A liquid crystal dimming device

Abstract

The present invention provides a liquid crystal dimming device. The dimming device of the present invention sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; the alignment directions of the upper alignment layer and the lower alignment layer are parallel alignments; the guest-host liquid crystal composition layer contains at least one dichroic dye, at least one chiral agent, and at least one liquid crystal composition; wherein, the liquid crystal composition contains at least one liquid crystal compound of general formula N. The liquid crystal dimming device of the present invention has appropriate transmittance (T r0 , T r255 ), appropriate contrast ratio, higher VHR (initial), higher VHR (Ra), and a wider temperature usage range. The dimming device of the present invention has a good display effect instantaneously after power-off for 2 h, and can effectively avoid the problems of display mura and image retention.

Description

Technical Field

[0001] The present invention belongs to the technical field of dimming devices, and relates to a liquid crystal dimming device. Background Art

[0002] At present, liquid crystal dimming devices are increasingly widely used in the fields of architecture and transportation. It is required that the liquid crystal dimming device has a wide temperature application range, especially at high temperatures, and can be used normally. In the existing intelligent dimming panel market, there are products such as Polymer Dispersed Liquid Crystal (PDLC) intelligent dimming devices and electrochromic intelligent dimming devices. The PDLC intelligent dimming device can only realize the switching between transparency and haze, without blocking light or heat insulation; the electrochromic intelligent dimming device has problems such as complex film layer process, long response time (8-20 s), and blueish dark state color. The guest-host liquid crystal dimming device utilizes the selective absorption of light by dichroic dye molecules in the liquid crystal to realize the switching between the bright state and the dark state. Compared with the existing PDLC and electrochromic intelligent dimming devices, it has greatly improved optical properties such as black state purity and response time.

[0003] The guest-host liquid crystal dimming device avoids the disadvantages of traditional modulation devices, ensures the optical display effect while achieving high-brightness display, and improves the service life. However, for the light modulation device prepared from the liquid crystal composition doped with dichroic dyes, there are still many technical problems to be solved. Generally, in order to increase the dark state transmittance of the guest-host liquid crystal dimming device and improve the contrast ratio, the concentration of dye molecules in the dye-liquid crystal mixture can be increased, or the cell thickness can be increased. However, when the concentration of dichroic dye molecules is relatively high, they will precipitate from the liquid crystal and affect the liquid crystal performance. Therefore, generally, the concentration of dye in the dye-liquid crystal molecules is limited. On the other hand, by improving the manufacturing process and increasing the liquid crystal cell thickness to improve the contrast ratio. However, the retardation amount (Δn×d) is usually fixed, so the liquid crystal display device with a larger cell thickness often makes the liquid crystal composition have a smaller optical anisotropy, and the smaller optical anisotropy often leads to a decrease in the contrast ratio.

[0004] On the other hand, in order to improve the contrast ratio of a single cell of dye-liquid crystal, a chiral agent is introduced into the dye-liquid crystal to increase the twist degree of liquid crystal molecules in the liquid crystal cell and reduce the P (steepness factor) value. In the initial state, the super-twisted negative liquid crystal is arranged perpendicular to the substrate. When an electric drive is applied, the negative liquid crystal molecules fall down and twist under the action of the chiral agent. The dye molecules twist along with the liquid crystal molecules, absorb light in multiple polarization directions, and exhibit a darker state with a lower transmittance, thereby increasing the contrast ratio. However, under the existing device structure, problems such as poor display, uneven alignment, display mura, and image retention still occur.

[0005] Image retention occurs because the liquid crystal is polarized by long-term driving, deflects, and is not controlled by the signal voltage, resulting in the same image being displayed on the screen for a period of time. This phenomenon weakens over time and finally disappears. Image retention can be divided into line retention and surface retention. Among them, line retention is highly related to the reliability of the liquid crystal material itself. The performance parameter often used to characterize the reliability of the liquid crystal material is the voltage holding ratio (VHR). The higher the VHR, the lower the possibility that the liquid crystal material is affected by interference factors (such as liquid crystal impurities, high and low temperatures, UV radiation, etc.).

[0006] How to solve the above problems is an urgent problem for those skilled in the art. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a liquid crystal dimming device, which has a high transmittance, good contrast, and high stability (VHR(initial), VHR(RA)), can effectively solve the problems of display mura and image retention of the dimming device, and meets the requirements of the temperature usage range in fields such as architecture and transportation.

[0008] To achieve the purpose of this invention, the following technical solutions are adopted in the present invention:

[0009] On the one hand, the present invention provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top;

[0010] The alignment directions of the upper alignment layer and the lower alignment layer are parallel alignments;

[0011] The guest-host liquid crystal composition layer contains at least one dichroic dye, at least one chiral agent, and at least one liquid crystal composition;

[0012] Among them, the liquid crystal composition contains at least one liquid crystal compound of general formula N:

[0013]

[0014] Among them,

[0015] R N1 and R N2 each independently represents a straight-chain or branched-chain alkyl group containing 1-12 (for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms, one or two or more non-adjacent -CH 2 - in the straight-chain or branched-chain alkyl group containing 1-12 carbon atoms can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O-, or -O-CO-;

[0016] Ring and the ring each independently represents wherein one or more -CH 2 - in may be replaced by -O-, and a single bond in one or more rings may be replaced by a double bond, wherein one or more -H in may be independently replaced by -F, -Cl or -CN respectively, and -CH= in one or more rings may be replaced by -N=;

[0017] Z N1 and Z N2 each independently represents a single bond, -CO-O-, -O-CO-, -CH 2 O-, -OCH 2 -, -CH=CH-, -C≡C-, -CH 2 CH 2 -, -CF 2 CF 2 -, -(CH 2 ) 4 -, -CF 2 O- or -OCF 2 -;

[0018] L N1 and L N2 each independently represents -H, a halogen, an alkyl group having 1 - 3 (e.g., 1, 2 or 3) carbon atoms, or an alkoxy group having 1 - 3 (e.g., 1, 2 or 3) carbon atoms; and

[0019] n N1 represents 0, 1, 2 or 3, n N2 represents 0 or 1, and 0 ≤ n N1 +n N2 ≤ 3, when n N1 = 2 or 3, the rings may be the same or different, and Z N1 may be the same or different.

[0020] In some embodiments of the present invention, the compounds of formula N are selected from the group consisting of the following compounds:

[0021]

[0022]

[0023]

[0024]

[0025] wherein R N1 and R N2 are the same as defined in General Formula N.

[0026] In some embodiments of the present invention, the compound of General Formula N accounts for 0.1% - 98% by weight of the liquid crystal composition (including any value or sub - range within this range), for example, 0.1%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, or the range between any two of these values.

[0027] In order to obtain better display effects and effectively avoid the problems of display mura and image retention, the compound of General Formula N is selected from the group consisting of the compounds of General Formula N - 2, the compounds of General Formula N - 5, and the compounds of General Formula N - 11.

[0028] In some embodiments of the present invention, preferably, R N1 and R N2 each independently represents a straight - chain or branched - chain alkyl group containing 1 - 10 carbon atoms, a straight - chain or branched - chain alkoxy group containing 1 - 9 carbon atoms, or a straight - chain or branched - chain alkenyl group containing 2 - 10 carbon atoms; more preferably, R N1 and R N2 each independently represents a straight - chain or branched - chain alkyl group containing 1 - 8 carbon atoms, a straight - chain or branched - chain alkoxy group containing 1 - 7 carbon atoms, or a straight - chain or branched - chain alkenyl group containing 2 - 8 carbon atoms; even more preferably, R N1 and R N2 each independently represents a straight - chain or branched - chain alkyl group containing 1 - 5 carbon atoms, a straight - chain or branched - chain alkoxy group containing 1 - 4 carbon atoms, or a straight - chain or branched - chain alkenyl group containing 2 - 5 carbon atoms.

[0029] In the present invention, the numerical range involved in defining the number of carbon atoms of the defined group means that the number of carbon atoms can be all selectable integers within the defined range. For example, 1 - 10 carbon atoms means that the number of carbon atoms can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and so on.

[0030] In some embodiments of the present invention, the dielectric anisotropy of the liquid crystal component is < 0 (for example, < -1, < -2, < -2, < -3, < -4, < -5, < -6).

[0031] In the present invention, when the alignment directions of the upper alignment layer and the lower alignment layer are parallel alignments, the twisting of liquid crystal molecules can be suppressed. In the powered state of the dimming device, reverse twisting is not likely to occur, enabling the super-twisted negative liquid crystal to have a better twisted state, making the liquid crystal dimming device of the present invention display more uniformly and effectively improving the problem of residual influence.

[0032] In some embodiments of the present invention, the dichroic dye molecule is selected from one or more dyes in the group consisting of azo, anthraquinone, phthalocyanine, cyanine, indigo, arylmethane, nitro, and nitroso.

[0033] In some embodiments of the present invention, the dichroic dye molecule is selected from the group consisting of azo and anthraquinone.

