KR20140001091A - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display device is provided. The liquid crystal display device includes a first substrate, a second substrate which is separated from the first substrate and faces the first substrate, a liquid crystal layer which is arranged between the first substrate and the second substrate, a planar common electrode which is arranged between the first substrate and the liquid crystal layer, and a pixel electrode which includes a pattern to limit an opening part arranged between the common electrode and the liquid crystal layer. The liquid crystal layer includes a nematic liquid crystal with negative dielectric anisotropy, a nematic liquid crystal with positive dielectric anisotropy, and a ferroelectric liquid crystal.

Description

[0001] The present invention relates to a liquid crystal display device,

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device including a liquid crystal layer having a nematic liquid crystal and a ferroelectric liquid crystal.

Liquid crystal display devices are one of the flat panel display devices most widely used at present, and studies for high quality, high brightness, and large size are being actively conducted. As a part of the research, the structure of electrodes in the liquid crystal display device has been diversified and complicated for the high quality, high brightness and large size of the liquid crystal display device. When a driving voltage is applied to these electrodes, the arrangement of the liquid crystal molecules of the liquid crystal layer is changed by an applied electric field, and the arrangement of the liquid crystal molecules is uneven and unstable by the electrodes. Uneven and unstable arrangement of the liquid crystal molecules is caused by a problem of lowering the brightness of the liquid crystal display.

An object of the present invention is to provide a liquid crystal display device having improved luminance.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

One embodiment according to the inventive concept provides a liquid crystal display device. The liquid crystal display device includes a first substrate; A second substrate spaced apart from and facing the first substrate; A liquid crystal layer disposed between the first and second substrates; A plate-shaped common electrode disposed between the first substrate and the liquid crystal layer; And a pixel electrode having a pattern defining an opening disposed between the common electrode and the liquid crystal layer, wherein the liquid crystal layer is a nematic liquid crystal having negative dielectric anisotropy, a nematic liquid crystal having positive dielectric anisotropy, and a ferroelectric Liquid crystals.

According to an embodiment of the present invention, the liquid crystal display may be in a field fringe switching (FFS) mode.

According to another embodiment of the present invention, the liquid crystal display may further include an alignment layer disposed adjacent to the liquid crystal layer.

According to another embodiment of the present invention, the alignment layer may include a reactive mesogen material.

According to another embodiment of the present invention, the liquid crystal layer is 70% by weight to 99.9% by weight of the nematic liquid crystal having negative dielectric anisotropy and 0.1% by weight of a mixture of the nematic liquid crystal and ferroelectric liquid crystal having the positive dielectric anisotropy % To 30% by weight.

According to another embodiment of the present invention, in the mixture of the nematic liquid crystal and the ferroelectric liquid crystal having the positive dielectric anisotropy, the ferroelectric liquid crystal may comprise 10% to 99% by weight.

According to another embodiment of the present invention, the liquid crystal layer may further include a reactive mesogen material.

According to another embodiment of the present invention, the liquid crystal layer, 0.1% to 30% by weight of the mixture of the nematic liquid crystal and ferroelectric liquid crystal having the positive dielectric anisotropy, 0.01% to 3% by weight of the reactive mesogen material And nematic liquid crystals having% and excess of said negative dielectric anisotropy.

Another embodiment according to the inventive concept provides a liquid crystal display device. The liquid crystal display device includes a first substrate; A second substrate spaced apart from and facing the first substrate; A liquid crystal layer disposed between the first and second substrates; A plate-shaped common electrode disposed between the first substrate and the liquid crystal layer; And a pixel electrode having a pattern defining an opening disposed between the common electrode and the liquid crystal layer, wherein the liquid crystal layer includes a non-ferroelectric liquid crystal and a ferroelectric liquid crystal. do.

According to an embodiment of the present invention, the liquid crystal layer may include 0.1 wt% to 30 wt% of the ferroelectric liquid crystal.

According to another embodiment of the present invention, the non-ferroelectric liquid crystal may include a nematic liquid crystal having the negative dielectric anisotropy.

According to another embodiment of the present invention, the liquid crystal layer may include 70 wt% to 99.9 wt% of the nematic liquid crystal having negative dielectric anisotropy and 0.1 wt% to 30 wt% of the ferroelectric liquid crystal.

According to another embodiment of the present invention, the liquid crystal layer may further include a reactive mesogen material.

According to another embodiment of the present invention, the liquid crystal layer has 0.1 wt% to 30 wt% of the ferroelectric liquid crystal, 0.01 wt% to 3 wt% of the reactive mesogen material, and excess negative dielectric anisotropy. It may comprise a nematic liquid crystal.

According to the exemplary embodiment of the present invention, the liquid crystal display may include a liquid crystal layer including a nematic liquid crystal having negative dielectric anisotropy, a nematic liquid crystal having positive dielectric anisotropy, and ferroelectric liquid crystal molecules. By the ferroelectric liquid crystal molecules of the liquid crystal layer, alignment uniformity and stability of liquid crystal molecules in the liquid crystal layer may be improved, thereby improving brightness of the liquid crystal display.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding and assistance of the invention, reference is made to the following description, taken in conjunction with the accompanying drawings, in which:
1 is a plan view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.
2 is a cross-sectional view for describing a liquid crystal display according to an exemplary embodiment of the present invention.
3A and 3B are graphs comparing the transmittances of the liquid crystal display devices of Examples 1 to 5 and the liquid crystal display devices of Comparative Examples 1 to 5.
4A and 4B are graphs comparing the response speeds of the liquid crystal display devices of Examples 1 to 5 and the liquid crystal display devices of Comparative Examples 1 to 5. FIG.
5A to 5K are textures that change according to a voltage applied to the liquid crystal display of Example 5. FIG.
6A through 6K are textures that change according to a voltage applied to the liquid crystal display of Comparative Example 5. FIG.

In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It will be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof. Those of ordinary skill in the art will understand that the concepts of the present invention may be practiced in any suitable environment.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is to be understood that the terms 'comprises' and / or 'comprising' as used herein mean that an element, step, operation, and / or apparatus is referred to as being present in the presence of one or more other elements, Or additions.

When a film (or layer) is referred to herein as being on another film (or layer) or substrate it may be formed directly on another film (or layer) or substrate, or a third film Or layer) may be interposed.

Although the terms first, second, third, etc. have been used in various embodiments herein to describe various regions, films (or layers), etc., it is to be understood that these regions, do. These terms are merely used to distinguish any given region or film (or layer) from another region or film (or layer). Thus, the membrane referred to as the first membrane in one embodiment may be referred to as the second membrane in another embodiment. Each embodiment described and exemplified herein also includes its complementary embodiment. Like numbers refer to like elements throughout the specification.

The terms used in the embodiments of the present invention may be construed as commonly known to those skilled in the art unless otherwise defined.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[[Liquid crystal display]]

1 and 2 are a plan view and a cross-sectional view for describing a liquid crystal display according to an exemplary embodiment of the present invention.

1 and 2, the liquid crystal display device 2 may include a first substrate 100, a second substrate 200 facing the first substrate 100, and the first substrate 100. The liquid crystal layer 300 is formed between the second substrate 200. Since the first substrate 100 corresponds to a substrate on which thin film transistors are formed, the first substrate 100 is referred to as a thin film transistor substrate, and the second substrate 200 corresponds to a substrate on which color filters CF are formed.

The first substrate 100 includes a first insulating substrate 101, a plurality of gate lines, a plurality of data lines, and a plurality of pixels PXL. The first insulating substrate 101 has a substantially rectangular shape and is made of a transparent insulating material.

