KR20140001103A - Liquid crystal display device - Google Patents

Abstract

A liquid crystal display device is disclosed. The liquid crystal display device comprises: a first substrate; a second substrate facing the first substrate at a distance; a liquid crystal layer placed in between the first and the second substrates; a common electrode plate placed in between the first substrate and the liquid crystal layer; and a pixel electrode with a pattern, which limits an opening, placed in between the common electrode and the liquid crystal layer. The liquid crystal layer comprises 1-50 wt% of achiral smectic liquid crystal and extra nematic 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 smectic 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 comprises: 1 to 50% by weight of an achiral smectic liquid crystal; And extra nematic 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 nematic liquid crystal may include a negative nematic liquid crystal having negative dielectric anisotropy.

According to another embodiment of the present invention, the nematic liquid crystal may include a positive nematic liquid crystal having positive dielectric anisotropy.

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

According to another embodiment of the present invention, the chiral liquid crystal may occupy 0.01 wt% to 10 wt% in the liquid crystal layer.

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

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 comprises: 3 to 50 wt% smectic liquid crystal; And an extra nematic liquid crystal, wherein the smectic liquid crystal comprises: 70 to 97% by weight of a non-chiral smectic liquid crystal; And 3 to 30% by weight of a chiral smectic liquid crystal.

According to an embodiment of the present invention, the liquid crystal layer may further include a chiral dopant.

According to another embodiment of the present invention, the chiral smectic liquid crystal may have a higher spontaneous polarization characteristic than the chiral dopant.

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

According to another embodiment of the present invention, the nematic liquid crystal may include a nematic liquid crystal having positive dielectric anisotropy.

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, further comprising an alignment layer disposed adjacent to the liquid crystal layer, the alignment layer may include a reactive mesogen material.

According to the exemplary embodiment of the present invention, the liquid crystal display may include a liquid crystal layer having a nematic liquid crystal and a non-chiral smectic liquid crystal. In addition, the liquid crystal layer according to the embodiment of the present invention may further include a chiral liquid crystal. In the liquid crystal display including the liquid crystal layer, alignment uniformity and stability of liquid crystal molecules in the liquid crystal layer may be improved to improve transmittance 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 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.
3 is a graph comparing transmittances of the liquid crystal display of Comparative Examples and Examples 1 to 7 according to the applied voltage.
4A is a graph showing the transmittance of the liquid crystal display of the comparative example and the transmittance according to the amount of non-chiral component in the liquid crystal layer of the liquid crystal display of Examples 1 to 7. FIG.
4B is a graph showing the transmittance of the liquid crystal display of the comparative example and the transmittance according to the amount of chiral components in the liquid crystal layer of the liquid crystal display of Examples 1 to 7.
FIG. 5A is a graph comparing the response speeds of the liquid crystal displays of Comparative Examples and Examples 1 to 7. FIG.
5B is a graph illustrating the rising time and the polling time of the liquid crystal display of the comparative example, and the rising time and the polling time of the liquid crystal display of Examples 1 to 7 according to the amount of non-chiral component.
5C is a graph illustrating a rising time of the comparative example and the liquid crystal display devices of Examples 1 to 7 according to the applied voltage.
5D is a graph illustrating a comparison time and polling times of liquid crystal display devices of Examples 1 to 7 according to applied voltage.
6A through 6H and 7A through 7H are textures of the liquid crystal display of Comparative Example and Embodiments 1 through 7.
8A and 8B are graphs showing transmittances according to distances of the textures of Comparative Examples and Examples 1 to 7. FIG.
9A and 9B are graphs showing transmittances according to distances of the textures of Comparative Examples and Examples 1 to 7. 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 according to the embodiments of the present invention may include a nematic liquid crystal and a non-chiral smectic liquid crystal.

The liquid crystal layer may include about 1 wt% to about 50 wt% non-chiral smectic liquid crystal and about 50 wt% to about 99 wt% nematic liquid crystal. When the non-chiral smectic liquid crystal is about 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 non-chiral smectic liquid crystal exceeds about 50% by weight of the total amount of the liquid crystal layer, the viscosity of the liquid crystal layer may increase, thereby reducing the response time of the display device including the liquid crystal layer. More preferably, the liquid crystal layer may include about 1% by weight to about 35% by weight of a non-chiral smectic liquid crystal.