[0034] In the present invention, dichroic dyes exhibit different absorption characteristics for the visible light spectrum according to different structures. A single dichroic dye mainly absorbs light of a specific wavelength, and the color displayed is the complementary color of the light transmitted through all wavelengths. It is difficult to achieve black with a single dye. Therefore, multiple dyes need to be mixed to absorb light of multiple wavelengths, and then, according to the sensitivity of the human eye to light, uniform absorption in the visible light band is achieved, which is called black. For a liquid crystal dimming device containing dichroic dyes, in the visible light band, the more uniform the absorption of light of different wavelengths by the liquid crystal composition, the more uniform the distribution of the transmittance curve, and the better the display effect of the display device. Therefore, for the combination of multiple dichroic dyes, an appropriate ratio needs to be selected, and the chromaticity reproducibility is preferably good; in addition, when the liquid crystal composition and the dye have good mutual solubility, the higher the content of the dichroic dye that can be added, the higher the contrast.

[0035] In some embodiments of the present invention, the dichroic dye molecule is selected from the group consisting of the following compounds:

[0036]

[0037]

[0038]

[0039]

[0040] In some embodiments of the present invention, the weight percentage of the dichroic dye in the liquid crystal composition is 0.01% - 10% (including any value or sub-range within this range), for example, 0.1%, 0.5%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, or the range between any two of these values; preferably 1% - 6%.

[0041] In some embodiments of the present invention, the dichroic dye molecule is selected from one or a combination of at least two of the dyes numbered from dye No. 5 to dye No. 35, preferably a combination of one or at least two of the dyes numbered from dye No. 5 to dye No. 22.

[0042] In some embodiments of the present invention, the purple dye is selected from one or a combination of at least two of the dyes numbered from dye No. 5 to dye No. 9.

[0043] In some embodiments of the present invention, the orange dye is selected from one or a combination of at least two of the dyes numbered from dye No. 10 to dye No. 16.

[0044] In some embodiments of the present invention, the blue dye is selected from one or a combination of at least two of the dyes numbered from dye No. 17 to dye No. 35, preferably a combination of one or at least two of the dyes numbered from dye No. 17 to dye No. 22.

[0045] In some embodiments of the present invention, the liquid crystal composition further comprises at least one compound of general formula M:

[0046]

[0047] Wherein,

[0048] R M1 and R M2 each independently represents a straight-chain or branched-chain alkyl group containing 1 - 12 carbon atoms, one or more than two non-adjacent -CH 2 - in the straight-chain or branched-chain alkyl group containing 1 - 12 carbon atoms can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-;

[0049] ring Ring and ring each independently represents wherein one or more of the -CH 2 - can be replaced by -O-, and in one or more rings, a single bond can be replaced by a double bond, and at most one -H in can be replaced by a halogen;

[0050] Z M1 and Z M2 each independently represents a single bond, -CO-O-, -O-CO-, -CH 2 O-, -OCH 2 -, -C≡C-, -CH=CH-, -CH 2 CH 2 -, or -(CH 2 ) 4 -; and

[0051] n M represents 0, 1 or 2, wherein when n M = 2, the rings can be the same or different, and Z M2 can be the same or different.

[0052] The alkenyl group in the present invention is preferably selected from the groups represented by any one of the formulas (V1) to (V9), and particularly preferably the formula (V1), the formula (V2), the formula (V8) or the formula (V9). The groups represented by the formulas (V1) to (V9) are shown as follows:

[0053]

[0054] wherein, * represents a carbon atom in the ring structure to which it is bonded.

[0055] The alkenyloxy group in the present invention is preferably selected from the groups represented by any one of the formulas (OV1) to (OV9), and particularly preferably the formula (OV1), the formula (OV2), the formula (OV8) or the formula (OV9). The groups represented by the formulas (OV1) to (OV9) are shown as follows:

[0056]

[0057]

[0058] wherein, * represents a carbon atom in the ring structure to which it is bonded.

[0059] In some embodiments of the present invention, the compound of the general formula M is selected from the group consisting of the following compounds:

[0060]

[0061] and

[0062] wherein R M1 and R M2 are the same as defined in general formula M.

[0063] In some embodiments of the present invention, the compound of general formula M accounts for 0.1% - 60% (including any value or sub-range within this range) by weight of the liquid crystal composition, such as 0.1%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, or the range between any two of these values; preferably, the compound of general formula M accounts for 1% - 50% by weight of the liquid crystal composition.

[0064] In some embodiments of the present invention, in order to obtain better display effects and effectively avoid the problems of display mura and image retention, the compound of general formula M is selected from the group consisting of compounds of general formula M-1, compounds of general formula M-2, compounds of general formula M-12, compounds of general formula M-16, compounds of general formula M-26, compounds of general formula M-27, compounds of general formula M-28, compounds of general formula M-29, compounds of general formula M-30, compounds of general formula M-31, compounds of general formula M-32, compounds of general formula M-33.

[0065] In some embodiments of the present invention, in order to obtain better display effects (higher VHR (initial), higher VHR (Ra) and a wider temperature usage range) and effectively avoid the problems of display mura and image retention, the compound of general formula M comprises at least one compound selected from the group consisting of compounds of general formula M-26, compounds of general formula M-27, compounds of general formula M-28, compounds of general formula M-29, compounds of general formula M-30, compounds of general formula M-31, compounds of general formula M-32, compounds of general formula M-33.

[0066] In some embodiments of the present invention, R M1 and R M2Preferably, each is independently a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms, a straight-chain or branched-chain alkoxy group having 1 to 9 carbon atoms, or a straight-chain or branched-chain alkenyl group having 2 to 10 carbon atoms; R M1 and R M2 More preferably, each is independently a straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms, a straight-chain or branched-chain alkoxy group having 1 to 7 carbon atoms, or a straight-chain or branched-chain alkenyl group having 2 to 8 carbon atoms; R M1 and R M2 Even more preferably, each is independently a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms, a straight-chain or branched-chain alkoxy group having 1 to 4 carbon atoms, or a straight-chain or branched-chain alkenyl group having 2 to 5 carbon atoms.

[0067] In some embodiments of the present invention, R M1 and R M2 are preferably each independently a straight-chain alkenyl group having 2 to 8 carbon atoms; more preferably each is independently a straight-chain alkenyl group having 2 to 5 carbon atoms.

[0068] In some embodiments of the present invention, preferably, any one of R M1 and R M2 is a straight-chain alkenyl group having 2 to 5 carbon atoms, and the other is a straight-chain alkyl group having 1 to 5 carbon atoms.

[0069] In some embodiments of the present invention, R M1 and R M2 are preferably each independently a straight-chain alkyl group having 1 to 8 carbon atoms, or a straight-chain alkoxy group having 1 to 7 carbon atoms; more preferably each is independently a straight-chain alkyl group having 1 to 5 carbon atoms, or a straight-chain alkoxy group having 1 to 4 carbon atoms.

[0070] In some embodiments of the present invention, preferably, any one of R M1 and R M2 is a straight-chain alkyl group having 1 to 5 carbon atoms, and the other is a straight-chain alkyl group having 1 to 5 carbon atoms, or a straight-chain alkoxy group having 1 to 4 carbon atoms; more preferably, R M1 and R M2 are both each independently a straight-chain alkyl group having 1 to 5 carbon atoms.

[0071] In some embodiments of the present invention, when reliability is emphasized, it is preferred that R M1 and R M2 are both alkyl groups; when reducing the volatility of the compound is emphasized, it is preferred that R M1 and R M2are all alkoxy groups; when reducing viscosity is emphasized, R is preferably M1 and R M2 at least one of them is an alkenyl group.

[0072] In some embodiments of the present invention, the liquid crystal composition further comprises at least one compound of general formula A-1 and / or general formula A-2:

[0073]

[0074] wherein,

[0075] R A1 and R A2 each independently represents a straight-chain or branched-chain alkyl group containing 1-12 carbon atoms, one or more non-adjacent -CH 2 - in the straight-chain or branched-chain alkyl group containing 1-12 carbon atoms can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-, and one or more -H in the straight-chain or branched-chain alkyl group containing 1-12 carbon atoms can be independently replaced by -F or -Cl;

[0076] Ring Ring Ring and Ring each independently represents wherein one or more -CH 2 - can be replaced by -O-, one or more single bonds in the ring can be replaced by double bonds, and one or more -H in can be independently replaced by -F, -Cl or -CN, and one or more -CH= in the ring can be replaced by -N=;

[0077] Z A11 、Z A21 and Z A22 each independently represents a single bond, -CH 2 CH 2 -, -CF 2 CF 2 -, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH-, -CF=CF-, -CH 2 O- or -OCH 2 -;

[0078] L A11 、L A12 、LA13 , L A21 and L A22 each independently represents -H, an alkyl group having 1 to 3 carbon atoms, or a halogen;

[0079] X A1 and X A2 each independently represents a halogen, a haloalkyl group or a haloalkoxy group having 1 to 5 carbon atoms, a haloalkenyl group or a haloalkenyloxy group having 2 to 5 carbon atoms;

[0080] n A11 represents 0, 1, 2, or 3. When n A11 = 2 or 3, the rings may be the same or different, and Z A11 may be the same or different;

[0081] n A12 represents 1 or 2, where when n A12 = 2, the rings may be the same or different; and

[0082] n A2 represents 0, 1, 2, or 3, where when n A2 = 2 or 3, the rings may be the same or different, and Z A21 may be the same or different.