The gate lines extend in a first direction on the first insulating substrate 101. The gate lines are, for example, n + p gate lines GL1, ..., GLn, GLn + 1, ..., GL (n + p) -1, GLn + p.

The data lines extend in a second direction crossing the first direction with the gate lines and the insulating layer interposed therebetween. The data lines are composed of, for example, m + q data lines DL1, ..., DLm, DLm + 1, ..., DL (m + q) -1, DLm + q. Each pixel includes one of the gate lines GL1, ..., GLn, GLn + 1, ..., GL (n + p) -1, GLn + p and the data lines DL1, ... , DLm, DLm + 1, ..., DL (m + q) -1, DLm + q).

Since each pixel PXL has the same structure, in FIG. 1, an n-th gate line GLn, an m-th data line DLm, and one pixel PXL are illustrated for convenience of description.

Each pixel PXL includes a thin film transistor, a pixel electrode PE connected to the thin film transistor, a protective layer 113 covering the pixel electrode PE, and a common electrode spaced apart from the pixel electrode PE. (CE). The thin film transistor includes a gate electrode GE, a gate insulating layer 111, a semiconductor pattern SM, a source electrode SE, and a drain electrode DE.

The gate electrode GE may protrude from the n-th gate line GLn or may be provided on a portion of the n-th gate line GLn.

The gate electrode GE may be formed of a metal. The gate electrode GE may be made of nickel, chromium, molybdenum, aluminum, titanium, copper, tungsten, and an alloy thereof. The gate electrode GE may be formed of a single film or multiple films using the metal. For example, the gate electrode GE may be a triple film in which molybdenum, aluminum, and molybdenum are sequentially laminated, or a double film in which titanium and copper are sequentially laminated. Or a single film of an alloy of titanium and copper.

The gate insulating layer 111 is provided on the entire surface of the first insulating substrate 101 to cover the n-th gate line GLn and the n-th gate line GLn.

The semiconductor pattern SM is provided on the gate insulating layer 111. A portion of the semiconductor pattern SM overlaps the gate electrode GE. The semiconductor pattern SM includes an active pattern ACT provided on the gate insulating layer 111 and an ohmic contact layer OC formed on the active pattern ACT. The active pattern ACT may be formed of an amorphous silicon thin film, and the ohmic contact layer OC may be formed of n ⁺ amorphous silicon thin film. The ohmic contact layer OC is provided between a portion of the active pattern ACT and a source electrode SE to be described later, and between another portion of the active pattern ACT and a drain electrode DE to be described later. The ohmic contact layer OC makes ohmic contact between the active pattern ACT, the source electrode SE, and the drain electrode DE, respectively.

The source electrode SE is provided branched from the m-th data line DLm. The source electrode SE is formed on the ohmic contact layer OC and a portion of the source electrode SE overlaps the gate electrode GE.

The drain electrode DE is provided spaced apart from the source electrode SE with the semiconductor pattern SM therebetween. The drain electrode DE is formed on the ohmic contact layer OC, and a portion of the drain electrode DE is provided to overlap the gate electrode GE.

The source electrode SE and the drain electrode DE may be made of nickel, chromium, molybdenum, aluminum, titanium, copper, tungsten, and alloys thereof. The source electrode SE and the drain electrode DE may be formed of a single film or multiple films using the metal. For example, the source electrode SE and the drain electrode DE may be a double layer in which titanium and copper are sequentially stacked. Or a single film made of an alloy of titanium and copper.

The source electrode SE and the drain electrode DE are provided to be spaced apart from each other on the semiconductor pattern SM by a predetermined interval. Accordingly, an upper surface of the active pattern ACT between the source electrode SE and the drain electrode DE is exposed, and the source electrode SE and the drain are dependent on whether the voltage of the gate electrode GE is applied. It becomes the channel part CH which forms a conductive channel between the electrodes DE.

The pixel electrode PE is provided on the drain electrode DE and the gate insulating layer 111. The pixel electrode PE is provided directly on the portion of the drain electrode DE and the gate insulating layer 111 to directly contact the portion of the drain electrode DE and the gate insulating layer 111.

The pixel electrode PE has a substantially rectangular shape in plan view, but may be formed in various shapes depending on the shape of the pixel. The pixel electrode PE is formed as a plate without a pattern such as an opening therein.

The common electrode CE may include a pattern having an opening. According to an embodiment of the present invention, the common electrode CE may have a stripe structure extending in one direction and spaced at equal intervals from each other. In the present exemplary embodiment, the common electrode CE having the stripe structure is exemplarily described, but the structure of the common electrode CE is not limited thereto.

According to another embodiment of the present invention, the first substrate 100 may further include a first alignment layer 115 between the common electrode CE and the liquid crystal layer 300. The first alignment layer 115 may pre-tilt the liquid crystal molecules in the liquid crystal layer 300 in one direction. According to one embodiment, the first alignment layer 115 is made of poly-amic acid, polyimide, lecithin, nylon, polyvinylalcohol (PVA). It may include at least one selected from. In another embodiment, the first alignment layer 115 may further include a reactive mesogen material.

According to another embodiment of the present invention, the second substrate 200 may further include a second alignment layer 215 between the color filter CF and the liquid crystal layer 300. According to one embodiment, the second alignment layer 215 is a group consisting of poly-amic acid, polyimide, lecithin, nylon, and polyvinylalcohol (PVA). It may include at least one selected from. In another embodiment, the second alignment layer 215 may further include a reactive mesogen material.

The liquid crystal layer 300 may fill between the first and second substrates 100 and 200. According to an embodiment, the liquid crystal layer 300 may include a negative nematic liquid crytal having a negative dielectric anisotropy, a positive nematic liquid crytal having a positive dielectric anisotropy, and a ferroelectric liquid. crystal). According to another embodiment, the liquid crystal layer 300 may include a non-ferroelectric liquid crystal and a ferroelectric liquid crystal. Description of the liquid crystal layer 300 will be described in detail below.

As described above, since the liquid crystal layer 300 of the liquid crystal display device of the field fringe switching mode (FFS mode) includes the ferroelectric liquid crystal, the alignment of the liquid crystal composition together with the nematic liquid crystal can be improved and the stability of the alignment can be improved. have. Therefore, the luminance of the liquid crystal display including the liquid crystal layer 300 may be improved. In addition, by further including the reactive mesogen material in the first and second alignment layers 115 and 215, the alignment speed of the liquid crystal molecules in the liquid crystal layer 300 may be increased, and the angle of the alignment may be increased, thereby improving optical characteristics. Can be.

Hereinafter, the liquid crystal layer will be described in detail.

[ Liquid crystal layer _First Example ]

The liquid crystal layer may include a negative nematic liquid crystal having negative dielectric anisotropy, a positive nematic liquid crystal having positive dielectric anisotropy, and a ferroelectric liquid crystal.

According to an embodiment, the liquid crystal layer may include a nematic liquid crystal having negative dielectric anisotropy of about 70 wt% to about 99.9 wt%. The liquid crystal layer may further include a mixture of nematic liquid crystals and ferroelectric liquid crystals having dielectric anisotropy in an amount of about 0.1% to about 30% by weight.

The mixture of the positively anisotropic nematic liquid crystal and the ferroelectric liquid crystal includes a nematic liquid crystal having an amount of dielectric anisotropy of about 1% by weight to 90% by weight, and about 10% by weight to about 99% by weight of the ferroelectric liquid crystal. can do.

