CN111117654A

CN111117654A - Liquid crystal composition and display device thereof

Info

Publication number: CN111117654A
Application number: CN201811272240.1A
Authority: CN
Inventors: 徐海彬; 贺笛; 姚利芳; 张文琦
Original assignee: Jiangsu Hecheng Display Technology Co Ltd
Current assignee: Jiangsu Hecheng Display Technology Co Ltd
Priority date: 2018-10-30
Filing date: 2018-10-30
Publication date: 2020-05-08
Anticipated expiration: 2038-10-30
Also published as: TW202016268A; KR20200050362A; KR102236275B1; CN111117654B; TWI762826B

Abstract

The invention discloses a liquid crystal composition, which comprises the following components in part by weight: one or more compounds of formula (I); one or more compounds of formula M; and one or more compounds of formula A-1. The invention also discloses a liquid crystal display device comprising the liquid crystal composition. The liquid crystal composition of the present invention has a large vertical dielectric constant epsilon while maintaining the clearing point, optical anisotropy, dielectric anisotropy and low-temperature storage stability at normal levels_⊥A large vertical dielectric to dielectric ratio epsilon_⊥A large average elastic constant K_aveSmaller rotational viscosity gamma 1, larger VHR (initial) and VHR (UV) and VHR (high temperature) (i.e. better reliability), and higher transmittance, so that the liquid crystal display device comprising the liquid crystal composition of the present invention has higher transmittance, higher contrast ratio, and faster response speed, which is particularly suitable for driving active matrix thin film transistorsThe liquid crystal display element of (1).

Description

Liquid crystal composition and display device thereof

Technical Field

The invention relates to the field of liquid crystal materials, in particular to a liquid crystal composition and a display device thereof.

Background

Liquid crystal display elements are used in various household appliances such as watches and calculators, measuring instruments, automobile panels, word processors, computers, printers, televisions, and the like. The display mode is classified into PC (phase change), TN (twisted nematic), STN (super twisted nematic), ECB (electrically controlled birefringence), OCB (optically compensated bend), IPS (in-plane switching), VA (vertical alignment), and the like, according to the type of the display mode. The driving method of the element is classified into a PM (passive matrix) type and an AM (active matrix) type. PM is classified into static (static) and multiplex (multiplex) types. AM is classified into a TFT (thin film transistor), an MIM (metal insulator metal), and the like. The types of TFTs are amorphous silicon (amorphous silicon) and polycrystalline silicon (polysilicon). The latter is classified into a high temperature type and a low temperature type according to a manufacturing process. Liquid crystal display elements are classified into a reflection type using natural light, a transmission type using backlight, and a semi-transmission type using both light sources of natural light and backlight, depending on the type of light source.

In low information content, passive driving is generally used, but as the information content increases, the display size and the number of display paths increase, and the crosstalk and contrast reduction phenomenon become serious, so that Active Matrix (AM) driving is generally used, and Thin Film Transistors (TFTs) are often used for driving at present. In an AM-TFT element, the TFT switching devices are addressed in a two-dimensional grid, charge up the pixel electrodes for a finite time on, and then turn off until they are addressed again in the next cycle. Therefore, between two addressing periods, it is not desirable to change the voltage on the pixel, otherwise the transmittance of the pixel will change, resulting in unstable display. The rate of discharge at a pixel depends on the electrode capacity and the resistivity of the dielectric material between the electrodes. Therefore, the liquid crystal material is required to have higher resistivity, appropriate optical anisotropy Δ n (the Δ n value is generally about 0.08-0.13) and lower threshold voltage, so as to achieve the purposes of reducing driving voltage and reducing power consumption; it is also required to have a low viscosity to meet the demand for a rapid response. Such liquid crystal compositions have been reported in many documents, for example, WO9202597, WO9116398, WO9302153, WO9116399, CN1157005A and the like.

In the early 70 s of the last century, researchers have conducted experimental studies on the basic electro-optical characteristics of the uniformly aligned and twisted nematic liquid crystal IPS mode, which is characterized by a pair of electrodes fabricated on the same substrate, but without electrodes on the other substrate, and by the lateral electric field applied between the electrodes to control the alignment of the liquid crystal molecules, and thus this mode can also be referred to as the lateral field mode. In the IPS mode, nematic liquid crystal molecules are uniformly arranged in parallel between two substrates, and two polarizing plates are orthogonally arranged. In the IPS mode, when no electric field is applied, incident light is blocked by two orthogonal polarizing plates to be in a dark state, and when an electric field is applied, liquid crystal molecules rotate to cause retardation, so that light leaks from the two orthogonal polarizing plates.

Since IPS mode devices are simple to fabricate and have a wide viewing angle, they become the most attractive solution capable of improving viewing angle characteristics and realizing large-area display.

The display device of the IPS mode may use either positive liquid crystal or negative liquid crystal, because the transmittance saturation voltage (i.e., the driving voltage at which the transmittance is at a maximum value) decreases with an increase in the absolute value of Δ ε, and thus the transmittance saturation voltage of the positive liquid crystal is lower than that of the negative liquid crystal and the response speed is faster, but the negative liquid crystal is better than that of the positive liquid crystal, mainly due to the difference in rotation of the positive and negative liquid crystals under an electric field_⊥The transmittance of the liquid crystal display can be greatly improved on the premise of keeping low driving voltage by doping the negative liquid crystal in the positive IPS liquid crystal. Although there has been in the prior art the addition of negative liquid crystal monomers to positive liquid crystal compositionsHowever, the negative liquid crystal monomer doped in the liquid crystal composition causes a decrease in dielectric constant of the liquid crystal composition, and also causes deterioration in reliability and a slow response speed of the liquid crystal display.

In addition, studies have shown that the most significant factor affecting the contrast ratio of a liquid crystal display element is light leakage of the liquid crystal material, while the major factor affecting light leakage is light Scattering (LC Scattering), which is associated with the average elastic constant K_aveThe relationship of (A) is as follows:

wherein d represents the cell gap, n_eDenotes the extraordinary refractive index, and n_oIndicating the ordinary refractive index. According to the relation, LC Scattering and K_aveIn inverse proportion, in increasing K_aveIn the case of (2), light leakage of the liquid crystal material can be reduced.