[0083] In some embodiments of the present invention, the weight percentage of at least one compound of general formula A-1 and / or general formula A-2 in the liquid crystal composition is 0.1% - 60% (including any value or sub-range within this range), such as 0.1%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, or the range between any two of these values.

[0084] In some embodiments of the present invention, the compounds of general formula A-1 are selected from the group consisting of the following compounds:

[0085]

[0086]

[0087] and

[0088] Wherein,

[0089] R A1 represents a straight-chain or branched alkyl group having 1 to 8 carbon atoms, and one or more than two non-adjacent -CH 2 - in the straight-chain or branched alkyl group having 1 to 8 carbon atoms can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-, and one or more -H in the straight-chain or branched alkyl group having 1 to 8 carbon atoms can be independently replaced by -F or -Cl;

[0090] R v and R w each independently represents -CH 2 - or -O-;

[0091] L A11 、L A12 、L A11 ’, L A12 ’, L A14 、L A15 and L A16 each independently represents -H or -F;

[0092] L A13 and L A13 ’ each independently represents -H or -CH 3 ;

[0093] X A1 represents -F, -CF 3 or -OCF 3 ; and

[0094] v and w each independently represent 0 or 1.

[0095] In some embodiments of the present invention, the weight percentage of the compound of general formula A-1 in the liquid crystal composition is 0.1% - 50% (including any value or sub-range within this range), such as 0.1%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, or the range between any two of these values.

[0096] In some embodiments of the present invention, the compounds of general formula A-2 are selected from the group consisting of the following compounds:

[0097]

[0098] and

[0099] wherein

[0100] R A2 represents a straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms, and one or two or more non-adjacent -CH 2 - in the straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms may be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-, and one or more -H in the straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms may be independently replaced by -F or -Cl;

[0101] L A21 L A22 L A23 L A24 and L A25 each independently represents -H or -F; and

[0102] X A2 represents -F, -CF 3 -OCF 3 or -CH 2 CH 2 CH=CF 2 .

[0103] In some embodiments of the present invention, the compound of general formula A-2 accounts for 0.1% - 50% by weight of the liquid crystal composition (including any value or sub-range within this range), such as 0.1%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, or the range between any two of these values.

[0104] In some embodiments of the present invention, the liquid crystal composition further comprises at least one compound of general formula F:

[0105]

[0106] wherein

[0107] R F1 and R F2each independently represents -H, a halogen, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkyl group having 1 to 12 carbon atoms, one or two or more non-adjacent -CH 2 - can be independently replaced by -C≡C-, -O-, -S-, -CO-, -CO-O- or -O-CO-, and one or more -H in the linear or branched alkyl group having 1 to 12 carbon atoms can be independently replaced by -F or -Cl;

[0108] ring and ring each independently represents wherein one or more -CH 2 - can be replaced by -O-, and one or more single bonds in the ring can be replaced by double bonds, wherein one or more -H therein can be independently replaced by -CN, -F or -Cl, and one or more -CH= in the ring can be replaced by -N=;

[0109] X F represents -O-, -S- or -CO-; L F1 and L F2 each independently represents -H, -F, -Cl, -CF 3 or -OCF 3 ;

[0110] Z F1 and Z F2 each independently represents a single bond, -O-, -CO-O-, -O-CO-, -CH 2 O-, -OCH 2 -, -CH=CH-, -C≡C-, -CH 2 CH 2 -, -CF 2 CF 2 -, -(CH 2 ) 4 -, -CF 2 O- or -OCF 2 -;

[0111] n F1 and n F2 each independently represents 0, 1 or 2, wherein when n F1 represents 2, the rings can be the same or different, wherein when n F2 represents 2, the rings can be the same or different, ZF2 may be the same or different; and

[0112] n F4 represents an integer from 0 to 4.

[0113] In some embodiments of the present invention, the compound of general formula F is selected from the group consisting of the following compounds:

[0114]

[0115]

[0116]

[0117] and

[0118] wherein,

[0119] R F2 ' represents a straight-chain or branched alkoxy group containing 1 to 11 carbon atoms;

[0120] X F1 and X F2 each independently represents -CH 2 - or -O-;

[0121] n F3 represents an integer from 1 to 5 (such as 1, 2, 3, 4 or 5); and

[0122] R F3 represents a straight-chain or branched alkyl group containing 1 to 5 carbon atoms, or a straight-chain or branched alkoxy group containing 1 to 4 carbon atoms, or a straight-chain or branched alkenyl group containing 2 to 5 carbon atoms.

[0123] In some embodiments of the present invention, the compound of general formula F accounts for 0.1% - 30% by weight of the liquid crystal composition (including any value or sub-range within this range), for example, 0.1%, 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, or the range between any two of these values.

[0124] In some embodiments of the present invention, the liquid crystal composition further comprises at least one polymerizable compound of general formula RM:

[0125]

[0126] Among them,

[0127] ring and ring each independently represent wherein one or more -CH 2 - in it can be replaced by -O-, and the single bond in one or more rings can be replaced by a double bond, wherein one or more -H in it can be independently replaced by -F, -Cl, -CN, -Sp 3 -P 3 , a halogenated or unhalogenated straight-chain alkyl group having 1 to 12 carbon atoms, a halogenated or unhalogenated straight-chain alkoxy group having 1 to 11 carbon atoms, substituted, and -CH= in one or more rings can be replaced by -N=;

[0128] ring represents wherein one or more -H in it can be independently replaced by -F, -Cl, -CN, -Sp 3 -P 3 , a halogenated or unhalogenated straight-chain alkyl group having 1 to 12 carbon atoms, a halogenated or unhalogenated straight-chain alkoxy group having 1 to 11 carbon atoms, substituted, and -CH= in one or more rings can be replaced by -N=;

[0129] R 1 represents -H, halogen, -CN, -Sp 2 -P 2 , a straight-chain or branched-chain alkyl group having 1 to 12 (for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12) carbon atoms, wherein the straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms, one or two or more non-adjacent -CH 2 - in it can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-, and one or more -H can be independently replaced by -F or -Cl;

[0130] P 1 、P 2 and P 3 each independently represent polymerizable groups;

[0131] Sp 1 、Sp 2 and Sp 3each independently represents a spacer group or a single bond;

[0132] X 0 represents -O-, -S- or -CO-;

[0133] Z 1 and Z 2 each independently represents -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH 2 O-, -OCH 2 -, -CH 2 S-, -SCH 2 -, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -(CH 2 ) d -, -CF 2 CH 2 -, -CH 2 CF 2 -, -(CF 2 ) d -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH 2 CH 2 -CO-O-, -O-CO-CH 2 CH 2 -, -CHR 1 -, -CR 1 R 2 -, or a single bond, where R 1 and R 2 each independently represents a straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms, and d represents an integer from 1 to 4; and

[0134] a represents 0, 1 or 2, b represents 0 or 1, where when a represents 2, the rings can be the same or different, and Z 1 can be the same or different.

[0135] In some embodiments of the present invention, the polymerizable compound of the general formula RM is selected from the group consisting of the following compounds:

[0136]

[0137]

[0138]

[0139] and

[0140] wherein

[0141] X 1 -X 10 and X 12 each independently represents -F, -Cl, -Sp 3 -P 3 , a straight-chain alkyl or alkoxy group having 1 to 5 carbon atoms,

[0142] In some embodiments of the present invention, X 1 -X 10 and X 12 each independently represents -F, -Cl, -Sp 3 -P 3 , -CH 3 , or -OCH 3 .

[0143] In some embodiments of the present invention, Sp 1 and Sp 2 both represent a single bond.

[0144] The polymerizable groups involved in the present invention are groups suitable for polymerization reactions (e.g., free radical or ionic polymerization, addition polymerization or condensation polymerization), or groups suitable for addition or condensation on the polymer backbone. For chain polymerization, polymerizable groups containing -CH=CH- or -C≡C- are particularly preferred; for ring-opening polymerization, oxetanyl or epoxy groups are particularly preferred, for example.

[0145] In some embodiments of the present invention, the polymerizable groups P 1 , P 2 , P 3 each independently represents or -SH; preferably, the polymerizable groups P 1 , P 2 , P 3 each independently represents or -SH; more preferably, the polymerizable groups P 1 , P 2 , P 3 each independently represents

[0146] As used herein, the term "spacer group" is known to those skilled in the art and is described in the literature (e.g., Pure Appl.Chem.2001,73(5),888 and C.Tschierske,G.Pelzl,S.Diele,Angew.Chem.2004,116,6340-6368). As used herein, the term "spacer group" refers to a flexible group that connects a mesogenic group and a polymerizable group in a polymerizable compound. Typical spacer groups are, for example, -(CH 2 )p 1 -, -(CH 2 CH 2 O)q 1 -CH 2 CH 2 -,-(CH 2 CH 2 S)q 1 -CH 2 CH 2 -,-(CH 2 CH 2 NH)q 1 -CH 2 CH 2 -,-CR 0 R 00 -(CH 2 ) p1 - or -(SiR 0 R 00 -O)p 1 -, where p 1 represents an integer from 1 to 12 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12), q 1 represents an integer from 1 to 3 (e.g., 1, 2, or 3), and R 0 and R 00 each independently represent -H, a straight-chain or branched-chain alkyl group containing 1 to 12 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms, or a cycloalkyl group containing 3 to 12 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms. Particularly preferred spacer groups are -(CH 2 )p 1 -,-(CH 2 )p 1 -O-,-(CH 2 )p 1 -O-CO-,-(CH 2 )p 1 -CO-O-,-(CH 2 )p 1-O-CO-O- or -CR 0 R 00 -(CH 2 ) p1 -.