According to one embodiment, the ferroelectric liquid crystal in the liquid crystal layer may be in the range of about 0.01% to about 29.7% by weight. When the ferroelectric liquid crystal is about 0.01% by weight or less of the total amount of the liquid crystal layer, the liquid crystal alignment of the liquid crystal layer may be unstable. In addition, when the ferroelectric liquid crystal exceeds about 29.7% by weight of the total amount of the liquid crystal layer, the viscosity of the liquid crystal layer may increase, resulting in a slow response time of the display device including the liquid crystal layer. Preferably, the ferroelectric liquid crystal may be about 10% by weight of the total amount of the liquid crystal layer.

Hereinafter, exemplary materials of the nematic liquid crystal having negative dielectric anisotropy, the nematic liquid crystal having positive dielectric anisotropy and the ferroelectric liquid crystal will be described. Exemplary materials described below do not limit the nematic liquid crystals having negative dielectric anisotropy, the nematic liquid crystals having positive dielectric anisotropy, and ferroelectric liquid crystals of the present invention.

First, the characteristics of nematic liquid crystals will be briefly described, and examples of nematic liquid crystals having negative dielectric anisotropy and nematic liquid crystals having positive dielectric anisotropy will be classified.

Nematic liquid crystals form liquid crystals in which the elongated molecules of the liquid crystal have irregular positions of each other but their long axes are directed in a constant direction. Since each molecule of the nematic liquid crystal can freely move in the long axis direction, the viscosity is small and easily flows. Since the directions of the nematic molecules are substantially the same in the up and down directions, the polarization is canceled and generally does not exhibit ferroelectricity. In the direction perpendicular to the axial direction of the molecules of the liquid crystal, physical properties are very different. Therefore, nematic liquid crystal is a material having optical anisotropy. Difference between dielectric anisotropy parallel to the axial direction and dielectric anisotropy perpendicular to the axial direction (Δε is less than 0 is called nematic liquid crystal with negative dielectric anisotropy, and greater than 0 is called nematic liquid crystal with positive dielectric anisotropy do.

Negative heredity Anisotropy  Have Nematic  Liquid crystal

According to an embodiment, the nematic liquid crystal having negative dielectric anisotropy may include nematic liquid crystal molecules having negative dielectric anisotropy. In one aspect, the nematic liquid crystal molecules having negative dielectric anisotropy may be a single type. In another aspect, the nematic liquid crystal molecules having negative dielectric anisotropy may be of different kinds from each other. For example, the nematic liquid crystal molecules having negative dielectric anisotropy may include liquid crystal molecules having negative dielectric anisotropy having first dielectric anisotropy and liquid crystal molecules having negative dielectric anisotropy having second dielectric anisotropy. have. In this case, the second dielectric anisotropy may be different from the first dielectric anisotropy.

According to another embodiment, the nematic liquid crystal having negative dielectric anisotropy may include nematic liquid crystal molecules having negative dielectric anisotropy and first base liquid crystal molecules. Each of the first base liquid crystal molecules may include at least one selected from the group consisting of liquid crystal molecules having negative dielectric anisotropy, liquid crystal molecules having positive dielectric anisotropy and neutral liquid crystal molecules. In one aspect, the nematic liquid crystal having negative dielectric anisotropy may include nematic liquid crystal molecules having one kind of negative dielectric anisotropy and first base molecules. In another aspect, the nematic liquid crystal having negative dielectric anisotropy may include liquid crystal molecules having various kinds of negative dielectric anisotropy and first base liquid crystal molecules.

Hereinafter, nematic liquid crystals having negative dielectric anisotropy will be described with examples. The following materials may be used alone or in combination.

The negative liquid crystal having negative dielectric anisotropy may include a halogen group, a cyanide group, or an isocyanate group nematic liquid crystal. The nematic liquid crystal having negative dielectric anisotropy may be used alone or in combination with a halogen group, a cyanide group, or an isocyanate group nematic liquid crystal. In addition, the nematic liquid crystal having negative dielectric anisotropy may further include first base liquid crystal molecules.

The nematic liquid crystal having a halogen-based negative dielectric anisotropy may include a fluorine group, a chlorine group, or a bromine group material, and may have a single or polycyclic structure.

Nematic liquid crystals having a negative dielectric anisotropy of a halogen-based bicyclic structure may be represented by the following Chemical Formulas 1 and 2.

Formula 1

(2)

In formulas (1) and (2), R is alkyl having 1 to 15 carbon atoms, or alkoxy (wherein hydrogen may be substituted with CN, CF ₃ , or halogen, CH ₂ -group can be substituted with -CH = CH-, -O-, -CO-, -COO-, -OOC-, -O-OC-O- or -S-), X independently of each other Halogen, halogenated alkyl with 1 to 15 carbon atoms, halogenated alkoxy, halogenated alkenyl or alkenyloxy, L ¹ and L ² Are independently of each other hydrogen or halogen.

Nematic liquid crystals having a negative dielectric anisotropy of a halogen-based tricyclic structure may be represented by Chemical Formulas 3 to 6.

(3)

Formula 4

Formula 5

6

In Formulas 3 to 6, R, L ¹ , and L ² are as defined in Formulas 1 and 2, L ³ and L ⁴ are independently hydrogen or halogen, and Z is a single bond, -CF ₂ O-, -OCF _2- , -COO-, -O-CO-, -CH ₂ CH _2- , -CH = CH-, -C = C-, -CH ₂ O-,-(CH ₂ ) ₄ -, CF = CF-, -CH = CF- or -CF = CH-.

Nematic liquid crystals having a negative dielectric anisotropy of a halogen-based tetracyclic structure may be represented by Chemical Formulas 7 to 9.

Formula 7

8

Formula 9

In formulas 7 to 9, Y represents hydrogen or halogen, R ¹ represents alkyl having 1 to 15 carbon atoms, or alkenyl, and R ² represents 1 to 15 carbons Alkyl, alkenyl, or alkoxy having atoms (in R ¹ , and R ² , hydrogen may be replaced by CN, CF ₃ , or halogen atoms) , CH ₂ The group may be substituted by -O-, -S-, -C = C-, -CH = CH-, -OC-O- or -O-CO-), Z is a single bond, -CF ₂ O- , -OCF _2- , -COO-, -O-CO-, -CH ₂ CH _2- , -CH = CH-, -C = C-, -CH ₂ O-,-(CH ₂ ) _4- , CF = CF-, -CH = CF- or -CF = CH-.

The nematic liquid crystal having halogen negative dielectric anisotropy has a lateral fluorinated indane derivative and may be represented by the following Chemical Formula 10.

10

Wherein m represents an integer and n is 0 or 1.

The nematic liquid crystal having cyanide negative dielectric anisotropy may be represented by the following Chemical Formulas 11 to 13.

Formula 11

Formula 12

Formula 13

In Formulas 11-13, R ³ is an alkyl group having 1 to 15 carbon atoms, wherein hydrogen is unsubstituted or at least monosubstituted by CN, CF _{3 ,} or halogen, and CH ₂ Group can be replaced by -O-, -S-, -C = C-, -CH = CH-, -OC-O- or -O-CO-), and L ¹ and L ² independently of each other hydrogen Or halogen, Z is a single bond, -CF ₂ O-, -OCF _2- , -COO-, -O-CO-, -CH ₂ CH _2- , -CH = CH-, -C = C -, -CH ₂ O-,-(CH ₂ ) _4- , CF = CF-, -CH = CF- or -CF = CH-.