According to one embodiment, the amount of non-chiral smectic liquid crystal in the liquid crystal layer may be determined by the viscosity of the non-chiral smectic liquid crystal. When the viscosity of the non-chiral smectic liquid crystal is low, the non-chiral smectic liquid crystal in the liquid crystal layer may include about 50% by weight or more. On the other hand, when the viscosity of the non-chiral smectic liquid crystal is high, it may be desirable to maintain the total viscosity of the liquid crystal layer at about 35% by weight or less.

According to an embodiment, the nematic liquid crystal may include a negative nematic liquid crystal having negative dielectric anisotropy. According to another embodiment, the nematic liquid crystal may include a nematic liquid crystal having negative anisotropy and a positive nematic liquid crystal having positive dielectric anisotropy. The nematic liquid crystal having the positive dielectric anisotropy may occupy about 10% by weight of the nematic liquid crystal.

Hereinafter, exemplary materials of the nematic liquid crystal and the non-chiral smectic liquid crystal will be described. The exemplary materials described below do not limit the nematic liquid crystal and the non-chiral smectic liquid crystal of the present invention to this.

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. If the difference between the dielectric anisotropy parallel to the axial direction and the dielectric anisotropy perpendicular to the axial direction (Δε) is less than zero, it is called a nematic liquid crystal with negative dielectric anisotropy. It is called.

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 first dielectric anisotropy and liquid crystal molecules having second dielectric anisotropy. In this case, the second dielectric anisotropy may be different from the first dielectric anisotropy. At least one of the first dielectric anisotropy and the second dielectric anisotropy may have dielectric anisotropy having negative anisotropy. The overall dielectric anisotropy of the nematic liquid crystal molecules including the liquid crystal molecules having the first dielectric anisotropy and the liquid crystal molecules having the second dielectric anisotropy may be negative.

According to another embodiment, the nematic liquid crystal having negative dielectric anisotropy may include nematic liquid crystal molecules and base liquid crystal molecules having negative dielectric anisotropy. Each of the 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, neutral liquid crystal molecules, chiral liquid crystal molecules, and non-chiral liquid crystal molecules. Can be. 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 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 base liquid crystal molecules.

Hereinafter, examples of nematic liquid crystals having negative dielectric anisotropy will be listed and described. 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. As described above, the nematic liquid crystal having negative dielectric anisotropy may further include 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, and 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 may 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 18 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 chiral 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 the positive dielectric anisotropy may include liquid crystal molecules having the first dielectric anisotropy and liquid crystal molecules having the second dielectric anisotropy. In this case, the second dielectric anisotropy may be different from the first dielectric anisotropy. At least one of the first dielectric anisotropy and the second dielectric anisotropy may have dielectric anisotropy having positive anisotropy. The overall dielectric anisotropy of the nematic liquid crystal molecules including the liquid crystal molecules having the first dielectric anisotropy and the liquid crystal molecules having the second dielectric anisotropy is sufficient to have a positive dielectric property.

According to another embodiment, the nematic liquid crystal having positive dielectric anisotropy may include nematic liquid crystal molecules and base liquid crystal molecules having positive dielectric anisotropy. Each of the 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, neutral liquid crystal molecules, chiral liquid crystal molecules, and non-chiral liquid crystal molecules. Can be. 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 base molecules. In another aspect, the nematic liquid crystal having positive dielectric anisotropy may include liquid crystal molecules having various kinds of dielectric anisotropy, and 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 substituted by CN, CF ₃ , or halogen, and the —CH ₂ — group is —CH═CH—, —O—, —CO—, —COO—, —OOC— , Which may be optionally substituted by -O-OC-O- or -S-.

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, wherein One or more CH ₂ groups in these alkyls may be replaced by —O—, —S—, —C≡C—, —CH═CH—, —OC—O— or —O—CO—, L ¹ and L ² each independently is hydrogen or halogen (halogen) with each other.

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 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), R-811, S-811, S-1011, S-2011 (Merck KGaA, Darmstadt, Germany) with a number of chiral dopants; Many chiral dopants on the market are available, such as CB15 (BDH, Poole, UK). 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 one or more CH ₂ in 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.