[0147] In some embodiments of the present invention, the weight percentage of the polymerizable compound of the general formula RM in the liquid crystal composition is 0.001% - 5% (including any value or sub-range within this range), for example, 0.001%, 0.002%, 0.004%, 0.005%, 0.006%, 0.008%, 0.01%, 0.02%, 0.04%, 0.06%, 0.08%, 0.1%, 0.2%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.32%, 0.33%, 0.34%, 0.35%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.6%, 1.8%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or the range between any two of these values.

[0148] In some embodiments of the present invention, the liquid crystal composition further comprises at least one self-aligning agent of the general formula SA:

[0149]

[0150] wherein,

[0151] R S1 represents -Sp 1 -P 1 a straight-chain or branched-chain alkyl group containing 1 - 12 (for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12) carbon atoms, where one or two or more non-adjacent -CH 2 - in the straight-chain or branched-chain alkyl group containing 1 - 12 carbon atoms can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-, and the straight-chain or branched-chain alkyl group containing 1 - 12 carbon atoms, one or more -H in it can be independently replaced by -F or -Cl;

[0152] ring represents wherein one or more -CH 2 - can be replaced by -O-, and one or more single bonds in the ring can be replaced by double bonds;

[0153] Ls 1 and Ls 3each independently represents -F, -Cl, -CN, -NO 2 , -NCO, -NCS, -OCN, -SCN, -C(O)N(R S0 ) 2 , -C(O)R S0 , a straight-chain or branched alkyl group containing 1 - 12 (for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms, wherein one or more non-adjacent -CH in the straight-chain or branched alkyl group containing 1 - 12 carbon atoms 2 - can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-, and the straight-chain or branched alkyl group containing 1 - 12 carbon atoms, one or more -H in can be independently replaced by -F, where R S0 represents a straight-chain or branched alkyl group containing 1 - 12 (for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms;

[0154] Ls 2 represents -Sp 3 -P 2 or

[0155] R S2 and R S3 each independently represents an anchoring group, and the anchoring group is where * represents the connection site in the structure to which it is bonded;

[0156] p represents 1 or 2, and when p represents 2, -Sp 8 -X 2 can be the same or different;

[0157] o represents 0 or 1;

[0158] M S1 represents

[0159] I S1 and J S1 each independently represents -CH 2 -, -O- or -S-;

[0160] N S1 represents =O or =S;

[0161] V K1 、V K2 and VK3 each independently represents -CH= or -N=;

[0162] X 1 and X 2 each independently represents -H, -OH, -SH, -NH 2 , -NHR 11 , -N(R 11 ) 2 , -NHC(O)R 11 , -OR 11 , -C(O)OH, -CHO, or a straight-chain or branched-chain halogenated or unhalogenated alkyl group having 1 - 12 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms, wherein at least one of X 1 and X 2 is selected from the group consisting of -OH, -SH, -NH 2 , -NHR 11 , -C(O)OH, and -CHO, and wherein R 11 represents a straight-chain or branched-chain alkyl group having 1 - 12 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms;

[0163] P 1 , P 2 and P 3 each independently represents a polymerizable group;

[0164] Sp 1 , Sp 2 , Sp 3 , Sp 4 , Sp 5 , Sp 7 and Sp 8 each independently represents a spacer group or a single bond;

[0165] Sp 6 each independently represents

[0166] Z 1 and Z 2 each independently represents -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH 2 O-, -OCH 2 -, -CH 2 S-, -SCH 2 -, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -,-(CH2 ) d -, -CF 2 CH 2 -, -CH 2 CF 2 -, -(CF 2 ) d -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH 2 CH 2 -CO-O-, -O-CO-CH 2 CH 2 -, -CHR 1 -, -CR 1 R 2 - or a single bond, where R 1 and R 2 each independently represent a straight-chain or branched-chain alkyl group containing 1 - 12 carbon atoms, and d represents an integer from 1 to 4;

[0167] n s1 represents 1, 2 or 3, n s2 represents 1, 2, 3 or 4, and n s1 +n s2 ≥3, where when n s1 represents 2 or 3, can be the same or different, where when n s2 represents 2, 3 or 4, can be the same or different; and

[0168] p s1 、p s2 、p s3 and p s4 each independently represent 0, 1 or 2, where when p s1 represents 2, Ls 2 can be the same or different, where when p s2 represents 2, Ls 1 can be the same or different; where when p s3 represents 2, -Sp 5 -R S3 can be the same or different; where when p s4 represents 2, Ls 3 can be the same or different.

[0169] In some embodiments of the present invention, Ls 2 represents -Sp 3 -P 2 、

[0170] In some embodiments of the present invention, Sp 3 , Sp 4 and Sp 5 each independently represents -(CH 2 )p 1 -, -(CH 2 )p 1 -O-, -(CH 2 )p 1 -O-CO-, -(CH 2 )p 1 -CO-O-, -(CH 2 )p 1 -O-CO-O- or -CR 0 R 00 -(CH 2 ) p1 -, where p 1 represents an integer from 1 to 12 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12), and R 0 and R 00 each independently represents -H or a straight-chain or branched-chain alkyl group containing 1 to 12 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms, or a cycloalkyl group containing 3 to 12 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms; preferably, Sp 3 , Sp 4 and Sp 5 each independently represents -(CH 2 )p 1 - or -(CH 2 )p 1 -O-.

[0171] In some embodiments of the present invention, the self-aligning agent of general formula SA is selected from the group consisting of the following compounds:

[0172]

[0173]

[0174]

[0175]

[0176] and

[0177]

[0178] wherein,

[0179] Ls 31 Represents -F, -Cl, -CN, -NO 2 , -NCO, -NCS, -OCN, -SCN, -C(O)N(R S0 ) 2 , -C(O)R S0 , a straight-chain or branched alkyl group containing 1-12 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms, wherein one or more than two non-adjacent -CH in the straight-chain or branched alkyl group containing 1-12 carbon atoms 2 - can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O-, or -O-CO-, and the straight-chain or branched alkyl group containing 1-12 carbon atoms, one or more -H in can be independently replaced by -F, where R S0 represents a straight-chain or branched alkyl group containing 1-12 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms;

[0180] Ls 21 represents -Sp 3 -P 2 or and

[0181] Z 11 represents -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH 2 O-, -OCH 2 -, -CH 2 S-, -SCH 2 -, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -(CH 2 ) d -, -CF 2 CH 2 -, -CH 2 CF 2 -, -(CF 2 ) d -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH 2 CH 2-CO-O-, -O-CO-CH 2 CH 2 -, -CHR 1 -, -CR 1 R 2 -, or a single bond, where R 1 and R 2 each independently represent a straight-chain or branched alkyl group containing 1 to 12 carbon atoms, and d represents an integer from 1 to 4.

[0182] In some embodiments of the present invention, preferably, Ls 1 、Ls 3 and Ls 31 each independently represent -F, -Cl, -CN, -NO 2 、-NCO, -NCS, -OCN, -SCN, -C(O)N(R S0 ) 2 、-C(O)R S0 、a straight-chain or branched alkyl group containing 1 to 10 carbon atoms, a straight-chain or branched alkoxy group containing 1 to 9 carbon atoms, or a straight-chain or branched alkenyl group containing 2 to 10 carbon atoms; more preferably, Ls 1 、Ls 3 and Ls 31 each independently represent -F, -Cl, a straight-chain or branched alkyl group containing 1 to 8 carbon atoms, a straight-chain or branched alkoxy group containing 1 to 7 carbon atoms, or a straight-chain or branched alkenyl group containing 2 to 8 carbon atoms.

[0183] In some embodiments of the present invention, preferably, R S1 represents -Sp 1 -P 1 、a straight-chain or branched alkyl group containing 1 to 10 carbon atoms, a straight-chain or branched alkoxy group containing 1 to 9 carbon atoms, or a straight-chain or branched alkenyl group containing 2 to 10 carbon atoms; more preferably, R S1 represents a straight-chain or branched alkyl group containing 1 to 8 carbon atoms, a straight-chain or branched alkoxy group containing 1 to 7 carbon atoms, or a straight-chain or branched alkenyl group containing 2 to 8 carbon atoms.

[0184] In some embodiments of the present invention, R S2 and R S3 each independently represent -OH, -SH, -NH 2 、-NHR 11 、-N(R 11 ) 2 、-NHC(O)R 11 、-OR 11 、-C(O)OH, or -X 1 。

[0185] In some embodiments of the present invention, R S2 and R S3 are each independently selected from the group consisting of:

[0186] and

[0187] wherein,

[0188] * represents the bonding site in the structure to which it is bonded.

[0189] In some embodiments of the present invention, R S2 and R S3 are each independently selected from the group consisting of:

[0190] and

[0191] Furthermore, R S2 and R S3 are each independently preferably:

[0192] In some embodiments of the present invention, p s1 represents 1 or 2.