The negative liquid crystal having dielectric anisotropy may be a single substance or a mixture. According to an embodiment, the nematic liquid crystal mixture having negative dielectric anisotropy,

(a) Liquid Crystal Component A consisting of at least one compound having a dielectric anisotropy of less than -1.5:

(b) a liquid crystal component B consisting of at least one compound having a dielectric anisotropy of -1.5 to +1.5: and

(c) chiral component C may be included.

The liquid crystal component A may include one or more compounds of Formulas 14 to 17.

Formula 14

Formula 15

Formula 16

Formula 17

The liquid crystal component B may include one or more compounds of Formulas 18 to 20. The liquid crystal component B may be the first base liquid crystal molecules described above.

18

Formula 19

Formula 20

In Formulas 14 to 20, R ⁴ And R ⁵ are each independently alkyl, alkoxy, alkoxy alkyl, alkenyl or alkenyl oxy having 1 to 15 carbon atoms (wherein hydrogen May be substituted by CN, CF ₃ , or halogen atom, and -CH ₂ -group is -CH = CH-, -O-, -CO-, -COO-, -OOC-, -O- May be substituted by OC-O- or -S-), Y ¹ represents hydrogen or halogen.

Chiral component C is available in a number of chiral dopants, such as in the examples below. The choice of dopant is not important by itself.

Positive oil field Anisotropy  Have Nematic  Liquid crystal

According to an embodiment, the nematic liquid crystal having positive dielectric anisotropy may include nematic liquid crystal molecules having positive dielectric anisotropy. In one aspect, the nematic liquid crystal molecules having the positive dielectric anisotropy may be a single type. In another aspect, the nematic liquid crystal molecules having the positive dielectric anisotropy may be of different kinds from each other. For example, the nematic liquid crystal molecules having positive dielectric anisotropy may include liquid crystal molecules having positive dielectric anisotropy having first dielectric anisotropy and liquid crystal molecules having positive dielectric anisotropy having second dielectric anisotropy. have. In this case, the second dielectric anisotropy may be different from the first dielectric anisotropy.

According to another embodiment, the nematic liquid crystal having positive dielectric anisotropy may include nematic liquid crystal molecules having positive dielectric anisotropy and second base liquid crystal molecules. Each of the second base liquid crystal molecules may include at least one selected from the group consisting of liquid crystal molecules having negative dielectric anisotropy, liquid crystal molecules having positive dielectric anisotropy, and neutral liquid crystal molecules. In one aspect, the nematic liquid crystal having a positive dielectric anisotropy may include nematic liquid crystal molecules having a kind of dielectric anisotropy and second basis molecules. In another aspect, the nematic liquid crystal having positive dielectric anisotropy may include liquid crystal molecules having various kinds of dielectric anisotropy and second base liquid crystal molecules.

Hereinafter, nematic liquid crystals having positive dielectric anisotropy will be described by listing examples. The following materials may be used alone or in combination.

The nematic liquid crystal having a positive dielectric anisotropy may include a nematic liquid crystal having a positive dielectric anisotropy of a cyanide group, an isocyanate group, and a halogen group. The nematic liquid crystal having the positive dielectric anisotropy may be used alone or in combination with a cyanide group, an isocyanate group, and a halogen group positive nematic liquid crystal having the dielectric anisotropy. In addition, the nematic liquid crystal having the positive dielectric anisotropy may further include second base liquid crystal molecules.

The nematic liquid crystal having positive dielectric anisotropy may have a bicyclic structure or a tricyclic structure.

The cyanated nematic liquid crystal of the bicyclic structure may be represented by Chemical Formula 21.

Formula 21

R ⁶ in formula 21 is alkenyl having 1 to 15 carbon atoms (wherein hydrogen may be replaced by CN, CF ₃ , or halogen, and —CH ₂ — group is —CH═ May be optionally substituted by CH—, —O—, —CO—, —COO—, —OOC—, —O—OC—O—, or —S—. Specific examples of Formula 21 are shown below.

In formula 21, R ⁷ is H, CH ₃ , C ₂ H ₅ or nC ₃ H ₇ .

The nematic liquid crystal having positive dielectric anisotropy of the tricyclic structure may be represented by Chemical Formula 22.

Formula 22

R ³ is as R ³ is unsubstituted or CN, CF _3, or halogen-alkyl (alkyl) having at least one carbon atom less than the 15-substituted one by (halogen) groups as defined in formula (11) to (13) above formula, Wherein at least one CH ₂ group in these alkyls may be replaced by —O—, —S—, —C═C—, —CH═CH—, —OC—O— or —O—CO—, L ¹ and L ² is each independently hydrogen or halogen.

Nematic liquid crystals having an isocyanate-based dielectric anisotropy can be represented by the following formula (23).

Formula 23

또는

이며, B는 -CH₂-CH₂- 또는 -C=C- 이며, X¹는 수소 또는 할로겐(halogen)이며, m은 1 2,3, 또는 4이다. 화학식 23의 구체적인 예들이 다음에 도시된다.In Formula 23, R ⁸ is C _n H _{2n +1} O, C _n H _{2n +1} , or C _n H2 _{n - 1} , wherein n is 1 to 15, and A is

or

, B is -CH ₂ -CH ₂ -or -C = C-, X ¹ is hydrogen or halogen, m is 1 2,3, or 4. Specific examples of Formula 23 are shown next.

Nematic liquid crystals having a halogen-based positive dielectric anisotropy may include a fluorine-based or chlorine-based material and may have a single or polycyclic structure. Nematic liquid crystals having fluorine-based dielectric anisotropy may be represented by Chemical Formulas 24 to 27.

24

25

26

27

In Formulas 24 to 27, R ⁹ and R ¹⁰ are alkyl, alkoxy, fluorinated alkyl, fluorinated alkoxy, alkenyl having 1 to 15 carbon atoms. ), Alkenyloxy, alkoxy alkyl or fluorinated alkenyl, L ²¹ L ²² L ²³ , and L ²⁴ are each independently hydrogen or fluorine, Z Is a single bond, -CF ₂ O-, -OCF _2- , -COO-, -O-CO-, -CH ₂ CH _2- , -CH = CH-, -C = C-, -CH ₂ O-, -(CH ₂ ) _4- , CF = CF-, -CH = CF- or -CF = CH-.

The nematic liquid crystal having positive dielectric anisotropy of the halogen series bicyclic structure may be represented by the following Chemical Formula 28.

28

In Formula 28, R ¹¹ represents hydrogen, halogen, alkenyl having 1 to 15 carbon atoms, alkenyloxy, alkynyl, or alkynoxy, wherein R One or more -CH ₂ -groups at ¹¹ may be substituted with —O—, C═O or —S—, L ⁵ is halogen, fluorinated alkyl having 1 to 15 carbon atoms, alkoxy (fluorinated alkoxy), Fluorinated alkenyl, alkenyloxy or oxyalkyl, -OCF ₃ , -OCHFCF ₃ or SF ₅ , and L ⁶ , L ⁷ , L ⁸ , and L ⁹ are each independent of each other Is hydrogen (H) or halogen, Z is a single bond, -CF ₂ O-, -OCF _2- , -COO-, -O-CO-, -CH ₂ CH _2- , -CH = CH- , -C = C-, -CH ₂ O-,-(CH ₂ ) _4- , CF = CF-, -CH = CF- or -CF = CH-. Specific examples of Formula 28 are shown next.

Wherein n is 1 to 15.