Further, the Contrast (CR) and the luminance (L) are related as follows:

CR＝L₂₅₅/L₀×100％，

wherein L is₂₅₅Is at on-state brightness, L₀Is off state brightness. It can be seen that what significantly affects CR should be L₀A change in (c). In the off state, L₀The smaller the LC Scattering, L, is, regardless of the dielectric of the liquid crystal molecules, and of the liquid crystal material itself₀The smaller the CR, the more significant the CR will be.

A liquid crystal display element containing a liquid crystal composition having a large absolute value of dielectric anisotropy can reduce the base voltage value, reduce the driving voltage, and further reduce the power consumption.

The liquid crystal display element containing the liquid crystal composition with the lower threshold voltage can effectively reduce the power consumption of display, and has longer endurance time particularly in consumables, such as portable electronic products like mobile phones, tablet computers and the like. However, for liquid crystal compositions having a lower threshold voltage (generally containing large dielectric polar groups), the degree of order of the liquid crystal molecules is low, and converselyK of degree of order of enantiomorphic liquid crystal molecules_aveThe value also decreases, affecting the light leakage and contrast of the liquid crystal material, which are generally difficult to achieve simultaneously.

The liquid crystal composition with low viscosity can improve the response speed of the liquid crystal display element. When the response speed of the liquid crystal display element is high, it can be applied to animation display. In addition, when the liquid crystal composition is injected into the cell of the liquid crystal display device, the injection time can be shortened, and the workability can be improved.

The prior art discloses a liquid crystal composition with lower power consumption and faster response speed, such as patent document CN102858918A, but the liquid crystal composition in the prior art has the problems of environmental protection (such as use of chlorine-containing compounds), short service life (such as poor stability to UV or heat), low contrast (such as whitening of a display screen under sunlight), and incapability of simultaneously satisfying the performance balance of proper optical anisotropy, proper dielectric anisotropy, high voltage holding ratio, good UV resistance stability and high temperature stability in liquid crystal televisions, tablet computers, and the like, and cannot simultaneously satisfy all indexes.

From the preparation angle of the liquid crystal material, various performances of the liquid crystal material are mutually influenced by the influence, and other performances may be changed by improving a certain performance index. Therefore, creative efforts are often required to prepare liquid crystal materials having suitable properties in all aspects.

The liquid crystal material is an important component of the liquid crystal display, and the liquid crystal display has great market demand at present, is mostly used in electronic and electric products, but has a short life cycle. The problem of waste pollution naturally exists in a short life cycle, and under the condition that the current green environmental protection problem is increasingly emphasized by various social circles, if the problem can be controlled from a source, namely, an environment-friendly green material is selected in the modulation process of the liquid crystal material, the environmental cost for treating the waste liquid crystal display can be greatly reduced. Therefore, creative labor is often required to prepare the liquid crystal material with proper performance in all aspects and economic, green and environment-friendly properties.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the defects of the prior artThe present invention has an object to provide a high perpendicular dielectric constant epsilon while maintaining the clearing point, optical anisotropy, dielectric anisotropy and low temperature storage stability at normal levels_⊥A large vertical dielectric to dielectric ratio epsilon_⊥A large average elastic constant K_aveSmaller rotational viscosity γ 1, larger VHR (initial) and VHR (uv) and VHR (high temperature) (i.e. better reliability), and higher transmittance, enable a liquid crystal display device comprising the same to have higher transmittance, higher contrast, and faster response speed, and are particularly suitable for liquid crystal compositions in liquid crystal display elements driven by active matrix thin film transistors (AM-TFTs). It is also an object of the present invention to provide a display device comprising the liquid crystal composition.

The technical scheme of the invention is as follows:

in order to achieve the above object, the present invention provides a liquid crystal composition comprising:

one or more compounds of formula (I)

One or more compounds of the formula M

One or more compounds of formula A-1

Wherein,

R₁and R_A1Each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms,

1 or non-adjacent 2 or more-CH in the linear or branched alkyl containing 1 to 12 carbon atoms₂-said linear or branched alkyl radical containing from 1 to 12 carbon atoms which may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-or-O-CO-, respectively,

Each of one or more-H may be independently substituted with-F or-Cl;

R_M1and R_M2Each independently represents-H, a linear or branched alkyl group having 1 to 12 carbon atoms,

1 or non-adjacent 2 or more-CH in the linear or branched alkyl containing 1 to 12 carbon atoms₂-may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-;

Z₁、Z₂and Z₃Each independently represents a single bond, -CH₂CH₂-、-CF₂CF₂-、-CO-O-、-O-CO-、-O-CO-O-、-CH＝CH-、-CF＝CF-、-CH₂O-or-OCH₂-；

Z_A11Represents a single bond, -CH₂CH₂-、-CF₂CF₂-、-CO-O-、-O-CO-、-O-CO-O-、-CH＝CH-、-CF＝CF-、-CH₂O-or-OCH₂-；

Z_M1And Z_M2Each independently represents a single bond, -CO-O-, -O-CO-, -CH₂O-、-OCH₂-、-CH＝CH-、-C≡C-、-CH₂CH₂-or- (CH)₂)₄-；

L₁、L₂、L₃、L₄、L_A11、L_A12And L_A13Each independently represents-H, contains 1-3Alkyl of carbon atoms or halogen;

x and X_A1Each independently represents halogen, haloalkyl or haloalkoxy having 1 to 5 carbon atoms, haloalkenyl or haloalkenyloxy having 2 to 5 carbon atoms;

ring (C)

And ring

Each independently represent

Wherein,

one or more-CH₂-may be replaced by-O-, one or more of the ring single bonds may be replaced by double bonds,

may be substituted by-CN, -F or-Cl, and one or more rings may be substituted by-CH ═ by-N;

ring (C)

Ring (C)

And ring

Each independently represent

Wherein,

one or more-CH of₂-can be replaced by-O-,

at most one-H in (a) may be substituted by halogen;

ring (C)

And ring

Each independently represent

Wherein,

n1 and n2 each independently represent 0, 1 or 2, and 0. ltoreq. n1+ n 2. ltoreq.3, and when n 1. ltoreq.2, the ring

May be the same or different, Z₁Which may be the same or different, when n2 is 2, the ring

May be the same or different, Z₂May be the same or different;

n_M1and n_A11Each independently represents 0, 1, 2 or 3, and when n_M1When 2 or 3, ring

May be the same or different, Z_M2May be the same or different, when n_A11When 2 or 3, ring

May be the same or different, Z_A11May be the same or different; and is

n_A12Represents 1 or 2, and when n_A12When 2, ring

May be the same or different.

