast of the dye liquid crystal is between 2.00 and 4.00 (including the endpoints), an increase in contrast of more than 0.10 is considered to have a significant improvement.

[0213] Table 10 Related data of maximum low-temperature solubility and contrast test

[0214]

[0215] Table 10 shows the test data of the maximum solubility and contrast of the mixed crystal composition using one kind of dye. From the test data, it can be found that compared with the dye comparative example with the same main structure, the solubility of the examples has increased by more than 1%. Compared with Comparative Example 3, the solubility of Examples 3-1 and 3-2 has even increased by 2%. Compared with the comparative examples, the contrast of the examples at the maximum solubility has also been significantly improved. The examples of the present invention show good low-temperature solubility and contrast improvement in the positive dielectric anisotropy SLC-1 and SLC-2 matrices and the negative dielectric anisotropy matrices SLC-3 and SLC-4.

[0216] Table 11 Related data of low-temperature solubility and contrast test

[0217]

[0218]

[0219] Table 11 shows the test data of the low-temperature solubility and contrast of the mixed crystal composition using more than two kinds of dyes. From the test data, it can be found that compared with the dye comparative example with the same concentration and main structure, the contrast of the examples has been significantly improved. It should be noted that for Comparative Example 11-2, since it uses five kinds of dyes and the solubility of the comparative dye used is poor, it did not complete the low-temperature solubility experiment, and dye monomers had precipitated in the liquid crystal composition before the room-temperature contrast test, so it also failed to complete the relevant contrast test data. While for the corresponding Example 11-2, when the total dye concentration is 15 wt%, no precipitation occurred in 20 days at -40 °C, and the low-temperature solubility improvement is obvious. The examples of the present invention show good low-temperature solubility and contrast improvement in the positive dielectric anisotropy SLC-1 and SLC-2 matrices and the negative dielectric anisotropy matrices SLC-3 and SLC-4.

[0220] DC aging test

[0221] When using a single dye, the thiadiazole dye compounds of the examples and comparative examples were mixed with the parent liquid crystal at a concentration of 1 wt%, and the mixed crystal was poured into a TN-7.0 μm test cell. A DC voltage of 10 V was applied, and after aging for 1000 h, the color difference of the test sample was measured to characterize the DC resistance property of the dye. The smaller the color difference, the more stable the color of the sample after DC aging test, and the better the DC resistance effect. The results are shown in Table 10.

[0222] Criterion for judging color difference after DC aging: When the color difference of the dye-doped liquid crystal is in the range of 0 - 1.0 (including the endpoints), a reduction in color difference of more than 0.2 is considered a significant improvement; when the color difference of the dye-doped liquid crystal is in the range of 1.0 - 2.0 (excluding the endpoints), a reduction in color difference of more than 0.4 is considered a significant improvement; when the color difference of the dye-doped liquid crystal is in the range of 2.0 - 3.0 (including the endpoints), a reduction in color difference of more than 0.6 is considered a significant improvement.

[0223] Table 12 Relevant data for DC aging test

[0224]

[0225] Table 12 shows the relevant data of the color difference test after 1000 h of DC aging for the mixed crystal composition using a single dye. From the color difference test data, it can be found that under the condition of using the same concentration of dye monomers, compared with the comparative examples, the color difference of the examples is significantly improved after 1000 h of DC aging, proving that it can remain relatively stable under DC impact conditions and has excellent DC resistance effect. The examples of the present invention show good color difference improvement in both the SLC-1 parent liquid crystal with positive dielectric anisotropy and the SLC-3 parent liquid crystal with negative dielectric anisotropy.

[0226] Table 13 Relevant data for DC aging test

[0227]

[0228]

[0229] Table 13 shows the relevant data of the color difference test after 1000 h of DC aging for the mixed crystal composition using more than two dyes. From the color difference test data, it can be found that under the condition of using the same concentration of dye monomers, compared with the comparative examples, the color difference of the examples is significantly improved after 1000 h of DC aging, proving that it can remain relatively stable under DC impact conditions and has excellent DC resistance effect. It should be noted that for Comparative Example 11-2, since it used five dyes and the solubility of the comparative dye used was poor, dye monomers had precipitated in the liquid crystal composition before the DC aging experiment, so the color difference test data after DC aging could not be completed. The examples of the present invention show good color difference improvement in both the SLC-1 parent liquid crystal with positive dielectric anisotropy and the SLC-3 parent liquid crystal with negative dielectric anisotropy.

[0230] In summary, the present invention obtains a dichroic dye liquid crystal composition with good low-temperature solubility, high contrast, good high-temperature - UV post-reliability, and excellent DC resistance by compounding a compound of formula I with a neutral compound component and a polar compound component, and through the design of the end groups of the dye monomers and their synergy with the liquid crystal monomers. This composition can be used to manufacture products such as dimming films, dimming glasses, liquid crystal display elements, or liquid crystal displays.