The nematic liquid crystal having positive dielectric anisotropy of the halogen-based tricyclic structure may be represented by Chemical Formulas 29 to 33.

Formula 29

Formula 30

31

(32)

Formula 33

In formulas 29 to 33, R ¹² is alkyl or alkenyl having 1 to 15 carbon atoms, wherein alkyl or alkenyl is unsubstituted or at least monosubstituted by CN, CF ₃ , or halogen And one or more -CH ₂ -groups may be substituted by -O-), X ³ is -F, -Cl, -OCF ₃ , -OCHF ₂ , -OCH ₂ F or -CF ₃ . Specific examples of the formula (29) are as follows.

Here, R ¹² is as defined above.

The nematic liquid crystal having positive dielectric anisotropy of the halogen-based tetracyclic structure may be represented by Chemical Formulas 34 to 36.

Formula 34

Formula 35

Formula 36

R ¹³ in Formulas 34 to 36 are each alkyl, alkoxy or alkenyl having 1 to 15 carbon atoms (in the alkyl, alkoxy, or alkenyl, hydrogen is CN, CF ₃ , or halogen ( halogen), and the -CH ₂ -group may be substituted with -CH = CH-, -O-, -CO-, -COO-, -OOC-, -O-OC-O- or -S-. Z is a single bond, -CF ₂ O-, -OCF _2- , -COO-, -O-CO-, -CH ₂ CH _2- , -CH = CH-, -C = C-,- CH ₂ O—, — (CH ₂ ) ₄ —, CF═CF—, —CH═CF— or —CF═CH—.

A nematic liquid crystal having a positive dielectric anisotropy containing a trisubstituted fluorine or cyanide group may be represented by the formula (37).

Formula 37

In formula 37, at least one of two R ¹⁴ and R ¹⁵ is an alkenyl group having up to 15 carbon atoms unsubstituted or at least monosubstituted by CN, CF ₃ or halogen, and the other One may be an alkyl group having up to 15 carbon atoms unsubstituted or at least monosubstituted by halogen, CN _3, or halogen, wherein at least one CH ₂ of these groups The group may be replaced by -O-, -S-, -C = C-, -OCO-, or -O-CO-. Specific examples of the formula (37) are shown next.

n and m are 1 to 10, preferably 1 to 5, o and p are each independently the same or different and are 0 to 10, preferably 0 to 5, provided that the sum of o + p is preferably Is 7 or less.

The nematic liquid crystals having said positive dielectric anisotropy can be a single substance or a mixture. Nematic liquid crystal mixture having a positive dielectric anisotropy according to one embodiment,

a) liquid crystal component A consisting of one or more compounds having a dielectric anisotropy greater than +1.5,

b) a liquid crystal component consisting of one or more compounds having a dielectric anisotropy of -1.5 to +1.5, and

c) including chiral component C, if necessary;

Liquid crystal component A may include one or more compounds of Formula 37. Liquid crystal component B may include one or more compounds represented by Formula 38 below. The liquid crystal component B may be the second base liquid crystal molecules described above.

Component C is cholesteryl nonanoate (CN), S-811, S-1011, S-2011 (Merck KGaA, Darmstadt, Germany) and CB15 with a number of chiral dopants A number of commercially available chiral dopants are available, such as BDH material. The choice of dopant is not important by itself.

Formula 38

R ¹⁶ and R ¹⁷ are each independently the same or different and each is an alkyl group having up to 15 carbon atoms which are unsubstituted or at least monosubstituted by CN, CF _{3 ,} or halogen, Wherein at least one CH ₂ of these alkyl groups may be replaced by —O—, —S—, —C═C—, —CH═CH—, —OC—O— or —OCO—, wherein 1,4- The phenylene (1,4-phenylene) ring may be mono- or polysubstituted by fluorine independently of each other.

Ferroelectric liquid crystal

Although ferroelectric liquid crystals have spontaneous polarization even when an electric field is not applied, it is a kind of dielectric that is an electrically insulator, but unlike general dielectrics, dielectric polarization is not proportional to electric field, and the relationship between polarization and electric field It has the characteristic which shows the ideal with electric history. Ferroelectric liquid crystals have not only spontaneous polarization, but also physical properties in which spontaneous polarization is reversed by an electric field.

In example embodiments, the ferroelectric liquid crystal may include ferroelectric liquid crystal molecules. In one aspect, the ferroelectric liquid crystal molecules may be a single type. In another aspect, the ferroelectric liquid crystal molecules may be of different kinds from each other. For example, the ferroelectric liquid crystal molecules may include a first ferroelectric liquid crystal molecule and a second ferroelectric liquid crystal molecule. In this case, the second ferroelectric liquid crystal molecules may be different from the first ferroelectric liquid crystal molecules.

According to another embodiment, the ferroelectric liquid crystal may include ferroelectric liquid crystal molecules and third base liquid crystal molecules. Each of the third baseline liquid crystal molecules may include at least one selected from the group consisting of liquid crystal molecules having negative dielectric anisotropy, liquid crystal molecules having positive dielectric anisotropy, and neutral liquid crystal molecules. In one aspect, the ferroelectric liquid crystal may include one type of ferroelectric liquid crystal molecules and third base molecules. In another aspect, the ferroelectric liquid crystal may include ferroelectric liquid crystal molecules different from each other and third base molecules.

Hereinafter, the ferroelectric liquid crystal will be described by listing examples. The following materials may be used alone or in combination.

The ferroelectric liquid crystal may be chiral. For example, the ferroelectric liquid crystal may be a fluorine chiral end ferroelectric liquid crystal, a chiral allyl ester ferroelectric liquid crystal, a center core polyring chiral ferroelectric liquid crystal, or a smear chiral (setic chiral) ferroelectric liquid crystal and the like. In addition, the ferroelectric liquid crystal may be a banana shape ferroelectric liquid crystal. The ferroelectric liquid crystal is a fluorine chiral end ferroelectric liquid crystal, a chiral aryl ester ferroelectric liquid crystal, a center core polyring chiral ferroelectric liquid crystal, smetic chiral Ferroelectric liquid crystals and banana shape ferroelectric liquid crystals may be used alone or in combination. In addition, the ferroelectric liquid crystal may further include third base liquid crystal molecules.

The fluorine-based chiral terminal ferroelectric liquid crystal may be represented by the following Chemical Formula 39.

Formula 39

Wherein X ⁴ , X ⁵ , X ⁶ and X ⁷ are each independently CF ₃ , CF ₂ H _, CFH ₂ , halogen, alkyl or alkoxy, and C and D are independently Phenyl, mono-fluorophenyl, di-fluorophenyl, or cyclo-hexyl, E is independently a single bond, COO, OOC, and C = C And at least one of E is a single bond, q is 0 or 1, and R ¹⁸ is a terminal group represented by the following Chemical Formula 40:

Formula 40

In formula 40, Z is O, (CH ₂ ) ₁ O, or (CH ₂ ) ₂ O, J and M are independently selected from hydrogen, alkyl of 1 to 15 carbon atoms, W is a carbon atom 1 to 15 straight or branched alkyl chains, each of J, M and W different, and R ¹⁹ represents alkenyl, alkenyloxy, alkynyl containing from 1 to 15 carbon atoms ), Or alkynoxy.

The chiral aryl ester-based liquid crystal may be represented by Chemical Formula 41.