B-chiral Smectic  Liquid crystal

Smectic liquid crystals are found at lower temperatures than nematic liquid crystals, and rod-shaped liquid crystals form a layered structure so that the liquid crystals are arranged in parallel with each other. In the plane of the layer, there is no regularity in the position of the liquid crystal, but the positional order of the liquid crystal position is maintained in the direction perpendicular to the plane. The bonds between the molecular layers are relatively weak and have a slippery property. Because of this, smectic liquid crystals exhibit the properties of two-dimensional fluids. However, the viscosity is very high compared to ordinary liquids.

The non-chiral smectic liquid crystal may have various structures depending on the liquid crystal arrangement. In one example, Smectic A liquid crystal is arranged perpendicular to the molecular plane (plane). In another example, the Smectic C liquid crystal is arranged at an angle with the molecular layer. In another example, Smectic B is arranged perpendicular to the molecular layer but the liquid crystals are arranged in a hexagonal network within the layer. The types of smectic liquid crystals are various, and the types of smectic liquid crystals in the present invention are not limited to those described above.

According to one embodiment, the non-chiral smectic liquid crystal may include non-chiral smectic liquid crystal molecules. In one aspect, the non-chiral smectic liquid crystal molecules may be a single type. In another aspect, the non-chiral smectic liquid crystal molecules may be of different types from each other. For example, the non-chiral smectic liquid crystal molecules may include a first non-chiral smectic liquid crystal molecule and a second non-chiral smectic liquid crystal molecule. In this case, the second non-chiral smectic liquid crystal molecule may be different from the first non-chiral smectic liquid crystal molecule.

According to another embodiment, the non-chiral smectic liquid crystal may include non-chiral smectic liquid crystal molecules and base liquid crystal molecules. Each of the 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 non-chiral smectic liquid crystal may include one kind of non-chiral smectic liquid crystal molecules and base molecules. In another aspect, the non-chiral smectic liquid crystal may include different non-chiral smectic liquid crystal molecules and base molecules.

Hereinafter, the non-chiral smectic liquid crystal will be described by listing examples. The following materials may be used alone or in combination. The non-chiral smectic liquid crystal may include a smectic A liquid crystal, a smectic B liquid crystal, a smectic C liquid crystal, and the like.

Smectic A liquid crystal may be represented by the following formula 39 to 41.

Formula 39

Formula 40

Here, 1≤n≤15.

Formula 41

CH ₂ = C (CH ₃ ) COO (CH ₂ ) ₅ PhCOOPhPhCF ₃

Here, Ph is a 1, 4-phenylene group.

The smectic B liquid crystal may comprise 4-hexyl-4 '-[2- (4-isothiocyanatophenyl) ethyl] -1-1'-biphenyl, between 60.3 and 98.5 ° C. In addition, the smectic B liquid crystal is 1- [5- (4-hexylphenyl) pyramidyl-2] -2- (4-hexyloxyphenyl) ethane, PhPhCHNPhCHCHCOOCH ₂ CH (CH ₃ ) ₂ , C ₆ H ₁₃ OPhCHNPhPh, C ₈ H ₁₇ OPhPhCOOPhOC ₅ H ₉ , C ₈ H ₁₇ PhPhCOOPhC ₈ H ₁₇ , C ₈ H ₁₇ OPhPhCOOPhOC ₇ H ₁₇ , C ₅ H _{11 It} may comprise at least one selected from the group consisting of OPhCHNPhPh and C ₁₆ H ₃₃ OPhCHNPhPh.

Smectic C liquid crystal may be represented by the following Chemical Formulas 42 to 44.

Dialogue 42

Here, each of A and B is a benzene ring or a cyclo nucleic acid ring, m and n are 0 or 1, and each of R ₁ and R ₂ is an alkyl group, an alkoxy group or an alkanoyloxy group having 1 to 18 carbons.

Formula 43

Here, each of R ₃ and R ₄ is an alkyl group having 1 to 18 carbons.

Formula 44

Wherein X is cobalt bond or -O-, n is 0 to 10, R ₅ is an alkyl group or alkoxy group having 1 to 18 carbons, and R ₆ is an alkyl group having 2 to 18 carbons.

According to the present embodiment, since the liquid crystal layer includes a nematic liquid crystal and a non-chiral smectic liquid crystal, the alignment of the liquid crystal layer may be uniform and the stability of the alignment may be improved.