[0193] In some embodiments of the present invention, the self - aligning agent of general formula SA accounts for 0.001% to 5% (including any value or sub - range within this range) of the weight of the liquid crystal composition. For example, 0.001%, 0.005%, 0.05%, 0.1%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1.0%, 2%, 3%, 4%, 5%, or the range between any two of these values; preferably, the self - aligning agent of general formula SA accounts for 0.1% to 2% of the weight of the liquid crystal composition.

[0194] In the present invention, when the self - aligning agent of general formula SA is added to the liquid crystal composition, the liquid crystal composition of the present invention can align liquid crystal molecules without setting a PI alignment layer.

[0195] In some embodiments of the present invention, the weight percentage of the chiral agent in the liquid crystal composition is 0.01% - 10% (including any value or sub-range within this range), for example, 0.01%, 0.1%, 0.2%, 0.4%, 0.5%, 0.6%, 0.66%, 0.7%, 0.72%, 0.1%, 1%, 1.1%, 1.14%, 1.2%, 1.25%, 1.3%, 1.36%, 1.5%, 1.8%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.2%, 8.5%, 9%, 9.5%, 10%, or the range between any two of these values; preferably 0.1% - 3%.

[0196] In some embodiments of the present invention, the chiral agent is an S-type chiral compound or an R-type chiral compound.

[0197] In some embodiments of the present invention, the S-type chiral compounds are selected from the group consisting of chiral agents of S1011, S2011, S5011, S811, S6N, and the R-type chiral compounds are selected from the group consisting of chiral agents of R1011, R2011, R5011, R811, R6N.

[0198] In some embodiments of the present invention, the chiral agent is selected from the group consisting of S1011, S2011, and S811.

[0199] In some embodiments of the present invention, the HTP value of the chiral agent ≥ 5 (for example, ≥ 6, ≥ 7, ≥ 7, ≥ 8, ≥ 9, ≥ 10, ≥ 11).

[0200] In addition to the above compounds, the liquid crystal composition of the present invention may also contain conventional nematic liquid crystals, smectic liquid crystals, cholesteric liquid crystals, antioxidants, ultraviolet absorbers, infrared absorbers, photoinitiators, polymerizable monomers, or light stabilizers, etc.

[0201] In some embodiments of the present invention, the liquid crystal composition further contains a dopant, and the dopant is selected from the group consisting of the following compounds:

[0202]

[0203]

[0204] and

[0205]

[0206] In some embodiments of the present invention, the dopant accounts for 0%-5% by weight of the liquid crystal composition, such as 0.3%, 0.5%, 1%, 2%, 3%, 4% or 5%; preferably, the dopant accounts for 0.01%-1% by weight of the liquid crystal composition.

[0207] In addition, antioxidants, light stabilizers and other additives used in the liquid crystal composition of the present invention are preferably the following substances:

[0208]

[0209]

[0210]

[0211]

[0212] Among them, n represents a positive integer from 1 to 12.

[0213] Preferably, the antioxidant is selected from the light stabilizers shown below:

[0214]

[0215] In some embodiments of the present invention, the additives account for 0%-5% by weight of the total weight of the liquid crystal composition, such as 0.3%, 0.5%, 1%, 2%, 3%, 4% or 5%; preferably, the additives account for 0.01%-1% by weight of the total weight of the liquid crystal composition, such as 0.01%, 0.05%, 0.08%, 0.1%, 0.5%, 0.8% or 1%.

[0216] In some embodiments of the present invention, the liquid crystal composition of the present invention further comprises a photoinitiator shown below:

[0217]

[0218] The liquid crystal dimming device of the present invention can be applied in the fields of architecture and transportation.

[0219] Compared with the prior art, the present invention has the following beneficial effects:

[0220] The liquid crystal dimming device of the present invention has appropriate transmittance (T r0 , T r255 ), appropriate contrast, high VHR (initial), high VHR (Ra) and a wide temperature range of use. The dimming device of the present invention has a good display effect when powered on for 2 h and at the moment of power-off, and can effectively avoid the problems of display mura and image retention. Description of the Drawings

[0221] Figure 1 Surface photo of the liquid crystal dimming device of Example 1 when powered on for 2 h at the moment of power-off;

[0222] Figure 2 Surface photo of the liquid crystal dimming device of Comparative Example 1 when powered on for 2 h at the moment of power-off;

[0223] Figure 3 Surface photo of the liquid crystal dimming device of Example 2 when powered on for 2 h at the moment of power-off;

[0224] Figure 4 Surface photo of the liquid crystal dimming device of Comparative Example 2 when powered on for 2 h at the moment of power-off;

[0225] Figure 5 Surface photo of the liquid crystal dimming device of Example 3 when powered on for 2 h at the moment of power-off;

[0226] Figure 6 Surface photo of the liquid crystal dimming device of Comparative Example 3 when powered on for 2 h at the moment of power-off;

[0227] Figure 7 Surface photo of the liquid crystal dimming device of Example 4 when powered on for 2 h at the moment of power-off;

[0228] Figure 8 Surface photo of the liquid crystal dimming device of Comparative Example 4 when powered on for 2 h at the moment of power-off;

[0229] Figure 9 Surface photo of the liquid crystal dimming device of Example 5 when powered on for 2 h at the moment of power-off;

[0230] Figure 10 Surface photo of the liquid crystal dimming device of Comparative Example 5 when powered on for 2 h at the moment of power-off;

[0231] Figure 11 Surface photo of the liquid crystal dimming device of Example 6 when powered on for 2 h at the moment of power-off;

[0232] Figure 12 Surface photo of the liquid crystal dimming device of Comparative Example 6 when powered on for 2 h at the moment of power-off;

[0233] Figure 13 Surface photo of the liquid crystal dimming device of Example 7 when powered on for 2 h at the moment of power-off;

[0234] Figure 14 Surface photo of the liquid crystal dimming device of Comparative Example 7 when powered on for 2 h at the moment of power-off. Detailed implementation mode

[0235] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0236] The present invention will be described below in conjunction with specific implementation schemes. It should be noted that the following embodiments are examples of the present invention, only for illustrating the present invention, and not for limiting the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.

[0237] For the convenience of expression, in the following embodiments, the group structures of each compound are represented by the codes listed in Table 1:

[0238] Table 1. Codes for group structures of compounds

[0239]

[0240] Taking the compound with the following structural formula as an example:

[0241]

[0242] If the structural formula is represented by the codes listed in Table 1, it can be expressed as: nCCGF. The "n" in the code represents the number of C atoms of the alkyl group at the left end. For example, when "n" is "3", it means the alkyl group is -C 3 H 7 ; C in the code represents 1,4-cyclohexylene, G represents 2-fluoro-1,4-phenylene, and F represents fluorine.

[0243] The abbreviated codes for the test items in the following embodiments are as follows:

[0244] Cp Clearing point (transition temperature from nematic phase to isotropic phase, °C)

[0245] Δn Optical anisotropy (589 nm, 25 °C)

[0246] Δε Dielectric anisotropy (1 kHz, 25 °C)

[0247] T c Low-temperature storage phase transition point (i.e., the lower limit temperature of the nematic phase, °C)

[0248] VHR(Initial) Initial voltage holding ratio (%)

[0249] VHR(Ra) Voltage holding ratio after 500 h of high-temperature holding at 85 °C (%)

[0250] t -30℃ Low-temperature storage time (h, -30 °C)

[0251] Tr0 Off-state transmittance (25 °C, %)

[0252] T r255 On-state transmittance (25 °C, %)

[0253] CR contrast ratio (25 °C)

[0254] Wherein,

[0255] Cp: Obtained by testing with a melting point instrument.

[0256] Δn: Δn = n e -n 0 , obtained by testing with an Abbe refractometer under a sodium lamp (589 nm) light source at 25 °C.

[0257] Δε: 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; test conditions: VA type test cell at 25 °C, 1 kHz, and cell thickness of 6 μm.

[0258] T c : Place the nematic liquid crystal material in a glass bottle, store it in a refrigerator at 0 °C, -10 °C, -20 °C, -30 °C, and -40 °C respectively, and then observe the low-temperature situation after 10 days. For example, if the sample is in the nematic phase at -20 °C and becomes a crystal state or a smectic state at -30 °C, then T c is < -20 °C.

[0259] VHR (initial, 25 °C): Initial voltage holding ratio, measured using a TOY06254 type liquid crystal physical property evaluation system; test temperature is 25 °C, test voltage is 5 V, and test frequency is 6 Hz.

[0260] VHR (initial, 60 °C): Initial voltage holding ratio, measured using a TOY06254 type liquid crystal physical property evaluation system; test temperature is 60 °C, test voltage is 5 V, and test frequency is 6 Hz.

[0261] VHR (Ra, 25 °C): Measured using a TOY06254 type liquid crystal physical property evaluation system; the liquid crystal is tested after being held at a high temperature of 85 °C for 500 h, test temperature is 25 °C, test voltage is 5 V, and test frequency is 6 Hz.

[0262] VHR (Ra, 60 °C): Measured using a TOY06254 type liquid crystal physical property evaluation system; the liquid crystal is tested after being held at a high temperature of 85 °C for 500 h, test temperature is 60 °C, test voltage is 5 V, and test frequency is 6 Hz.