Formula 41

In Formula 41, R _a and R _b are each independently alkyl having 1 to 20 carbon atoms, Q is —C (═O) O— or —OC (═O) —, and Z is fluorine ) Represents an alkyl group substituted with alkyl or halogen, and * represents chiral carbon. Specific examples of formula 41 include 4'-n- (octyloxyphenyl4 '-(1,1,1-trifluoro-2-octyloxycarbonyl) biphenyl-4-carboxylate (4) '-n- (octyleoxyphenyl4'-(1,1,1-trigluoro-2-octyloxycarbonyl) biphenyl-4-carboxylate).

The central core polyring chiral ferroelectric liquid crystal may be represented by Chemical Formulas 42 to 44.

Formula 42

Formula 42 is formulated as S-4- (trans-4-heptylcyclohexyl) -3'-chloro-4 "-(1-methylheptyloxy) terphenyl (S-4- (trans-4-heptylcyclohexyl) -3'- chloro-4 "-(1-methylheptyloxy) terphenyl).

Formula 43

Formula 43 represents R-4-octyl-3 "-chloro-4 '' '-(1-methylhexyloxy) quaterphenyl (R-4-octhyl-3" -chloro-4' ''-(1-methylhexyloxy ) quarterphenyl).

Formula 44

Formula 44 is formulated as S-4-nonyl-3'-fluoro-4 '' '-(2-chloropropyloxy) quaterphenyl (S-4-nonyl-3'-fluoro-4' ''-(2-chloropropyloxy ) quarterphenyl).

Formula 45

Formula 45 is butyl S-2- (4-octyl-2'-fluoro-3 "-trifluoromethyl-4 '''-quaterphenyloxy) -propionate (S-2- (4-octyl- 2'-fluoro-3 "-trifluoromethyl-4 '''-quarterphenyloxy) -propionate).

The ferroelectric smectic liquid crystal may be represented by at least one of Formula 47 and Formula 48.

Formula 47

Formula 48

In formulas 47 and 48, R ²⁰ and R ²¹ each represent a linear alkyl group having 1 to 9 carbon atoms, and R ²² And R ²³ is the same or different linear alkyl of 1 to 18 carbon atoms (in R ²⁰ to R ²³ , hydrogen may be substituted by CN, CF ₃ , or halogen atom, and —CH ₂ A group may be optionally substituted by -CH = CH-, -O-, -CO-, -COO-, -OOC-, -O-OC-O- or -S-), X is hydrogen or halogen (halogen). Specific examples of Formulas 47 and 48 are shown below.

The chiral smear ferroelectric liquid crystal may be represented by Chemical Formula 49.

Formula 49

In formula 49, R ²⁴ is a chiral or achiral alkyl having 1 to 20 carbon atoms or alkenyl, R ²⁵ is a chiral or achiral alkoxy having 1 to 20 carbon atoms (alkoxy), alkenyloxy, alkylcarbonyloxy (alkyl-COO-) or alkenylcarbonyloxy (alkenyl-COO-) (in R ²⁴ and R ²⁵ , hydrogen is CN , CF ₃ , or halogen atom, and -CH ₂ -group is -CH = CH-, -O-, -CO-, -COO-, -OOC-, -O-OC- May be substituted by O- or -S-), Z ¹ is a single bond, -COO- or -OOC-, -CH ₂ CH _2- , -CH = CH-, -C = C-, -OCH ₂ -Or -CH ₂ O-, L ¹⁰ to L ¹⁴ is hydrogen, halogen, cyano, nitro, alkyl or alkenyl of 1 to 20 carbon atoms )-(CH ₂ -group can be substituted by -CH = CH-, -O-, -CO-, -COO-, -OOC-, -O-OC-O- or -S-) X ⁹ is -CH- or quality A. Specific examples of the formula 49 are shown below.

Banana-type ferroelectric liquid crystal may be represented by the following formula (50).

Formula 50

또는

이고, B1는

또는

이며, R²⁶ 및 R²⁷은 각각 독립적으로 수소 또는 할로겐(halogen)이며, R²⁸ 및 R²⁹는 독립적으로 탄소원자 8개 내지 16개의 알킬(alkyl) 또는 알콕시(alkoxy)이다. 상기 화학식 50의 구체적인 예들이 다음에 도시된다.
In Formula 50, A ¹ is

or

And B1 is

or

R ²⁶ and R ²⁷ are each independently hydrogen or halogen, and R ²⁸ and R ²⁹ are independently alkyl or alkoxy having 8 to 16 carbon atoms. Specific examples of Formula 50 are shown below.

The ferroelectric liquid crystal may be a single material of the ferroelectric liquid crystal or a mixture including the ferroelectric liquid crystal.

Formula 51

In Formula 51, X ¹⁰ is hydrogen (H), R ³⁰ is hydrogen or alkyl having 1 to 15 carbon atoms, R ³¹ is hydrogen, halogen, alkyl group having 1 to 20 carbon atoms or Alkenyl groups, where in each case one or two -CH ₂ -groups may be replaced by -O-, -C (= 0) O- or -Si (CH ₃ ) _2- At least one hydrogen of the alkyl, alkenyl group may be replaced by fluorin or CH ₃ ), and R ³² , R ³³ , R ³⁴ , and R ³⁵ are each CH ₃ .

As such, when the liquid crystal layer according to the embodiment of the present invention is applied with an electric field from the outside, the induced dipole is parallel to the electric field, and the nematic liquid crystal having negative dielectric anisotropy is arranged in a direction perpendicular to the electric field. Can be. Since the ferroelectric liquid crystal of the liquid crystal layer has a large array characteristic between molecules and an array characteristic according to an electric field, the alignment of the liquid crystal layer can be uniformly stabilized.

According to an embodiment of the present invention, the liquid crystal layer may further include a reactive mesogen material. The liquid crystal layer comprises about 0.01 wt% to about 3 wt% reactive mesogen material, about 70 wt% to about 99.9 wt% of negative dielectric anisotropy, and about 0.1 wt% of the liquid crystal layer. A mixture of nematic liquid crystals and ferroelectric liquid crystals having a positive dielectric anisotropy of% to about 30% by weight, and nematic liquid crystals having extra negative dielectric anisotropy.

The reactive mesogenic material means a polymerizable mesogenic compound. A "mesogenic compound" or "mesogenic material" may include a substance or compound comprising one or more rod-shaped, plate- or disc-shaped mesogenic groups, ie groups having the ability to induce liquid crystalline behavior. The reactive mesogen material may be a material which is polymerized by light such as ultraviolet rays and is oriented according to the alignment state of adjacent materials.

Examples of the reactive mesogen material include compounds represented by the following formula:

P1-A1- (Z1-A2) n-P2,

Wherein P1 and P2 are at least one of acrylate, methacrylate, vinyl, vinyloxy and epoxy groups, and A1 and A2 are 1,4-phenylene (phenylen) and naphthalene (naphthalene) -2,6-diyl group is at least one, Z1 is one of COO-, OCO- and a single bond, n may be one of 0, 1 and 2.

More specifically, there may be mentioned a compound represented by one of the following formulas:

Here, P1 and P2 may include at least one of acrylate, methacrylate, vinyl, vinyloxy, and epoxy groups.

According to the present exemplary embodiment, since the liquid crystal layer includes a ferroelectric liquid crystal, the alignment of the liquid crystal layer together with the nematic liquid crystal may be uniform and the stability of the alignment may be improved. In addition, since the liquid crystal layer includes a reactive mesogen material, the alignment speed of the liquid crystal layer is increased, and the angle at which the liquid crystal layer is aligned is also increased, thereby improving optical characteristics.