According to another embodiment of the present invention, the liquid crystal layer may further include a chiral liquid crystal. The liquid crystal layer may include a chiral liquid crystal, a non-chiral smectic liquid crystal, and a nematic liquid crystal. In the liquid crystal layer, the total amount of the chiral liquid crystal and the non-chiral smectic liquid crystal may account for about 1% by weight to about 50% by weight. For example, the chiral liquid crystal may occupy about 0.01 wt% to 10 wt% in the liquid crystal layer.

According to one aspect, the chiral liquid crystal may include chiral liquid crystal molecules. For example, the chiral liquid crystal molecules may be one kind. As another example, the chiral liquid crystal molecules may be of different types. For example, the chiral liquid crystal molecules may include chiral liquid crystal molecules having spontaneous polarization and chiral liquid crystal molecules having no spontaneous polarization. In addition, the chiral liquid crystal molecules may include chiral liquid crystal molecules having different spontaneous polarization characteristics.

According to another aspect, the chiral liquid crystal may function as a ferroelectric material together with the non-chiral smectic 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.

Hereinafter, examples of the chiral liquid crystals will be listed and described. In the present invention, the chiral liquid crystal is not limited to the following materials.

The chiral liquid crystal may be a fluorine chiral end liquid crystal, a chiral allyl ester liquid crystal, a center core polyring chiral liquid crystal, or a chiral smectic. Liquid crystal and the like. In addition, the chiral liquid crystal may be a banana shape liquid crystal.

Fluorine-based chiral terminal liquid crystal may be represented by the formula (45).

Formula 45

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 cyclohexyl, E is independently a single bond, COO, OOC, and C≡C Is selected from at least one of E is a single bond, q is 0 or 1, and R ¹⁸ is a terminal group of the formula (40).

Formula 46

In formula 46, 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 liquid crystal may be represented by Formula 47.

Formula 47

In Formula 47, R _a and R _b are each independently alkyl having 1 to 20 carbon atoms, Q is -C (= 0) O- or -OC (= 0), 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 liquid crystal may be represented by Chemical Formulas 48 to 51.

Formula 48

Formula 48 is S-4- (trans-4-heptylcyclohexyl) -3'-chloro-4 "-(1-methylheptyloxy) terphenyl (S-4- (trans-4-heptylcyclohexyl) -3'- chloro-4 "-(1-methylheptyloxy) terphenyl).

Formula 49

Formula 49 is R-4-octyl-3 "-chloro-4 '' '-(1-methylhexyloxy) quaterphenyl (R-4-octhyl-3" -chloro-4' ''-(1-methylhexyloxy ) quarterphenyl).

Formula 50

Chemical Formula 50 is S-4-nonyl-3'-fluoro-4 '' '-(2-chloropropyloxy) quaterphenyl (S-4-nonyl-3'-fluoro-4' ''-(2-chloropropyloxy ) quarterphenyl).

Formula 51

Formula 51 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 chiral liquid crystal may be represented by at least one of Chemical Formulas 52 and 53.

Formula 52

Formula 53

In Formulas 52 and 53, 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 52 and 53 are shown next.

The chiral smectic liquid crystal may be represented by Chemical Formula 54.

54

In formula 54, R ²⁴ is a chiral or achiral alkyl or alkenyl having 1 to 20 carbon atoms, 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- 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 Soyida. Specific examples of the formula 49 are shown below.

Banana type chiral liquid crystal may be represented by the formula (55).

55

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 55, 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 chiral liquid crystal may be a single material of the chiral liquid crystal or a mixture including the chiral liquid crystal.

Formula 56

In formula 56, X ¹⁰ is hydrogen (H), R ³⁰ is hydrogen or alkyl of 1 to 15 carbon atoms, R ³¹ is hydrogen, halogen, alkyl group of 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 fluorine or CH ₃ ), and R ³² , R ³³ , R ³⁴ , and R ³⁵ are each CH ₃ .

According to the present embodiment, since the liquid crystal layer includes a nematic liquid crystal and a non-chiral smectic liquid crystal, the alignment of the liquid crystal layer may be uniform and the stability of the alignment may be improved. In addition, when the liquid crystal layer contains a chiral liquid crystal, ferroelectric characteristics can be expressed together with the non-chiral smectic liquid crystal, so that the alignment of the liquid crystal layer can be made more uniform and the stability of the alignment can be further improved.