In some embodiments of the present invention, the content of the compound of formula i is desirably adjusted according to the required properties of solubility at low temperature, transition temperature, electrical reliability, transmittance, contrast, birefringence, process adaptability, dropping marks, burn-in, dielectric anisotropy, and the like.

The compounds of the general formula I preferably represent the liquid crystal compositions according to the invention in a weight ratio: the lower limit of the weight percentage of the compound of formula i in the liquid crystal composition of the present invention is preferably 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 20%, 30% or 40% relative to the total weight of the liquid crystal composition of the present invention; the upper limit of the weight percentage of the compound of formula I in the liquid crystal composition of the present invention is preferably 60%, 55%, 50%, 45%, 40%, 35%, 30%, 28%, 27%, 26%, 25.5%, 25%, 24.5%, 24%, 22%, 20%, 18%, 16% or 15% relative to the total weight of the liquid crystal composition of the present invention.

In some embodiments of the invention, the compound of formula I is present in an amount of 0.1% to 60% by weight of the liquid crystal composition.

In some embodiments of the invention, in the compounds of formula i, when n1 ═ 0 and n2 ═ 1, Z is₂And Z₃At least one of which is not a single bond; when n1 is 1 and n2 is 0, Z is₁And Z₃At least one ofIs a single bond.

In some embodiments of the invention, in the compounds of formula I, R₁Preferably a linear or branched alkyl or alkoxy group having 1 to 8 carbon atoms, a linear or branched alkenyl or alkenyloxy group having 2 to 8 carbon atoms; further preferred is a linear or branched alkyl group or alkoxy group having 1 to 5 carbon atoms, a linear or branched alkenyl group or alkenyloxy group having 2 to 5 carbon atoms.

In some embodiments of the invention, the ring

And ring

Each independently represent

In some embodiments of the invention, L₁、L₂、L₃And L₄Each independently represents-H, -CH₃-F or-Cl.

In some embodiments of the invention, the compound of formula i is selected from the group consisting of:

wherein,

L₁、L₂and L₅Each independently represents-H or-F; and is

R_xAnd R_yEach independently represents-CH₂-or-O-.

In some embodiments of the present invention, preferably, in the compounds of formula I-1 to formula I-8, L₅represents-H.

In some embodiments of the present invention, the compound of formula I is preferably selected from the group consisting of compounds of formula I-1, formula I-2, formula I-3, formula I-4, formula I-5, formula I-6, formula I-7, and formula I-8.

In some embodiments of the present invention, the liquid crystal composition of the present invention preferably comprises at least two compounds of formula I, wherein at least one compound of formula I is selected from the group consisting of compounds of formula I-1, formula I-2, formula I-3, formula I-4, formula I-5, formula I-6, formula I-7, and formula I-8.

In some embodiments of the present invention, the liquid crystal composition of the present invention preferably comprises at least three compounds of formula I, wherein at least one compound of formula I is selected from the group consisting of compounds of formula I-1, formula I-2, formula I-3, formula I-4, formula I-5, formula I-6, formula I-7, and formula I-8; further preferred are compounds containing at least two compounds selected from the group consisting of compounds of the general formula I-1, the general formula I-2, the general formula I-3, the general formula I-4, the general formula I-5, the general formula I-6, the general formula I-7 and the general formula I-8.

In some embodiments of the invention, in the compound of formula M, R_M1And R_M2Independently of each other, preferably a linear alkyl group having 1 to 10 carbon atoms, a linear alkoxy group having 1 to 9 carbon atoms, or a linear alkenyl group having 2 to 10 carbon atoms; further preferably a linear alkyl group having 1 to 8 carbon atoms, a linear alkoxy group having 1 to 7 carbon atoms, or a linear alkenyl group having 2 to 8 carbon atoms; still more preferably a linear alkyl group having 1 to 5 carbon atoms, a linear alkoxy group having 1 to 4 carbon atoms, or a linear alkenyl group having 2 to 5 carbon atoms.

In some embodiments of the invention, R_M1And R_M2Each independently preferably a linear alkenyl group having 2 to 8 carbon atoms; further, each independently preferably is a linear alkenyl group having 2 to 5 carbon atoms.

In some embodiments of the present invention, preferably,R_M1and R_M2One is a linear alkenyl group having 2 to 5 carbon atoms, and the other is a linear alkyl group having 1 to 5 carbon atoms.

In some embodiments of the invention, preferably, R_M1And R_M2Both are a linear alkyl group having 1 to 8 carbon atoms or a linear alkoxy group having 1 to 7 carbon atoms; further preferably, R_M1And R_M2Both are a linear alkyl group having 1 to 5 carbon atoms or a linear alkoxy group having 1 to 4 carbon atoms.

In some embodiments of the invention, preferably, R_M1And R_M2One is a linear alkyl group having 1 to 5 carbon atoms, and the other is a linear alkyl group having 1 to 5 carbon atoms or a linear alkoxy group having 1 to 4 carbon atoms; further preferably, R_M1And R_M2Both are linear alkyl groups having 1 to 5 carbon atoms.

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

wherein denotes the carbon atom in the ring structure to which it is bonded.

The alkenyloxy group in the present invention is preferably selected from groups represented by any one of formulae (OV1) to (OV9), and particularly preferably formula (OV1), formula (OV2), formula (OV8), or formula (OV 9). The groups represented by formulae (OV1) to (OV9) are shown below:

wherein denotes the carbon atom in the ring structure to which it is bonded.

In some embodiments of the invention, the compound of formula M is selected from the group consisting of:

in some embodiments of the present invention, the content of the compound of formula M must be properly adjusted depending on desired properties such as solubility at low temperature, transition temperature, electrical reliability, birefringence, process adaptability, drop trace, burn-in, dielectric anisotropy, and the like.

The weight percentage of the compound of formula M in the liquid crystal composition of the present invention is preferably: the lower limit of the preferred weight percentage of the compound of formula M in the liquid crystal composition of the present invention is 0.1%, 1%, 10%, 20%, 30%, 40% or 50% relative to the total weight of the liquid crystal composition of the present invention; the upper limit of the preferred weight percentage of the compound of formula M in the liquid crystal composition of the present invention is 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 35% or 25% relative to the total weight of the liquid crystal composition of the present invention.