[ Liquid crystal layer _Second Example ]

The liquid crystal layer according to the embodiments of the present invention may include a non-ferroelectric liquid crystal and a ferroelectric liquid crystal.

According to an embodiment of the present invention, the non-ferroelectric liquid crystal may include a nematic liquid crystal having negative anisotropy. In this case, the ferroelectric liquid crystal may occupy about 0.1 wt% to about 30 wt% of the total amount of the liquid crystal layer. When the ferroelectric liquid crystal is about 0.1% by weight or less of the total amount of the liquid crystal layer, the liquid crystal alignment of the liquid crystal layer may be unstable. In addition, when the ferroelectric liquid crystal exceeds about 30% by weight of the total amount of the liquid crystal layer, the viscosity of the liquid crystal layer may increase, thereby slowing the response speed of the display device including the liquid crystal layer. Preferably, the ferroelectric liquid crystal may be about 10% by weight of the total amount of the liquid crystal layer.

In example embodiments, the liquid crystal layer may further include a reactive mesogen material. In this case, the liquid crystal layer comprises about 0.1 wt% to about 30 wt% ferroelectric liquid crystal, about 0.01 wt% to about 3 wt% reactive mesogen material, and nematic liquid crystal having extra negative dielectric anisotropy. It may include.

The components, structures, and examples of the negatively anisotropic nematic liquid crystal, the ferroelectric liquid crystal, and the reactive mesogen material described in this embodiment are substantially the same as those described above, and a detailed description thereof will be omitted.

According to another embodiment of the present invention, the non-ferroelectric liquid crystal may include a nematic liquid crystal having positive anisotropy and a nematic liquid crystal having negative anisotropy. In this case, the liquid crystal layer may include a nematic liquid crystal having negative dielectric anisotropy of about 70% by weight to about 99.9% by weight. The liquid crystal layer may further include a mixture of nematic liquid crystals and ferroelectric liquid crystals having dielectric anisotropy in an amount of about 0.1% to about 30% by weight.

The mixture of the positively anisotropic nematic liquid crystal and the ferroelectric liquid crystal includes a nematic liquid crystal having an amount of dielectric anisotropy of about 1% by weight to 90% by weight, and about 10% by weight to about 99% by weight of the ferroelectric liquid crystal. can do.

In example embodiments, the liquid crystal layer may further include a reactive mesogen material. In this case, the liquid crystal layer comprises a mixture of nematic liquid crystal and ferroelectric liquid crystal having dielectric anisotropy in an amount of about 0.1% by weight to about 30% by weight, about 0.01% by weight to 3% by weight of reactive mesogen material, Nematic liquid crystals with extra negative anisotropy.

The components, structures, and examples of the negatively anisotropic nematic liquid crystal, the positively anisotropic nematic liquid crystal, the ferroelectric liquid crystal, and the reactive mesogen material described in the present embodiment are substantially the same as those described above. The description will be omitted.

According to the present exemplary embodiment, since the liquid crystal layer includes a ferroelectric liquid crystal, the alignment of the liquid crystal layer together with the non-ferroelectric liquid crystal may be uniform and the stability of the alignment may be improved. In addition, since the liquid crystal layer includes a reactive mesogen material, the alignment speed of the liquid crystal layer may be increased, and the angle at which the liquid crystal layer is aligned may be increased, thereby improving optical characteristics.

Hereinafter, a method of manufacturing the liquid crystal layer will be briefly described.

[Production method of liquid crystal composition]

According to an embodiment of the present invention, the liquid crystal layer may be prepared by mixing a nematic liquid crystal having negative anisotropy, a nematic liquid crystal having positive dielectric anisotropy, and a ferroelectric liquid crystal. The liquid crystal layer is a mixture of a nematic liquid crystal having a negative dielectric anisotropy of about 70% by weight to about 99.9% by weight, and a nematic liquid crystal and a ferroelectric liquid crystal having a positive dielectric anisotropy of about 0.1% by weight to about 30% by weight. It can be prepared by mixing. Here, the mixture of the nematic liquid crystal having a positive anisotropy and the ferroelectric liquid crystal is a nematic liquid crystal having a dielectric anisotropy in an amount of about 1% by weight to 90% by weight, and about 10% by weight to about 99% by weight of the ferroelectric It can be prepared by mixing the liquid crystal.

In example embodiments, the liquid crystal layer may further include a reactive mesogen material. In this case, the liquid crystal layer comprises a mixture of about 0.01% to 3% by weight reactive mesogen material, a mixture of nematic liquid crystals and ferroelectric liquid crystals having dielectric anisotropy in an amount of about 0.1% to about 30% by weight, It can be prepared by mixing a nematic liquid crystal having a negative dielectric anisotropy of.

According to another embodiment of the present invention, the liquid crystal layer may be prepared by mixing a nematic liquid crystal having a negative anisotropy and a ferroelectric liquid crystal. More specifically, it may be prepared by mixing a nematic liquid crystal having a negative dielectric anisotropy of about 70% by weight to about 99.9% by weight with a ferroelectric liquid crystal of about 0.1% by weight to about 30% by weight.

In example embodiments, the liquid crystal layer may further include a reactive mesogen material. In this case, the liquid crystal layer comprises about 0.01 wt% to about 3 wt% reactive mesogen material, the 0.1 wt% to about 30 wt% ferroelectric liquid crystal, and a nematic liquid crystal having extra negative dielectric anisotropy. It can be prepared by mixing.

In the mixing process, the process temperature may be a temperature at which the largest amount of material in the liquid crystal layer exhibits isotropic characteristics. According to embodiments of the present invention, the mixing process temperature may be performed in a temperature range of about 90 ℃ to about 100 ℃. The temperature range may be a temperature range when the nematic liquid crystal having negative dielectric anisotropy exhibits isotropic characteristics. In the present embodiment, the mixing of the liquid crystal layer is performed within a temperature range of about 90 ° C. to about 100 ° C., but the present invention does not limit the mixing temperature of the liquid crystal layer.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the following examples are provided for illustrating the present invention, and the present invention is not limited by the following examples, and various modifications and changes may be made.

Liquid crystal display

≪ Example 1 >

The liquid crystal display of FIGS. 1 and 2 including a first substrate including a common electrode having a stripe pattern and a pixel electrode of a plate, a second substrate, and a liquid crystal layer filling the first and second substrates. Was prepared. The liquid crystal display is manufactured in a field fringe switching (FFS) mode.

The liquid crystal layer was made of a liquid crystal composition obtained by mixing 90% by weight of Merck's MLC 6608 (Δn = 0.084, Δε = -4.3) and 10% by weight of Kingston Chemical's KFLC 3 (Δn = 0.18) at 100 ° C. The thickness of the liquid crystal layer of the said liquid crystal display device was produced at 3.3 micrometers.

<Examples 2 to 5>

The liquid crystal display devices of Examples 2 to 5 were manufactured in the same manner except for the thickness of the liquid crystal layer of Example 1. The thickness of the liquid crystal layers of Examples 2 to 5 refer to Table 1 below.

&Lt; Comparative Example 1 &

The liquid crystal display of FIGS. 1 and 2 including a first substrate including a common electrode having a stripe pattern and a pixel electrode of a plate, a second substrate, and a liquid crystal layer filling the first and second substrates. Was prepared. The liquid crystal display is manufactured in a field fringe switching (FFS) mode.