According to another embodiment of the present invention, the liquid crystal layer may further include a reactive mesogen material. The liquid crystal layer may include about 0.01% to about 3% by weight reactive mesogen material, about 1% to about 50% by weight of a non-chiral smectic liquid crystal and an extra nematic liquid crystal.

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 embodiment, since the liquid crystal layer includes a nematic liquid crystal and a non-chiral smectic liquid crystal, the alignment of the liquid crystal layer 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.

According to another embodiment of the present invention, the liquid crystal layer may include a non-chiral liquid crystal, a nematic liquid crystal, a chiral liquid crystal and a reactive mesogen material. In the liquid crystal layer, the total amount of the non-chiral smectic liquid crystal and the chiral liquid crystal may account for about 1% by weight to about 50% by weight. The chiral liquid crystal of the liquid crystal layer may occupy about 0.01% by weight to 10% by weight. The reactive mesogen material may comprise about 0.01 wt% to about 3 wt% of the liquid crystal layer.

See above for details of the non-chiral liquid crystal, nematic liquid crystal, chiral liquid crystal and reactive mesogen material.

According to the present embodiment, the liquid crystal layer includes the non-chiral liquid crystal, the nematic liquid crystal, and the chiral liquid crystal, so that the alignment of the liquid crystal layer can be uniform and the stability of the alignment can 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.

[[ Liquid crystal layer _Second Example ]]

The liquid crystal layer according to the embodiments of the present invention may include a nematic liquid crystal and a smectic liquid crystal. The liquid crystal layer may include about 50 wt% to about 97 wt% nematic liquid crystal, and about 3 wt% to about 50 wt% smectic liquid crystal. When the smectic liquid crystal is less than about 3% by weight of the liquid crystal layer, the liquid crystal alignment of the liquid crystal layer may be unstable. In addition, when the smectic liquid crystal exceeds about 50% 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. More preferably, the liquid crystal layer may include about 3% by weight to about 35% by weight smectic liquid crystal.

The amount of smectic liquid crystal in the liquid crystal layer may be determined by the viscosity of the smectic liquid crystal. When the viscosity of the smectic liquid crystal is low, the smectic liquid crystal in the liquid crystal layer may include about 50% by weight or more. On the other hand, when the viscosity of the smectic liquid crystal is high, in consideration of the overall viscosity of the liquid crystal layer, it may be desirable to maintain at about 30% by weight or less.

According to an embodiment of the present invention, the smectic liquid crystal may include a non-chiral smectic liquid crystal and a chiral smectic liquid crystal. The smectic liquid crystal may include about 70 wt% to about 97 wt% non-chiral smectic liquid crystal and about 3 wt% to about 30 wt% chiral smectic liquid crystal.

The chiral smectic liquid crystal may have a spontaneous polarization characteristic. Spontaneous polarization refers to a phenomenon in which a material is electrically polarized in a natural state without an electric field applied. The chiral smectic liquid crystal will be described later in detail.

According to an embodiment, the nematic liquid crystal may include a nematic liquid crystal having negative dielectric anisotropy. According to another embodiment, the nematic liquid crystal may include a nematic liquid crystal having negative anisotropy and a nematic liquid crystal having positive dielectric anisotropy. The nematic liquid crystal having the positive dielectric anisotropy may occupy about 10% by weight of the nematic liquid crystal.

The components, structures, and examples of the non-chiral smectic liquid crystals of the nematic liquid crystal and the smectic liquid crystal described in this embodiment are substantially the same as those described above, and thus the detailed description thereof will be omitted.

Hereinafter, the chiral smectic liquid crystal will be described in more detail.

The chiral smectic liquid crystal may include chiral smectic liquid crystal molecules. According to one aspect, chiral smectic liquid crystal molecules may be one kind. In another aspect, the chiral smectic liquid crystals may be of different types from each other. For example, chiral smectic liquid crystal molecules may include a first chiral smectic liquid crystal molecule and a second chiral smectic liquid crystal molecule. The first and second chiral smectic liquid crystal molecules may be different from each other.

According to another embodiment, the chiral smectic liquid crystal may include chiral smectic liquid crystal molecules and base liquid crystal molecules. The 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, neutral liquid crystal molecules, and non-chiral liquid crystal molecules.