In some embodiments of the present invention, the compound of formula M is present in an amount of 0.1% to 90% by weight of the liquid crystal composition.

The content of the compound of the formula M is preferably higher in the lower limit value and higher in the upper limit value when the viscosity of the liquid crystal composition of the present invention needs to be kept low and the response time is short; when the liquid crystal composition of the present invention is required to have a high clearing point and good temperature stability, the lower limit value and the upper limit value are preferably high; in order to keep the driving voltage low and increase the absolute value of the dielectric anisotropy, it is preferable to lower the lower limit and lower the upper limit.

In some embodiments of the inventionIn the embodiment, R is preferable when importance is attached to reliability_M1And R_M2Are all alkyl; in the case where importance is attached to reduction in volatility of the compound, R is preferably_M1And R_M2Are both alkoxy groups; when importance is attached to the reduction in viscosity, R is preferably used_M1And R_M2At least one of which is alkenyl.

In some embodiments of the present invention, the compound of formula M is particularly preferably selected from the group consisting of compounds of formula M1, formula M2, formula M3, formula M4, formula M7, formula M8, formula M9, formula M10, formula M11, formula M13, formula M15, formula M16, formula M17, formula M18, formula M19, formula M20, formula M21, formula M22, formula M23 and formula M24.

In some embodiments of the present invention, the compound of formula M is preferably selected from the group consisting of compounds of formula M1, formula M2, formula M4, formula M9, formula M11, formula M13, formula M20, formula M21, formula M22, and formula M23.

In some embodiments of the invention, in the compound of formula M1, R_M1Represents a straight-chain or branched alkyl or alkoxy group having 1 to 7 carbon atoms; further preferably a straight-chain or branched alkyl group or alkoxy group having 1 to 5 carbon atoms.

Preference with respect to the compounds of the formula M1 in weight percent of the liquid crystal composition of the invention: the preferred lower limit of the weight percentage of the compound of formula M1 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 1%, 3%, 5%, 7%, 10%, 13%, 15%, 17%, 20%, 23%, 25% or 30%; the preferred upper limit of the weight percentage of the compound of formula M1 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 60%, 55%, 50%, 45%, 40%, 37%, 35%, 33%, 30%, 27%, 25%, 23%, 20%, 17%, 15%, 13% or 10%.

In order to improve in particular the response times of the liquid-crystal compositions according to the invention, preference is given to R in the compounds of the formula M1_M1Is ethyl, n-propyl, butyl or pentyl, and R_M2Is a firstCompounds of the formula M1, R_M1Is ethyl, n-propyl, butyl or pentyl, and R_M2Compounds which are ethyl or ethoxy, or compounds of the formula M1 in which R is_M1Is n-propyl, butyl or pentyl, and R_M2A compound that is n-propyl or propoxy.

R in the compound of formula M1 relative to the total weight of the liquid crystal composition of the invention_M1Is n-propyl and R_M2The preferred lower limit of the weight percentage of the compound which is an ethyl group in the liquid crystal composition of the present invention is 1%, 2%, 3%, 5%, 7%, 10%, 13%, 15%, 18% or 20%; r in the compound of formula M1 relative to the total weight of the liquid crystal composition of the invention_M1Is n-propyl and R_M2The upper limit of the preferred weight percentage of the compound which is an ethyl group in the liquid crystal composition of the present invention is 20%, 17%, 15%, 13%, 10%, 8%, 7% or 6%.

The weight percentage of the compound of formula M2 in the liquid crystal composition of the invention is preferably: the preferred lower limit of the weight percentage of the compound of formula M2 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 1%, 2%, 3%, 5%, 7% or 10%; the upper limit of the preferred weight percentage of the compound of formula M2 in the liquid crystal composition of the invention is 20%, 15%, 13%, 10%, 8%, 7%, 6%, 5% or 3% relative to the total weight of the liquid crystal composition of the invention.

The weight percentage of the compound of formula M4 in the liquid crystal composition of the invention is preferably: the preferred lower limit of the weight percentage of the compound of formula M4 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 1%, 2%, 3%, 5%, 7% or 10%; the upper limit of the preferred weight percentage of the compound of formula M4 in the liquid crystal composition of the invention is 20%, 15%, 13%, 10%, 8%, 7%, 6%, 5% or 3% relative to the total weight of the liquid crystal composition of the invention.

The weight percentage of the compound of formula M9 in the liquid crystal composition of the invention is preferably: the preferred lower limit of the weight percentage of the compound of formula M9 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 1%, 2%, 3%, 5%, 7%, 10%, 14%, 16%, 20%, 23%, 26%, 30%, 35% or 40%; the upper limit of the preferred weight percentage of the compound of formula M9 in the liquid crystal composition of the invention is 50%, 40%, 35%, 30%, 20%, 15%, 10% or 5% relative to the total weight of the liquid crystal composition of the invention.

In some embodiments of the present invention, it is preferable to contain R in the compound of the formula M9 in view of required properties of solubility at low temperature, transition temperature, electrical reliability, birefringence and the like_M1Is a linear or branched alkenyl radical having 2 to 4 carbon atoms, and R_M2Is CH₃The compound of (a), the straight-chain or branched alkenyl group having 2 to 4 carbon atoms is more preferably

R in the compound of formula M9 relative to the total weight of the liquid crystal composition of the invention_M1Is composed of

And R is_M2Is CH₃The lower limit of the weight percentage of the compound of (a) to the liquid crystal composition of the present invention is preferably 1%, 3%, 5%, 7%, 9%, 11%, 12%, 13%, 18% or 21%, and the upper limit is preferably 45%, 40%, 35%, 30%, 25%, 23%, 20%, 18%, 15%, 13%, 10% or 8%. When both the two compounds are contained, the lower limit of the weight percentage of the two compounds in the liquid crystal composition of the present invention is preferably 3%, 5%, 7%, 9%, 11%, 13%, 15%, 19%, 24%, or 30%, and the upper limit thereof is preferably 45%, 40%, 35%, 30%, 25%, 23%, 20%, 18%, 15%, 13%, 11%, or 9%, with respect to the total weight of the liquid crystal composition of the present invention.