[0263] t -30℃ : The time recorded when the nematic liquid crystal medium is placed in a glass bottle, stored at -30°C, and crystals are observed to precipitate.

[0264] CR: The transmittance of the liquid crystal cell is measured using a DMS 505 tester at 255 gray-scale voltages and 0 gray-scale voltage, namely T r255 and T r0 , obtained from T r255 / T r0 .

[0265] In the following examples, each component used can be synthesized by known methods or obtained through commercial channels. These synthesis techniques are conventional, and each liquid crystal compound obtained meets the standards of electronic compounds after testing.

[0266] A liquid crystal composition is prepared according to the ratio of each liquid crystal compound specified in the following examples. The preparation of the liquid crystal composition is carried out according to the conventional methods in the art, such as by heating, ultrasonic, suspension, etc. and mixing in proportion.

[0267] Example 1

[0268] This example provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; wherein, the alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0269] A liquid crystal composition 1 is prepared according to the compounds and their weight percentages listed in Table 2. A dye accounting for 3.8% of the mass of the liquid crystal composition is added to the liquid crystal composition 1, and a chiral agent S811 accounting for 1.14% of the mass of the liquid crystal composition is added to the liquid crystal composition 1, and it is filled in the guest-host liquid crystal composition layer of this example. The performance of the liquid crystal dimming device is tested, and the test results are shown in Table 3.

[0270] Table 2. Formulation of liquid crystal composition

[0271]

[0272]

[0273] Table 3

[0274]

[0275] The liquid crystal dimming device of Example 1 is powered on for 2 h, and the surface of the device at the moment of power-off is as Figure 1 shown.

[0276] Comparative Example 1

[0277] The difference between Comparative Example 1 and Example 1 is only that the orientation directions of the upper alignment layer and the lower alignment layer are anti-parallel. Performance tests were carried out on it, and the results are shown in Table 4.

[0278] Table 4

[0279]

[0280] The liquid crystal dimming device of Comparative Example 1 was powered on for 2 h, and at the moment of power-off, the surface of the device was as Figure 2 shown.

[0281] From the comparison between Comparative Example 1 and Example 1, it can be seen that a liquid crystal composition having a relatively high clearing point, appropriate optical anisotropy, appropriate absolute value of dielectric anisotropy, and good low-temperature storage stability, together with a chiral agent and a dye, are filled in the liquid crystal dimming device of the present invention, so that the liquid crystal dimming device of the present invention has appropriate transmittance (T r0 、T r255 ), appropriate contrast ratio, relatively high VHR (initial), relatively high VHR (Ra), and a relatively wide temperature range of use. From the comparison between Figure 2 and Figure 1 , it can be seen that the dimming device of the present invention has a good display effect at the moment of power-off after being powered on for 2 h, and can effectively avoid the problems of display mura and image retention.

[0282] Example 2

[0283] The present embodiment provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; wherein, the orientation directions of the upper alignment layer and the lower alignment layer are parallel.

[0284] A liquid crystal composition 1 was prepared according to the compounds and their weight percentages listed in Table 2. A dye accounting for 3% of the mass of the liquid crystal composition was added to the liquid crystal composition 1, and a chiral agent S811 accounting for 1.36% of the mass of the liquid crystal composition was added to the liquid crystal composition 1, and it was filled in the guest-host liquid crystal composition layer of the present embodiment. Performance tests were carried out on the liquid crystal dimming device, and the test results are shown in Table 5.

[0285] Table 5

[0286]

[0287] The liquid crystal dimming device of Example 2 was powered on for 2 h, and at the moment of power-off, the surface of the device was as Figure 3 shown.

[0288] Comparative Example 2

[0289] The difference between Comparative Example 2 and Example 2 lies only in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignments.

[0290] Performance tests were carried out on it, and the results are shown in Table 6.

[0291] Table 6

[0292]

[0293] The liquid crystal dimming device of Comparative Example 2 was powered on for 2 h, and at the moment of power-off, the surface of the device was as Figure 4 shown.

[0294] From the comparison between Comparative Example 2 and Example 2, it can be seen that a liquid crystal composition having a relatively high clearing point, appropriate optical anisotropy, appropriate absolute value of dielectric anisotropy, and good low-temperature storage stability, together with a chiral agent and a dye, are filled in the liquid crystal dimming device of the present invention, so that the liquid crystal dimming device of the present invention has appropriate transmittance (T r0 , T r255 ), appropriate contrast ratio, relatively high VHR (initial), relatively high VHR (Ra), and a relatively wide temperature range of use. From the comparison between Figure 4 and Figure 3 , it can be seen that the dimming device of the present invention has a good display effect at the moment of power-off after being powered on for 2 h, and can effectively avoid the problems of display mura and image residue.

[0295] Example 3

[0296] The present embodiment provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; wherein, the alignment directions of the upper alignment layer and the lower alignment layer are parallel alignments.

[0297] A liquid crystal composition 2 was prepared by formulating each compound and its weight percentage listed in Table 7. A dye accounting for 4% of the mass of the liquid crystal composition was added to the liquid crystal composition 2, and a chiral agent S811 accounting for 1.1% of the mass of the liquid crystal composition was added to the liquid crystal composition 2, and it was filled in the guest-host liquid crystal composition layer of the present embodiment. Performance tests were carried out on the liquid crystal dimming device, and the test results are shown in Table 8.

[0298] Table 7. Formulation of liquid crystal composition

[0299]

[0300]

[0301] Table 8

[0302]

[0303] The liquid crystal dimming device of Example 3 was powered on for 2 h, and at the moment of power-off, the surface of the device was as Figure 5 shown.

[0304] Comparative Example 3

[0305] The difference between this Comparative Example 3 and Example 3 is only that the orientation directions of the upper alignment layer and the lower alignment layer are anti-parallel.

[0306] Its performance was tested, and the results are shown in Table 9.

[0307] Table 9

[0308]

[0309] The liquid crystal dimming device of Comparative Example 3 was powered on for 2 h, and at the moment of power-off, the surface of the device was as Figure 6 shown.

[0310] From the comparison between Comparative Example 3 and Example 3, it can be seen that a liquid crystal composition having a relatively high clearing point, appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy, and good low-temperature storage stability, together with a chiral agent and a dye, are filled in the liquid crystal dimming device of the present invention, so that the liquid crystal dimming device of the present invention has an appropriate transmittance (T r0 , T r255 ), appropriate contrast, a relatively high VHR (initial), a relatively high VHR (Ra), and a relatively wide temperature range of use. From the comparison between Figure 6 and Figure 5 , it can be seen that the dimming device of the present invention has a good display effect at the moment of power-off after being powered on for 2 h, and can effectively avoid the problems of display mura and image retention.

[0311] Example 4

[0312] This example provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; wherein, the orientation directions of the upper alignment layer and the lower alignment layer are parallel.

[0313] A liquid crystal composition 2 was prepared according to the compounds and their weight percentages listed in Table 7. A dye accounting for 3.6% of the mass of the liquid crystal composition was added to the liquid crystal composition 2, and a chiral agent S1011 accounting for 0.72% of the mass of the liquid crystal composition was added to the liquid crystal composition 2, and it was filled in the guest-host liquid crystal composition layer of this example. The performance of the liquid crystal dimming device was tested, and the test results are shown in Table 10.

[0314] Table 10

[0315]

[0316]

[0317] The liquid crystal dimming device of Example 4 was powered on for 2 h, and at the moment of power-off, the surface of the device was as Figure 7 shown.

[0318] Comparative Example 4

[0319] The difference between this Comparative Example 4 and Example 4 is only that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel.

[0320] Its performance was tested, and the results are shown in Table 11.

[0321] Table 11

[0322]

[0323] The liquid crystal dimming device of Comparative Example 4 was powered on for 2 h, and at the moment of power-off, the surface of the device was as Figure 8 shown.

[0324] From the comparison between Comparative Example 4 and Example 4, it can be seen that a liquid crystal composition having a relatively high clearing point, appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy, and good low-temperature storage stability, together with a chiral agent and a dye, are filled in the liquid crystal dimming device of the present invention, so that the liquid crystal dimming device of the present invention has appropriate transmittance (T r0 , T r255 ), appropriate contrast ratio, a relatively high VHR (initial), a relatively high VHR (Ra), and a relatively wide temperature range of use. From the Figure 8 and Figure 7 comparison, it can be seen that the dimming device of the present invention has a good display effect at the moment of power-off after being powered on for 2 h, and can effectively avoid the problems of display mura and image residue.

[0325] Example 5

[0326] This example provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; wherein, the alignment directions of the upper alignment layer and the lower alignment layer are parallel.

[0327] A liquid crystal composition 3 was prepared by formulating the compounds listed in Table 12 and their weight percentages. A dye accounting for 3% of the mass percentage of the liquid crystal composition was added to the liquid crystal composition 3, and a chiral agent S811 accounting for 1.3% of the mass percentage of the liquid crystal composition was added to the liquid crystal composition 3, and it was filled in the guest-host liquid crystal composition layer of this example. The liquid crystal dimming device was tested for performance, and the test results are shown in Table 13.