[0231] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A liquid crystal composition, characterized in that, The liquid crystal composition contains: at least one compound represented by Formula I: and at least one neutral compound component and at least one polar compound component; wherein, Each independently represents an aromatic ring, a heteroaromatic ring, or a fused ring, where any position can be substituted by at least one L, and each L independently represents -F, -Cl, a straight-chain, branched-chain, or cyclic alkyl group having 1 to 15 carbon atoms, where one or more than two non-adjacent -CH2- groups in the straight-chain, branched-chain, or cyclic alkyl group having 1 to 15 carbon atoms can be independently substituted by -CH=CH-, -O-, -CO-, -CO-O-, or -O-CO-, and one or more -H atoms can be independently substituted by -F or -Cl; Indicate R1 and R2, each occurrence being the same or different, represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclopentenylidene, -CH=CH-, -N(R3)-, -O-, -S-, -CO-, -CO-O-, -O-CO- in a form where O- and S- are not connected to each other. Additionally, one or more H atoms can be replaced by F or Cl; wherein, at least one -CH2- in R1 and R2 is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentenylidene; R a 、R b 、R c 、R d 、R3, each occurrence being the same as or different from one another, represents -H, -F, -Cl, a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, additionally, any one or more non-adjacent -CH2- groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO- in a form where O and S are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F or Cl; m1 and m2 each independently represent 0 or 1.

2. The liquid crystal composition according to claim 1, characterized in that, The above-mentioned each independently represents 1,4-phenylene, thiophene-2,5-diyl or thienothiophene-2,5-diyl, wherein one or more H atoms may be replaced by the above-mentioned L; and / or R1 and R2, each occurrence being the same or different, represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclopentenylidene, -N(R3)-, -O-, -CH=CH- in a form where O- is not connected to each other, and wherein, additionally, one or more H atoms can be replaced by F; wherein, at least one -CH2- in R1 and R2 is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentenylidene; and / or Said R a , R b , R c , R d , and R3 each independently represents, each time it appears, -H, a linear or branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, additionally, one or more non-adjacent -CH2- groups may be replaced by -O-, -CO-, -CO-O- or -O-CO- in a form where the -O- groups are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F.

3. The liquid crystal composition according to claim 2, wherein the compound represented by Formula I is selected from the group consisting of the following compounds: wherein, a represents 0, 1 or 2; is the same or different each time it appears L, each occurrence being the same or different, represents -F, a straight-chain, branched-chain or cyclic alkyl group having 1 to 15 carbon atoms; R1 and R2, each occurrence being the same or different, represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclopentenylidene, -N(R3)-, -O-, -CH=CH- in a form where O- is not connected to each other, and wherein, additionally, one or more H atoms can be replaced by F, wherein, at least one -CH2- in R1 and R2 is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentenylidene; R a 、R b 、R c 、R d 、R3, each occurrence of which is the same as or different from the others, represents -H, a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, additionally, one or more non-adjacent -CH2- groups may be replaced by -O- in a form where the O atoms are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F.

4. The liquid crystal composition according to claim 3, characterized in that, wherein a represents 0 or 1, which represents the same or different each time it appears R1 and R2, each occurrence being the same or different, represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups can be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclopentenylidene, -N(R3)-, -O-, -CH=CH- in a form where O- is not connected to each other, and wherein, additionally, one or more H atoms can be replaced by F; wherein, at least one -CH2- in R1 and R2 is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentenylidene; R a 、R b represent -H; R c 、R d each, independently at each occurrence, represents -H, -F, a linear or branched alkyl or alkoxy group having 1 to 15 carbon atoms; R3, each occurrence being the same or different, represents -H, a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms.

5. The liquid crystal composition according to claim 4, characterized in that, The compound represented by Formula I is selected from any one of the following compounds:

6. The liquid crystal composition according to claim 1, characterized in that, The neutral compound component is selected from the compound represented by Formula II: wherein, Ring B1 and B2 each independently represent R4 and R5 each independently represent an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein any one or more non-consecutive -CH2- groups may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene, -O-; Z1 represents -CH2-CH2-, -O-, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH═CH-, -C≡C or a single bond; n1 and n2 each independently represent 0, 1 or 2.

7. The liquid crystal composition according to claim 1, characterized in that, The polar compound component is selected from the compounds represented by Formula III: Wherein, R6 represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms; wherein any one or more non-consecutive -CH2- groups may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or -O-; R7 represents -F, -CF3, -OCF3 or -CN; Z2 represents -CH2-CH2-, -O-, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -CH═CH-, -C≡C or a single bond; X1 and X2 each independently represent H or F; n3 and n4 each independently represent 1, 2, 3 or 4, and n4 represents 1 or 2; Represented the same or differently each time it appears 8. The liquid crystal composition according to claim 1, wherein The polar component compound is selected from the compounds represented by Formula IV: Wherein, Each independently represents R8 and R9 each independently represent an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein any one or more non-consecutive -CH2- groups may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or -O-; Z3 and Z4 each independently represent -CH2-CH2-, -O-, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH═CH-, -C≡C- or a single bond; X3 and X4 each independently represent -F or -CN; n4 and n5 each independently represent 0, 1 or 2.

9. The liquid crystal composition according to claim 8, wherein The polar component compound is selected from the compounds represented by Formula V: Among them, each ring independently represents Wherein, R b , R c each independently represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, wherein any one or more non-adjacent -CH2- may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or -O-; Z5 represents -CH2-CH2-, -O-, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH═CH-, -C≡C- or a single bond; n6 and n7 each independently represent 0, 1 or 2.

10. The liquid crystal composition according to any one of claims 1-9, characterized in that, In the liquid crystal composition, by mass percentage, it contains: 0.5 - 15% of the compound represented by Formula I; and / or 25 - 60% of a neutral compound; and / or 30 - 65% of a polar compound.

11. Use of the liquid crystal composition according to any one of claims 1 - 10 in the preparation of a dimming element.

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