The weight percentage of the compound of formula M10 in the liquid crystal composition of the invention is preferably: the preferred lower limit of the weight percentage of the compound of formula M10 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 1%, 2%, 3%, 4%, 5%, 7%, 10%, 14%, 16% or 20%; the preferred upper limit value of the weight percentage of the compound of formula M10 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 45%, 40%, 35%, 30%, 20%, 15%, 10% or 5%.

In some embodiments of the present invention, it is preferable to contain R in the compound of the formula M10 in view of required properties of solubility at low temperature, transition temperature, electrical reliability, birefringence and the like_M1Is a linear or branched alkenyl radical having 2 to 4 carbon atoms, and R_M2Is CH₃The compound of (a), the straight-chain or branched alkenyl group having 2 to 4 carbon atoms is more preferably

R in the compound of formula M10 relative to the total weight of the liquid crystal composition of the invention_M1Is composed of

And R is_M2Is CH₃The lower limit of the weight percentage of the compound of (a) to the liquid crystal composition of the present invention is preferably 1%, 3%, 4%, 5%, 7%, 9%, 11%, 12%, 13%, 18% or 20%, and the upper limit is preferably 40%, 35%, 30%, 25%, 23%, 20%, 18%, 15%, 13%, 10% or 8%. When both compounds are contained, the lower limit of the weight percentage of the two compounds in the liquid crystal composition of the present invention is preferably 3%, 5%, 7%, 9%, 11%, 13%, 15%, 19%, 24% or 30%, and the upper limit thereof is preferably 45%, 40%, 35%, 30%, 25%, 23%, 20%, 18%, 15% or 13%, with respect to the total weight of the liquid crystal composition of the present invention.

The weight percentage of the compound of formula M11 in the liquid crystal composition of the invention is preferably: the preferred lower limit of the weight percentage of the compound of formula M11 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 1%, 2%, 3%, 5%, 7%, 10%, 14%, 16%, 20%, 23%, 26%, 30%, 35% or 40%; the upper limit of the preferred weight percentage of the compound of formula M11 in the liquid crystal composition of the invention is 50%, 40%, 35%, 30%, 20%, 15%, 10% or 5% relative to the total weight of the liquid crystal composition of the invention.

In some embodiments of the invention, the compound of formula M11 is preferably R_M1Is n-propyl or n-pentyl, and R_M2Is C₂H₅A compound of (a), or preferably R_M1Is composed of

And R is_M2Compounds which are n-propyl, or preferably R_M1Is n-propyl, n-butyl or n-pentyl, and R_M2Is CH₃A compound of O-; particular preference is given to R_M1Is n-propyl and R_M2Is C₂H₅-a compound of (a).

The weight percentage of the compound of formula M13 in the liquid crystal composition of the invention is preferably: the preferred lower limit of the weight percentage of the compound of formula M13 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 1%, 2%, 3%, 5%, 7%, 10%, 14%, 16%, 20%, 23%, 26%, 30%, 35% or 40%; the upper limit of the preferred weight percentage of the compound of formula M13 in the liquid crystal composition of the invention is 50%, 40%, 35%, 30%, 20%, 15%, 10% or 5% relative to the total weight of the liquid crystal composition of the invention.

In some embodiments of the invention, the compound of formula M13 is preferably R_M1And R_M2Each independently represents a linear or branched alkyl group containing 2 to 5 carbon atoms, or preferably R_M1And R_M2One of them is

And the other is CH₃-or C₂H₅-a compound of (a).

The weight percentage of the compound of formula M15 in the liquid crystal composition of the invention is preferably: the preferred lower limit of the weight percentage of the compound of formula M15 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 1%, 2%, 3%, 5%, 7%, 10%, 12%, 14%, 16%, 18%, 20%, 23%, 26%, 30%, 35% or 40%; the upper limit of the preferred weight percentage of the compound of formula M15 in the liquid crystal composition of the invention is 50%, 40%, 35%, 30%, 25%, 22%, 20%, 18%, 15%, 12%, 10%, 8% or 5% relative to the total weight of the liquid crystal composition of the invention.

The weight percentage of the compound of formula M16 in the liquid crystal composition of the invention is preferably: the preferred lower limit of the weight percentage of the compound of formula M16 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 1%, 2%, 3%, 5%, 7%, 10%, 12%, 14%, 16%, 18%, 20%, 23%, 26%, 30%, 35% or 40%; the upper limit of the preferred weight percentage of the compound of formula M16 in the liquid crystal composition of the invention is 50%, 40%, 35%, 30%, 25%, 22%, 20%, 18%, 15%, 12%, 10%, 8% or 5% relative to the total weight of the liquid crystal composition of the invention.

The weight percentage of the compounds of formulae M20 to M24 in the liquid crystal composition of the present invention is preferably: a preferred lower limit value of the percentage of the compound of formulae M20 to M24 to the total weight of the liquid crystal composition of the present invention is 1%, 2%, 3%, 5%, 7%, 10%, 14%, 16% or 20%; the preferred upper limit of the percentage of the compounds of formulae M20 to M24 based on the total weight of the liquid crystal composition of the invention is 30%, 25%, 23%, 20%, 18%, 15%, 12%, 10% or 5%.

In some embodiments of the invention, the compound of formula A-1 is selected from the group consisting of:

wherein,

R_A1represents a straight-chain or branched alkyl group having 1 to 8 carbon atoms,

1 or non-adjacent 2 or more-CH in the linear or branched alkyl group containing 1 to 8 carbon atoms₂-may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-, respectively, and one or more-H present in these groups may be independently substituted by-F or-Cl, respectively;

R_vand R_wEach independently represents-CH₂-or-O-;

L_A11、L_A12、L_A11’、L_A12’、L_A14、L_A15and L_A16Each independently represents-H or-F;

L_A13and L_A13' independently of each other represents-H or-CH₃；

X_A11represents-F, -CF₃or-OCF₃(ii) a And is

v and w each independently represent 0 or 1.

The weight percentage of the compound of formula A-1 to the liquid crystal composition of the present invention is preferably: the preferred lower limit of the weight percentage of the compound of formula a-1 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 17%, 18% or 20%; the upper limit value of the compound of the general formula a-1 in the weight percentage of the liquid crystal composition of the present invention is preferably 80%, 60%, 55%, 50%, 45%, 40%, 35%, 30% or 25% with respect to the total weight of the liquid crystal composition of the present invention.