The liquid crystal layer was prepared in 100% by weight of Merck MLC 6608 (Δn = 0.084, Δε = -4.3). The thickness of the liquid crystal layer of the said liquid crystal display device was produced at 3.3 micrometers.

&Lt; Comparative Examples 2 to 5 >

The liquid crystal display devices of Comparative Examples 2 to 5 were manufactured in the same manner except for Comparative Example 1 and the thickness of the liquid crystal layer. The thickness of the liquid crystal layers of Comparative Examples 2 to 5 refer to Table 1 below.

Liquid crystal layer Liquid crystal layer thickness
[Mu m] MLC 6608 [wt%]
(Negative nematic liquid crystal) KFLC 3 [wt%]
(Ferroelectric liquid crystal) Example 1 90 10 3.3 Example 2 90 10 3.5 Example 3 90 10 3.8 Example 4 90 10 4.0 Example 5 90 10 4.3 Comparative Example 1 100 0 3.3 Comparative Example 2 100 0 3.5 Comparative Example 3 100 0 3.8 Comparative Example 4 100 0 4.0 Comparative Example 5 100 0 4.3

Permeability evaluation

3A and 3B are graphs comparing the transmittances of the liquid crystal display devices of Examples 1 to 5 and the liquid crystal display devices of Comparative Examples 1 to 5. 3A and 3B are graphs showing transmittance according to applied voltage. 3A and 3B, the x-axis is the applied voltage, the unit is [V], and the y-axis shows the transmittance.

3A and 3B, the liquid crystal display devices of Examples 1 to 5 exhibited excellent overall transmittance as compared to Comparative Examples 1 to 5. On the basis of the same thickness of the liquid crystal layer, it can be seen that the transmittance of the liquid crystal display devices of the embodiment is generally superior to that of the liquid crystal display devices of the comparative example.

In the above evaluation, since the ferroelectric liquid crystals in the liquid crystal layers of Examples 1 to 5 guide the liquid crystal molecules to be uniformly and stably, the transmittances of the liquid crystal display devices of Examples 1 to 5 are compared to those of Comparative Examples 1 to 5 It is superior to the transmittance of the liquid crystal display device.

Response speed rating

4A and 4B are graphs comparing the response speeds of the liquid crystal display devices of Examples 1 to 5 and the liquid crystal display devices of Comparative Examples 1 to 5. FIG.

4A and 4B are graphs showing a response speed according to an applied voltage. The x-axis of FIGS. 4A and 4B is an applied voltage and a unit is [V], and a y-axis is a response speed and a unit is [ms].

4A and 4B, it can be seen that the response speed of the liquid crystal display devices of Examples 1 to 5 is not much slower than that of the liquid crystal display devices of Comparative Examples 1 to 5. In particular, as the applied voltage increases, the difference in response speed hardly occurs. Since the liquid crystal layers of Examples 1 to 5 contain ferroelectric liquid crystals, the viscosity of the liquid crystal layers is increased, which is slightly slower than the response speeds of the liquid crystal display devices of Comparative Examples 1 to 5, but appears to be similar. However, it can be seen that the response speed difference between the comparative examples and the embodiments is not so large. Accordingly, the liquid crystal layers of Examples 1 to 5 include ferroelectric liquid crystals, thereby achieving stable and uniform alignment of the liquid crystal molecules, and maintaining a response speed as before.

texture ( texture ) evaluation

5A to 5K are textures that change according to the voltage applied to the liquid crystal display of Example 5, and FIGS. 6A to 6K are textures that change according to the voltage applied to the liquid crystal display of Comparative Example 5. FIG.

5A to 5K and 6A to 6K are textures that change from a black image to a white image according to a voltage applied to the liquid crystal display. It can be seen that the textures of FIGS. 5A-5K have fewer defects, such as spots, than the textures of FIGS. 6A-6K.

In detail, FIGS. 5D and 6D are textures in which a voltage of 3 V is applied to the liquid crystal display of Example 5 and the liquid crystal display of Comparative Example 5, respectively. Looking at the texture of the liquid crystal display of FIG. 6D, a white hatched pattern is shown, but it is not shown in the texture of the liquid crystal display of FIG. 5D. The above defect can also be seen in FIG. 6E.

Looking at the above textures, in the case of the liquid crystal layer including the ferroelectric material, the alignment of the liquid crystal molecules in the liquid crystal layer is uniform and stable compared to the liquid crystal layer containing no ferroelectric material, thereby improving the brightness of the liquid crystal display device.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood. It is therefore to be understood that the above-described embodiments are illustrative and not restrictive in every respect.

100: first substrate
200: second substrate
300: liquid crystal layer

Claims (14)

A first substrate;
A second substrate spaced apart from and facing the first substrate;
A liquid crystal layer disposed between the first and second substrates;
A plate-shaped common electrode disposed between the first substrate and the liquid crystal layer; And
A pixel electrode having a pattern defining an opening disposed between the common electrode and the liquid crystal layer,
The liquid crystal layer includes a nematic liquid crystal having negative dielectric anisotropy, a nematic liquid crystal having positive dielectric anisotropy, and a ferroelectric liquid crystal. The method of claim 1,
The liquid crystal display device is a liquid crystal display device of the field fringe switching (FFS) mode. The method of claim 1,
And an alignment layer disposed adjacent to the liquid crystal layer. The method of claim 3,
The alignment layer includes a reactive mesogen material. The method of claim 1,
The liquid-
70 wt% to 99.9 wt% of the nematic liquid crystal having negative dielectric anisotropy; And
A liquid crystal display comprising 0.1 wt% to 30 wt% of a mixture of the nematic liquid crystal and the ferroelectric liquid crystal having the positive dielectric anisotropy. The method of claim 5,
In the mixture of the nematic liquid crystal having a positive dielectric anisotropy and the ferroelectric liquid crystal, the ferroelectric liquid crystal comprises 10% to 99% by weight. The method of claim 5,
The liquid crystal layer further comprises a reactive mesogen material. The method of claim 7, wherein
The liquid-
0.1% to 30% by weight of the mixture of the nematic liquid crystal and the ferroelectric liquid crystal having the positive dielectric anisotropy;
0.01 wt% to 3 wt% of the reactive mesogen material; And
A liquid crystal display comprising a nematic liquid crystal having said negative dielectric anisotropy. A first substrate;
A second substrate spaced apart from and facing the first substrate;
A liquid crystal layer disposed between the first and second substrates;
A plate-shaped common electrode disposed between the first substrate and the liquid crystal layer; And
A pixel electrode having a pattern defining an opening disposed between the common electrode and the liquid crystal layer,
The liquid crystal layer includes a non-ferroelectric liquid crystal and a ferroelectric liquid crystal. 10. The method of claim 9,
The liquid-
A liquid crystal display comprising 0.1 wt% to 30 wt% of the ferroelectric liquid crystal. 10. The method of claim 9,
The non-ferroelectric liquid crystal is,
And a nematic liquid crystal having negative dielectric anisotropy. 12. The method of claim 11,
The liquid-
70 wt% to 99.9 wt% of the nematic liquid crystal having negative dielectric anisotropy; And
Liquid crystal display comprising 0.1% to 30% by weight of the ferroelectric liquid crystal. The method of claim 12,
The liquid crystal layer further comprises a reactive mesogen material. The method of claim 13,
The liquid-
0.1 wt% to 30 wt% of the ferroelectric liquid crystal;
0.01 wt% to 3 wt% of the reactive mesogen material; And
A liquid crystal display comprising a nematic liquid crystal having said negative dielectric anisotropy.

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