[0328] Table 12. Formulation of liquid crystal composition

[0329]

[0330]

[0331] Table 13

[0332]

[0333] The liquid crystal dimming device of Example 5 was powered on for 2 h, and at the moment of power-off, the surface of the device was as Figure 9 shown.

[0334] Comparative Example 5

[0335] The difference between this Comparative Example 5 and Example 5 is only that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignments.

[0336] Its performance was tested, and the results are shown in Table 14.

[0337] Table 14

[0338]

[0339] The liquid crystal dimming device of Comparative Example 5 was powered on for 2 h, and at the moment of power-off, the surface of the device was as Figure 10 shown.

[0340] From the comparison between Comparative Example 5 and Example 5, it can be seen that a liquid crystal composition having a relatively high clearing point, appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy, and good low-temperature storage stability, together with a chiral agent and a dye, are filled in the liquid crystal dimming device of the present invention, so that the liquid crystal dimming device of the present invention has appropriate transmittance (T r0 , T r255 ), appropriate contrast ratio, relatively high VHR (initial), relatively high VHR (Ra), and a relatively wide temperature range of use. From the comparison between Figure 10 and Figure 9 , it can be seen that the dimming device of the present invention has a good display effect at the moment of power-off after being powered on for 2 h, and can effectively avoid the problems of display mura and image retention.

[0341] Example 6

[0342] This example provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; wherein, the alignment directions of the upper alignment layer and the lower alignment layer are parallel alignments.

[0343] Prepare a liquid crystal composition 3 according to the compounds listed in Table 12 and their weight percentages. Add a dye accounting for 3.8% of the mass percentage of the liquid crystal composition to the liquid crystal composition 3, add a chiral agent S1011 accounting for 1.25% of the mass percentage of the liquid crystal composition to the liquid crystal composition 3, and fill it into the guest-host liquid crystal composition layer of this example. Perform performance tests on the liquid crystal dimming device, and the test results are shown in Table 15.

[0344] Table 15

[0345]

[0346]

[0347] Power on the liquid crystal dimming device of Example 6 for 2 h. At the moment of power-off, the surface of the device is as Figure 11 shown.

[0348] Comparative Example 6

[0349] The difference between this Comparative Example 6 and Example 6 is only that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignments.

[0350] Perform performance tests on it, and the results are shown in Table 16.

[0351] Table 16

[0352]

[0353] Power on the liquid crystal dimming device of Comparative Example 6 for 2 h. At the moment of power-off, the surface of the device is as Figure 12 shown.

[0354] From the comparison between Comparative Example 6 and Example 6, it can be seen that filling a liquid crystal composition with a relatively high clearing point, appropriate optical anisotropy, appropriate absolute value of dielectric anisotropy, and good low-temperature storage stability, together with a chiral agent and a dye, into the liquid crystal dimming device of the present invention enables the liquid crystal dimming device of the present invention to have appropriate transmittance (T r0 , T r255 ), appropriate contrast ratio, relatively high VHR (initial), relatively high VHR (Ra), and a relatively wide temperature usage range. From the comparison between Figure 12 and Figure 11 , it can be seen that the dimming device of the present invention has a good display effect at the moment of power-off after being powered on for 2 h, and can effectively avoid the problems of display mura and image residue.

[0355] Example 7

[0356] This embodiment provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; wherein, the alignment directions of the upper alignment layer and the lower alignment layer are parallel alignments.

[0357] Prepare a liquid crystal composition 3 according to the compounds and their weight percentages listed in Table 12, add a dye accounting for 3.8% of the mass percentage of the liquid crystal composition to the liquid crystal composition 3, add a chiral agent S2011 accounting for 0.66% of the mass percentage of the liquid crystal composition to the liquid crystal composition 3, and fill it in the guest-host liquid crystal composition layer of this embodiment. Perform performance tests on the liquid crystal dimming device, and the test results are shown in Table 17.

[0358] Table 17

[0359]

[0360] Power on the liquid crystal dimming device of Example 7 for 2 h, and at the moment of power-off, the surface of the device is as Figure 13 shown.

[0361] Comparative Example 7

[0362] The difference between this Comparative Example 6 and Example 6 is only that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignments.

[0363] Perform performance tests on it, and the results are shown in Table 18.

[0364] Table 18

[0365]

[0366] Power on the liquid crystal dimming device of Comparative Example 7 for 2 h, and at the moment of power-off, the surface of the device is as Figure 14 shown.

[0367] From the comparison between Comparative Example 7 and Example 7, it can be seen that filling a liquid crystal composition with a relatively high clearing point, appropriate optical anisotropy, appropriate absolute value of dielectric anisotropy, and good low-temperature storage stability, together with a chiral agent and a dye, into the liquid crystal dimming device of the present invention enables the liquid crystal dimming device of the present invention to have appropriate transmittance (T r0 , T r255 ), appropriate contrast ratio, relatively high VHR (initial), relatively high VHR (Ra), and a relatively wide temperature usage range. From the comparison between Figure 14 and Figure 13 , it can be seen that the dimming device of the present invention has a good display effect at the moment of power-off after being powered on for 2 h, and can effectively avoid the problems of display mura and image residue.

[0368] Example 8

[0369] This embodiment provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; wherein, the alignment directions of the upper alignment layer and the lower alignment layer are parallel alignments.

[0370] A liquid crystal composition 4 was formulated according to the compounds and their weight percentages listed in Table 19. A dye accounting for 3.8% of the mass percentage of the liquid crystal composition was added to the liquid crystal composition 4, and a chiral agent S811 accounting for 1.14% of the mass percentage of the liquid crystal composition was added to the liquid crystal composition 4, and it was filled in the guest-host liquid crystal composition layer of this embodiment. The performance of the liquid crystal dimming device was tested, and the test results are shown in Table 20.

[0371] Table 19. Formulation of Liquid Crystal Composition

[0372]

[0373] Table 20

[0374]

[0375]

[0376] Comparative Example 8

[0377] The difference between this Comparative Example 8 and Embodiment 8 is only that the alignment directions of the upper alignment layer and the lower alignment layer are antiparallel alignments. Its performance was tested, and the results are shown in Table 21.

[0378] Table 21

[0379]

[0380] From the comparison between Comparative Example 8 and Embodiment 8, it can be seen that a liquid crystal composition having a relatively high clearing point, appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy, and good low-temperature storage stability, together with a chiral agent and a dye, are filled in the liquid crystal dimming device of the present invention, so that the liquid crystal dimming device of the present invention has appropriate transmittance (T r0 , T r255 ), appropriate contrast, a relatively high VHR (initial), a relatively high VHR (Ra), and a relatively wide temperature usage range, and can effectively avoid the problems of display mura and image residue.

[0381] Embodiment 9

[0382] This embodiment provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; wherein, the alignment directions of the upper alignment layer and the lower alignment layer are parallel alignments.

[0383] Prepare a liquid crystal composition 4 according to the compounds listed in Table 22 and their weight percentages. Add a dye accounting for 4% of the mass percentage of the liquid crystal composition to the liquid crystal composition 4, add a chiral agent S811 accounting for 1.1% of the mass percentage of the liquid crystal composition to the liquid crystal composition 4, and fill it into the guest-host liquid crystal composition layer of this example. Perform performance tests on the liquid crystal dimming device, and the test results are shown in Table 23.

[0384] Table 22. Formulation of liquid crystal composition

[0385]

[0386] Table 23

[0387]

[0388]

[0389] Comparative Example 9

[0390] The difference between this Comparative Example 9 and Example 9 is only that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignments.

[0391] Perform performance tests on it, and the results are shown in Table 24.

[0392] Table 24

[0393]

[0394] From the comparison between Comparative Example 9 and Example 9, it can be seen that a liquid crystal composition with a relatively high clearing point, appropriate optical anisotropy, appropriate absolute value of dielectric anisotropy, and good low-temperature storage stability, together with a chiral agent and a dye, are filled into the liquid crystal dimming device of the present invention, enabling the liquid crystal dimming device of the present invention to have appropriate transmittance (T r0 , T r255 ), appropriate contrast ratio, relatively high VHR (initial), relatively high VHR (Ra), and a relatively wide temperature range of use.

[0395] Example 10

[0396] This example provides a liquid crystal dimming device, which sequentially includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate from bottom to top; wherein, the alignment directions of the upper alignment layer and the lower alignment layer are parallel alignments.

[0397] A liquid crystal composition 4 was prepared according to the compounds and their weight percentages listed in Table 7. A dye accounting for 3.6% of the mass percentage of the liquid crystal composition was added to the liquid crystal composition 4, and a chiral agent S1011 accounting for 0.72% of the mass percentage of the liquid crystal composition was added to the liquid crystal composition 4, and it was filled in the guest-host liquid crystal composition layer of this example. The performance of the liquid crystal dimming device was tested, and the test results are shown in Table 25.

[0398] Table 25

[0399]

[0400] Comparative Example 10

[0401] The difference between this Comparative Example 10 and Example 10 is only that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignments.

[0402] Its performance was tested, and the results are shown in Table 26.