In some embodiments of the present invention, the compound of formula A-1 comprises 0.1% to 80% by weight of the liquid crystal composition.

The preferable content of the compound of the general formula A-1 is preferably such that the lower limit value is slightly lower and the upper limit value is slightly lower, when the viscosity of the liquid crystal composition of the present invention is kept low and the response speed is high; further, when the clearing point of the liquid crystal composition of the present invention is kept high and the temperature stability is good, it is preferable to make the lower limit value slightly lower and the upper limit value slightly lower; in order to increase the absolute value of the dielectric anisotropy while keeping the driving voltage low, it is preferable to increase the lower limit and the upper limit slightly.

In some embodiments of the present invention, the compound of formula A-1 is preferably selected from the group consisting of compounds of formulae A-1-7, formulae A-1-13, formulae A-1-14, and formulae A-1-15.

In some embodiments of the invention, the liquid crystal composition further comprises one or more compounds of formula A-2:

wherein,

R_A2represents a linear or branched alkyl group having 1 to 12 carbon atoms,

1 or non-adjacent 2 or more-CH in the linear or branched alkyl containing 1 to 12 carbon atoms₂-is independently substitutable by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-, respectively, and said group contains 1 to 12 carbon atomsA linear or branched alkyl group of,

Each of one or more-H may be independently substituted with-F or-Cl;

Z_A21and Z_A22Each independently represents a single bond, -CH₂CH₂-、-CF₂CF₂-、-CO-O-、-O-CO-、-O-CO-O-、-CH＝CH-、-CF＝CF-、-CH₂O-or-OCH₂-；

L_A21And L_A22Each independently represents-H, an alkyl group containing 1 to 3 carbon atoms or halogen;

X_A2represents halogen, haloalkyl or haloalkoxy having 1 to 5 carbon atoms, haloalkenyl or haloalkenyloxy having 2 to 5 carbon atoms;

ring (C)

And ring

Each independently represent

Wherein,

in at most one-CH₂-may be replaced by-O-, one or more of the ring single bonds may be replaced by double bonds,

may be substituted by-CN, -F or-Cl, and one or more rings may be substituted by-CH ═ by-N; and is

n_A2Represents 0, 1, 2 or 3, and when n_A21 and Z_A21And Z_A22When all represent single bonds, a ring

And ring

Can also represent each independently

When n is_A2When 2 or 3, ring

May be the same or different, Z_A21May be the same or different.

In some embodiments of the invention, the compound of formula a-2 is selected from the group consisting of:

wherein,

R_A2represents a linear or branched alkyl group having 1 to 8 carbon atoms, 1 or not adjacent 2 or more-CH in the linear or branched alkyl group having 1 to 8 carbon atoms₂-may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-, respectively, and one or more-H present in these groups may be independently substituted by-F or-Cl, respectively;

L_A21、L_A22、L_A23、L_A24and L_A25Each independently represents-H or-F; and is

X_A2represents-F, -CF₃、-OCF₃or-CH₂CH₂CH＝CF₂。

The weight percentage of the compound of formula A-2 to the liquid crystal composition of the present invention is preferably: the preferred lower limit of the weight percentage of the compound of formula a-2 in the liquid crystal composition of the invention relative to the total weight of the liquid crystal composition of the invention is 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 17%, 18% or 20%; the preferred upper limit of the weight percentage of the compound of formula a-2 to the liquid crystal composition of the invention is 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30% or 25% relative to the total weight of the liquid crystal composition of the invention.

In some embodiments of the invention, the compound of formula A-2 comprises 0.1% to 80% by weight of the liquid crystal composition.

The preferable content of the compound of the general formula a-2 is preferably such that the lower limit value is slightly lower and the upper limit value is slightly lower, when the viscosity of the liquid crystal composition of the present invention is kept low and the response speed is high; further, when the clearing point of the liquid crystal composition of the present invention is kept high and the temperature stability is good, it is preferable to make the lower limit value slightly lower and the upper limit value slightly lower; in order to increase the absolute value of the dielectric anisotropy while keeping the driving voltage low, it is preferable to increase the lower limit and the upper limit slightly.

In some embodiments of the present invention, the compound of formula A-2 is preferably selected from the group consisting of compounds of formula A-2-4, formula A-2-8, formula A-2-11, and formula A-2-12.

In addition to the above compounds, the liquid crystal composition of the present invention may contain a conventional nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, antioxidant, ultraviolet absorber, infrared absorber, polymerizable monomer, light stabilizer, and the like.

Possible dopants which are preferably added to the liquid crystal composition according to the invention are shown below.

In some embodiments of the present invention, preferably, the dopant comprises 0-5% by weight of the liquid crystal composition; more preferably, the dopant is present in an amount of 0-1% by weight of the liquid crystal composition.

Further, additives such as an antioxidant and a light stabilizer used in the liquid crystal composition of the present invention are preferably as follows:

wherein n represents a positive integer of 1 to 12.

Preferably, the light stabilizer is selected from the group consisting of the light stabilizers shown below:

in some embodiments of the present invention, preferably, the light stabilizer is 0 to 5% by weight of the total liquid crystal composition; more preferably, the light stabilizer is 0-1% by weight of the total liquid crystal composition; particularly preferably, the light stabilizer is 0.01 to 0.1% by weight of the total liquid crystal composition.

In some embodiments of the invention, the clearing point Cp of the liquid crystal composition is in the range of 80 to 120 ℃; the absolute value of the dielectric anisotropy Delta epsilon ranges from 3 to 12; the optical anisotropy Deltan is in the range of 0.08-0.12; ratio of vertical dielectric to dielectric epsilon_⊥The/delta epsilon is not less than 0.46; average elastic constant K_aveNot less than 13.3; at-30 deg.CAnd the low-temperature storage time is more than 500 h.

In another aspect, the invention further provides a liquid crystal display comprising the liquid crystal composition provided by the invention.