[0403] Table 26

[0404]

[0405]

[0406] From the comparison between Comparative Example 10 and Example 10, it can be seen that a liquid crystal composition with a relatively high clearing point, appropriate optical anisotropy, appropriate absolute value of dielectric anisotropy, and good low-temperature storage stability, together with a chiral agent and a dye, are filled in the liquid crystal dimming device of the present invention, making the liquid crystal dimming device of the present invention have appropriate transmittances (T r0 、T r255 ), appropriate contrast ratio, relatively high VHR (initial), relatively high VHR (Ra), and a relatively wide temperature usage range.

[0407] In summary, the liquid crystal dimming device of the present invention has appropriate transmittances (T r0 is 12.6 - 21.4, T r255 is 53.4 - 64.2), appropriate contrast ratio (3 - 4.5), relatively high VHR (initial) (VHR (initial, 25 °C) is above 84, VHR (initial, 60 °C) is above 55), relatively high VHR (Ra) (VHR (Ra, 25 °C) is above 62, VHR (Ra, 60 °C) is above 14, and even up to above 23), and a relatively wide temperature usage range (low-temperature storage phase transition point ≥ -30 °C). The dimming device of the present invention has a good display effect when powered on for 2 h and at the moment of power-off, and can effectively avoid the problems of display mura and image retention.

[0408] The applicant declares that the present invention uses the above embodiments to illustrate the liquid crystal dimming device of the present invention, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of the raw materials selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A liquid crystal dimming device, characterized in that, the liquid crystal dimming device successively includes a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer and an upper substrate from bottom to top; the alignment directions of the upper alignment layer and the lower alignment layer are parallel alignments; the guest-host liquid crystal composition layer contains at least one dichroic dye, at least one chiral agent and at least one liquid crystal composition; wherein, the liquid crystal composition contains at least one liquid crystal compound of general formula N and at least one compound of general formula M, and the liquid crystal compound of general formula N is: wherein, R N1 and R N2 each independently represents a straight-chain or branched alkyl group having 1 to 12 carbon atoms, one or two or more non-adjacent -CH in a straight-chain or branched alkyl group having 1 to 12 carbon atoms 2 - may be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-; Ring and the ring each independently represents wherein one or more of the -CH 2 - in may be replaced by -O-, and the single bond in one or more of the rings may be replaced by a double bond, wherein one or more of the -H in may be independently replaced by -F, -Cl or -CN respectively, and -CH= in one or more of the rings may be replaced by -N=; Z N1 and Z N2 each independently represents a single bond, -CO-O-, -O-CO-, -CH 2 O-, -OCH 2 -, -CH=CH-, -C≡C-, -CH 2 CH 2 -, -CF 2 CF 2 -, -(CH 2 ) 4 -, -CF 2 O- or -OCF 2 -; L N1 and L N2 each independently represents -H, a halogen, an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms; and n N1 represents 0, 1, 2, or 3, and n N2 represents 0 or 1, and 0 ≤ n N1 + n N2 ≤ 3, when n N1 = 2 or 3, the rings can be the same or different, and Z N1 can be the same or different; the compound of general formula M is: wherein, R M1 and R M2 each independently represents a straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms, one or two or more non-adjacent -CH in a straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms 2 - may be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-; Ring Ring and Ring each independently represents wherein one or more of the -CH 2 - in may be replaced by -O-, and one or more single bonds in the ring may be replaced by double bonds, and at most one -H in may be substituted by a halogen; Z M1 and Z M2 each independently represents a single bond, -CO-O-, -O-CO-, -CH 2 O-, -OCH 2 -, -C≡C-, -CH=CH-, -CH 2 CH 2 -, or -(CH 2 ) 4 -; and n M represents 0, 1, or 2, where when n M = 2, the rings may be the same or different, and Z M2 may be the same or different; the dielectric anisotropy of the liquid crystal composition < 0; the VHR(Ra, 25 °C) of the liquid crystal dimming device is 62 or more.

2. The liquid crystal dimming device according to claim 1, characterized in that, the liquid crystal compound of general formula N is: wherein, R N1 and R N2 each independently represents a straight-chain or branched alkyl group having 1 to 12 carbon atoms, and one or more than two non-adjacent -CH 2 - in the straight-chain or branched alkyl group having 1 to 12 carbon atoms may be independently replaced by -CH=CH- or -O-; Ring and the ring each independently represents wherein one or more of the -CH 2 - may be replaced by -O-, and single bonds in one or more of the rings may be replaced by double bonds, wherein one or more of the -H may be independently replaced by -F; Z N1 and Z N2 each independently represents a single bond, -CH 2 O-, -OCH 2 -, -CH=CH- or -CH 2 CH 2 -; L N1 and L N2 each independently represents -H; and n N1 represents 0, 1, 2, or 3, where n N2 represents 0 or 1, and 0 ≤ n N1 + n N2 ≤ 3, when n N1 = 2 or 3, the rings can be the same or different, Z N1 can be the same or different.

3. The liquid crystal dimming device according to claim 1, characterized in that, the liquid crystal compound of general formula N is: wherein, R N1 and R N2 each independently represents a straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms, and one or two or more non-adjacent -CH 2 - in the straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms may be independently replaced by -CH=CH- or -O-; Ring and the ring each independently represents wherein one or more of the -H therein may each independently be replaced by -F; Z N1 and Z N2 each independently represents a single bond; L N1 and L N2 each independently represents -H; and n N1 represents 0, 1, or 2, where n N2 represents 0 or 1, and 0 ≤ n N1 + n N2 ≤ 3, when n N1 = 2, the rings can be the same or different, Z N1 can be the same or different.

4. The liquid crystal dimming device according to claim 1, characterized in that, the liquid crystal compound of general formula N is selected from the group consisting of the following compounds: and 5. The liquid crystal dimming device according to claim 4, characterized in that, the compound of general formula N is selected from the group consisting of the compound of general formula N-2, the compound of general formula N-5, and the compound of general formula N-11.

6. The liquid crystal dimming device according to claim 1, characterized in that, the dichroic dye is selected from one or more dyes in the group consisting of azo, anthraquinone, phthalocyanine, cyanine, indigo, arylmethane, nitro and nitroso.

7. The liquid crystal dimming device according to claim 6, characterized in that, the dichroic dye is selected from the group consisting of the following compounds: and 8. The liquid crystal dimming device according to claim 1, characterized in that, the weight percentage of the dichroic dye in the liquid crystal composition is 0.01% - 10%.

9. The liquid crystal dimming device according to claim 1, characterized in that, the chiral agent is an S-type chiral compound or an R-type chiral compound.

10. The liquid crystal dimming device according to claim 9, characterized in that, the S-type chiral compound is selected from the group consisting of chiral agents S1011, S2011, S5011, S811, and the R-type chiral compound is selected from the group consisting of chiral agents R1011, R2011, R5011, R811:

11. The liquid crystal dimming device according to claim 1, characterized in that, the compound of general formula M is: wherein, R M1 and R M2 each independently represents a straight-chain or branched alkyl group having 1 to 12 carbon atoms, one or more non-adjacent -CH in a straight-chain or branched alkyl group having 1 to 12 carbon atoms 2 - may be independently replaced by -CH=CH- or -O-; Ring Ring and Ring each independently represents wherein one or more of the -CH 2 - can be replaced by -O-, and in one or more rings, a single bond can be replaced by a double bond, at most one -H in can be substituted by a halogen; Z M1 and Z M2 each independently represents a single bond, -CO-O-, -O-CO-, -CH 2 O-, -OCH 2 -, or -CH=CH-; and n M represents 0, 1, or 2, where when n M = 2, the rings may be the same or different, and Z M2 may be the same or different.

12. The liquid crystal dimming device according to claim 11, characterized in that, the compound of general formula M is: wherein, R M1 and R M2 each independently represents a straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms, one or more than two non-adjacent -CH 2 - in the straight-chain or branched-chain alkyl group having 1 to 12 carbon atoms may be independently replaced by -CH=CH- or -O-; Ring Ring and the ring each independently represents wherein at most one -H in may be substituted by a halogen; Z M1 and Z M2 each independently represents a single bond, -CO-O-, -O-CO-, -CH 2 O-, or -OCH 2 -; and n M represents 0, 1, or 2, where when n M = 2, the rings may be the same or different, and Z M2 may be the same or different.

13. The liquid crystal dimming device according to claim 1, characterized in that, the compound of general formula M is selected from the group consisting of the following compounds: and 14. The liquid crystal dimming device according to claim 13, characterized in that, The compound of general formula M is selected from the group consisting of compounds of general formula M-1, compounds of general formula M-2, compounds of general formula M-12, compounds of general formula M-16, compounds of general formula M-26, compounds of general formula M-27, compounds of general formula M-28, compounds of general formula M-29, compounds of general formula M-30, compounds of general formula M-31, compounds of general formula M-32, and compounds of general formula M-33.

15. The liquid crystal dimming device according to claim 13, characterized in that the compound of general formula M comprises at least one compound selected from the group consisting of compounds of general formula M-26, compounds of general formula M-27, compounds of general formula M-28, compounds of general formula M-29, compounds of general formula M-30, compounds of general formula M-31, compounds of general formula M-32, and compounds of general formula M-33.

16. The liquid crystal dimming device according to claim 1, characterized in that the weight percentage of the compound of general formula N in the liquid crystal composition is 0.1%-98%, and the weight percentage of the compound of general formula M in the liquid crystal composition is 0.1%-60%.

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