Has the advantages that:

the liquid crystal composition of the invention also has a large vertical dielectric constant epsilon under the condition of maintaining the clearing point, the optical anisotropy, the dielectric anisotropy and the low-temperature storage stability at normal levels_⊥A large vertical dielectric to dielectric ratio epsilon_⊥A large average elastic constant K_aveSmaller rotational viscosity γ 1, larger VHR (initial) and VHR (uv) and VHR (high temperature) (i.e. better reliability), and higher transmittance, so that a liquid crystal display device comprising the liquid crystal composition of the present invention has higher transmittance, higher contrast, and faster response speed, which is particularly suitable for a liquid crystal display element driven by an active matrix thin film transistor (AM-TFT).

Detailed Description

The invention will be illustrated below with reference to specific embodiments. It should be noted that the following examples are illustrative of the present invention, and are not intended to limit the present invention. Other combinations and various modifications within the spirit or scope of the present invention may be made without departing from the spirit or scope of the present invention.

In the present invention, the proportions are by weight and all temperatures are in degrees centigrade, unless otherwise specified.

For convenience of expression, in the following examples, the group structure of the liquid crystal composition is represented by the code listed in Table 1:

TABLE 1 radical structural code of liquid crystal compounds

Compounds of the following formula are exemplified:

the structural formula is represented by the code listed in Table 1, and can be expressed as: nCCGF, wherein n in the code represents the number of C atoms of the left alkyl group, for example, n is 3, namely, the alkyl group is-C₃H₇(ii) a C in the code represents cyclohexane, G represents 2-fluoro-1, 4-phenylene and F represents fluorine.

The abbreviated codes of the test items in the following examples are as follows:

cp clearing Point (nematic-isotropic phase transition temperature, ° C)

Δ n optical anisotropy (589nm, 25 ℃ C.)

ε_⊥Dielectric constant in the direction perpendicular to the molecular axis

Delta epsilon dielectric anisotropy (1KHz, 25 ℃ C.)

ε_⊥Ratio of/delta epsilon vertical dielectric to dielectric

Gamma.1 rotational viscosity (mPas, 25 ℃ C., unless otherwise stated)

LTS Low temperature storage stability (C, temperature for 500h storage without crystallization)

K₁₁Elasticity constant of splay

K₂₂Torsional elastic constant

K₃₃Flexural elastic constant

K_aveAverage elastic constant

VHR (initial) initial Voltage holding ratio (%)

Voltage holding ratio (%) after VHR (UV) UV light irradiation

Voltage holding ratio after 1 hour at VHR (high temperature) 150 ℃ at high temperature (%)

Wherein,

the optical anisotropy was measured using an Abbe refractometer under a sodium lamp (589nm) light source at 25 ℃.

Δε＝ε_‖-ε_⊥Wherein, epsilon_‖Is a dielectric constant parallel to the molecular axis,. epsilon_⊥For the dielectric constant perpendicular to the molecular axis, test conditions: the test box is TN90 type at 25 deg.C and 1KHz, and has a thickness of 7 μm.

Gamma 1 is obtained by testing a TOYO6254 type liquid crystal physical property evaluation system; the test temperature was 25 ℃, the test voltage was 90V, and the thickness of the test cell was 20 μm.

K₁₁、K₂₂、K₃₃The liquid crystal display device is obtained by using an LCR instrument and an antiparallel friction box to test a C-V curve of liquid crystal and calculating the following test conditions: a 7-micron antiparallel friction box, wherein V is 0.1-20V;

VHR (initial) was tested using the TOY06254 type liquid crystal physical property evaluation system; the test temperature was 60 ℃, the test voltage was 5V, the test frequency was 6Hz, and the thickness of the test cell was 9 μm.

VHR (UV) was measured using a TOY06254 type liquid crystal physical property evaluation system; the used wavelength is 365nm, and the energy is 6000mJ/cm²The liquid crystal material is tested after being irradiated by the UV light, the testing temperature is 60 ℃, the testing voltage is 5V, the testing frequency is 6Hz, and the thickness of a testing box is 9 mu m.

VHR (high temperature) was tested using a TOY06254 type liquid crystal physical property evaluation system; the liquid crystal was tested after being kept at 150 ℃ for 1 hour at a high temperature of 60 ℃ under a test voltage of 5V at a test frequency of 6Hz and a test cell thickness of 9 μm.

The components used in the following examples can be synthesized by a known method or obtained commercially. These synthesis techniques are conventional, and the resulting liquid crystal compounds were tested to meet the standards for electronic compounds.

Liquid crystal compositions were prepared according to the compounding ratios of the liquid crystal compositions specified in the following examples. The liquid crystal composition is prepared according to the conventional method in the field, such as heating, ultrasonic wave, suspension and the like, and is mixed according to the specified proportion.

Liquid crystal compositions given in the following examples were prepared and studied. The composition of each liquid crystal composition and the results of the performance parameter test thereof are shown below.

Comparative example 1

The liquid crystal composition of comparative example 1, which was filled between two substrates of a liquid crystal display and subjected to a performance test, was prepared with each compound and weight percentage as listed in table 2, and the test data are shown in the following table:

TABLE 2 liquid crystal composition formulations and their test properties

Example 1

The liquid crystal composition of example 1 was prepared according to the compounds and weight percentages listed in table 3, and filled between two substrates of a liquid crystal display for performance testing, and the test data are shown in the following table:

TABLE 3 liquid crystal composition formula and its test performance

As can be seen from the comparison between comparative example 1 and example 1, the liquid crystal composition of the present invention has a higher clearing point and a larger ratio ε of perpendicular dielectric to dielectric constant, while having substantially equivalent dielectric anisotropy and optical anisotropy_⊥A large average elastic constant K_aveSmaller rotational viscosity γ 1, larger VHR (initial) and VHR (uv) and VHR (high temperature) (i.e. better reliability), and better low temperature stability, which indicates that the liquid crystal composition of the present invention is more suitable for liquid crystal display devices requiring high contrast, high transmittance, fast response, and a wide nematic phase temperature range.

Comparative example 2

The liquid crystal composition of comparative example 2, which was filled between two substrates of a liquid crystal display and subjected to a performance test, was prepared with each compound and weight percentage as listed in table 4, and the test data are shown in the following table:

TABLE 4 liquid crystal composition formula and its test performance

Example 2

The liquid crystal composition of example 2 was prepared according to the compounds and weight percentages listed in table 5, and filled between two substrates of a liquid crystal display for performance testing, and the test data are shown in the following table:

TABLE 5 liquid crystal composition formulations and their test properties

As can be seen from the comparison between comparative example 2 and example 2, the liquid crystal composition of the present invention has a large vertical dielectric to dielectric ratio ε_⊥A large average elastic constant K_aveSmaller rotational viscosity γ 1, larger VHR (initial) and VHR (uv) and VHR (high temperature) (i.e. better reliability), and better low temperature stability, which indicates that the liquid crystal composition of the present invention is more suitable for liquid crystal display devices requiring high contrast, high transmittance, fast response and wide nematic phase temperature range.

Example 3

The liquid crystal composition of example 3 was prepared according to the compounds and weight percentages listed in table 6, and filled between two substrates of a liquid crystal display for performance testing, and the test data are shown in the following table:

TABLE 6 liquid crystal composition formula and its test performance

Example 4

The liquid crystal composition of example 4 was prepared according to the compounds and weight percentages listed in table 7, and filled between two substrates of a liquid crystal display for performance testing, and the test data are shown in the following table:

TABLE 7 liquid crystal composition formulations and their test properties

Example 5

The liquid crystal composition of example 5 was prepared according to the compounds and weight percentages listed in table 8, and filled between two substrates of a liquid crystal display for performance testing, and the test data are shown in the following table:

TABLE 8 liquid crystal composition formulations and their test properties

Example 6

The liquid crystal composition of example 6 was prepared according to the compounds and weight percentages listed in table 9, and filled between two substrates of a liquid crystal display for performance testing, and the test data are shown in the following table:

TABLE 9 liquid crystal composition formulations and their test properties

As is clear from the above examples, the liquid crystal composition of the present invention has a large vertical dielectric constant ε while maintaining the clearing point, the optical anisotropy, the dielectric anisotropy, and the low-temperature storage stability at normal levels_⊥Larger, thanRatio of vertical dielectric to dielectric epsilon_⊥A large average elastic constant K_aveSmaller rotational viscosity γ 1, larger VHR (initial) and VHR (uv) and VHR (high temperature) (i.e. better reliability), and higher transmittance, so that a liquid crystal display device comprising the liquid crystal composition of the present invention has higher transmittance, higher contrast, and faster response speed, which is particularly suitable for a liquid crystal display element driven by an active matrix thin film transistor (AM-TFT).

The above embodiments are merely illustrative of the technical concept and features of the present invention, and the present invention is not limited thereto, and equivalent changes and modifications made according to the spirit of the present invention should be covered thereby.

Claims

1. A liquid crystal composition, comprising:

one or more compounds of formula (I)

One or more compounds of the formula M

And one or more compounds of the formula A-1

Wherein,

Each of one or more-H may be independently substituted with-F or-Cl;

L₁、L₂、L₃、L₄、L_A11、L_A12And L_A13Each independently represents-H, an alkyl group containing 1 to 3 carbon atoms or halogen;

ring (C)

And ring

Each independently represent

Wherein,

ring (C)

Ring (C)

And ring

Each independently represent

Wherein,

one or more-CH of₂-can be replaced by-O-,

at most one-H in (a) may be substituted by halogen;

ring (C)

And ring

Each independently represent

Wherein,

May be the same or different, Z₂May be the same or different;

May be the same or different, Z_A11May be the same or different; and is

n_A12Represents 1 or 2, and when n_A12When 2, ring

May be the same or different.

2. The liquid crystal composition of claim 1, wherein when n 1-0 and n 2-1, Z is₂And Z₃At least one of which is not a single bond; when n1 is 1 and n2 is 0, Z is₁And Z₃At least one of which is not a single bond.

3. Liquid crystal composition according to claim 1 or 2, characterized in that the compound of general formula i is selected from the group consisting of:

wherein,

L₁、L₂and L₅Each independently represents-H or-F; and is

R_xAnd R_yEach independently represents-CH₂-or-O-.

4. The liquid crystal composition according to claim 3, wherein L is selected from the group consisting of the compounds of the general formulae I-1 to I-8₅represents-H.

5. The liquid crystal composition of claim 1, wherein the compound of formula i is present in an amount of 0.1% to 60% by weight of the liquid crystal composition.

6. The liquid crystal composition of claim 1, wherein the compound of formula M is selected from the group consisting of:

7. the liquid crystal composition of claim 1 or 6, wherein the compound of formula M is present in an amount of 0.1% to 90% by weight of the liquid crystal composition.

8. The liquid crystal composition of claim 1, wherein the compound of formula a-1 is selected from the group consisting of:

wherein,

R_vand R_wEach independently represents-CH₂-or-O-;

L_A13and L_A13' independently of each other represents-H or-CH₃；

X_A1represents-F, -CF₃or-OCF₃(ii) a And is

v and w each independently represent 0 or 1.

9. The liquid crystal composition of claim 1 or 8, wherein the compound of formula a-1 is present in an amount of 0.1% to 80% by weight of the liquid crystal composition.

10. The liquid crystal composition of claim 1, further comprising one or more compounds of formula a-2

Wherein,

R_A2represents a linear or branched alkyl group having 1 to 12 carbon atoms,

The straight chain containing 1 to 12 carbon atoms1 or not adjacent 2 or more-CH in chain or branched alkyl₂-said linear alkyl group containing 1 to 12 carbon atoms which may be independently replaced by-CH ═ CH-, -C ≡ C-, -O-, -CO-O-or-O-CO-, respectively,

Each of one or more-H may be independently substituted with-F or-Cl;

ring (C)

And ring

Each independently represent

Wherein,

one or more ofA plurality of-H may be substituted by-CN, -F or-Cl, and one or more rings-CH-may be replaced by-N; and is

And ring

Can also represent each independently

When n is_A2When 2 or 3, ring

May be the same or different, Z_A21May be the same or different.

11. The liquid crystal composition of claim 10, wherein the compound of formula a-2 is selected from the group consisting of:

wherein,

X_A2represents-F, -CF₃、-OCF₃or-CH₂CH₂CH＝CF₂。

12. The liquid crystal composition of claim 1 or 11, wherein the compound of formula a-2 is present in an amount of 0.1% to 80% by weight of the liquid crystal composition.

13. A display device comprising the liquid crystal composition according to any one of claims 1 to 12.