According to another embodiment, the chiral smectic liquid crystal may cause the liquid crystal layer to exhibit ferroelectric characteristics together with the non-chiral liquid crystal molecules.

Chiral smectic liquid crystals include chiral smectic C liquid crystals and other chiral smectic liquid crystals.

Chiral Smectic C may be represented by Formula 57 to Formula 60.

(57)

또는

or

58

그룹이고, R'은 1 내지 4개의 탄소를 갖는 알킬 그룹이고, T는

이고, X는 적어도 하나의 카이럴 중심을 갖는 알킬 또는 할로겐 치환 알킬 그룹이며, Y는 불소 원자 이며, m는 0, 1 또는 2를 가지며, p는 2, 3 또는 4를 가지며, n는 10, 11 또는 12를 갖는다.
In formula (57) and formula (58), R is an alkyl group having 1 to 10 carbons, or

Is a group, R 'is an alkyl group having from 1 to 4 carbons, and T is

X is an alkyl or halogen substituted alkyl group having at least one chiral center, Y is a fluorine atom, m has 0, 1 or 2, p has 2, 3 or 4, n is 10, Has 11 or 12.

59

In formula 59, R ¹ and R ² are linear alkyl groups containing 1 to 9 carbons and are different from each other.

60

In formula 60, R ³ and R ⁴ are alkyl groups containing 1 to 18 carbons, the same or different from each other, and X is hydrogen or fluorine.

61

In formula 61, l is 1 or 2, and Y is —COO—, —CH═N—, —CH ₂ O—, —OCO—, —N═CH—, —OCH 2 — or a single link, R ¹⁰ Is an alkyl or alkoxy group having 1 to 18 valent carbons, R ¹¹ is (S) -2-methylbutyl, (S) -2-methylbutoxy, (S) -2-methylbutoxycarbonyl, (S) -1-methylheptyloxy, (R) -1-methylheptyloxy, (S) -1-methylheptyloxycarbonyl or (R) -1-methylheptyloxycarbonyl.

(62)

그룹을 포함한다.In formula 62, n is 1 or 2, R is an alkyl or alkoxy group containing 1 to 18 carbons, Y is an alkyl, alkoxy, aloxycarbonyl, alkanoyl or alkanoyloxy group having an asymmetric carbon, X is

Group.

In formula 62, Y is

,

,

,

,

,

그룹 중 하나일 수 있다.

,

,

,

,

,

It can be one of the groups.

According to the present embodiment, since the liquid crystal layer includes a nematic liquid crystal, a non-chiral smectic liquid crystal and a chiral smectic liquid crystal, the alignment of the liquid crystal layer may be uniform and the stability of the alignment may be improved.

According to another embodiment of the present invention, the liquid crystal layer may further include a chiral dopant. The chiral dopant may be included in about 10% by weight or less in the liquid crystal layer. According to one aspect, the chiral dopant may have no spontaneous polarization characteristics. According to another aspect, the chiral dopant may have a lower spontaneous polarization characteristic than the chiral smectic liquid crystal.

According to an embodiment, the chiral dopant may include a plurality of chiral dopants. According to one aspect, the chiral dopants may be one kind. According to another aspect, the chiral dopants may be of different types from each other.

According to another embodiment, the chiral dopant may exhibit ferroelectric properties with the smectic liquid crystal.

Hereinafter, examples of the chiral dopant will be listed and described. The following materials may be used alone or in combination. In addition, the chiral dopant in the present invention is not limited to the following materials.

The chiral dopant may be at least one selected from Chemical Formulas 63 to 70.

Formula 63

(64)

(65)

66

(67)

68

Formula 69

70

In Chemical Formulas 66 to 70, R ^K Is an alkyl group containing 3 to 10 carbons, in which the -CH ₂ -adjacent to the ring in the alkyl can be replaced with -O-, and any -CH ₂ -can be replaced by -CH-CH- .

Cholesteryl nonanoate (CN), R-811, S-811, S-1011, S-2011 (Merck KGaA, Darmstadt, Germany) with chiral dopants and CB15 (Full, UK) Many chiral dopants, such as BDH), are available.

According to the present embodiment, since the liquid crystal layer includes a nematic liquid crystal, a non-chiral smectic liquid crystal and a chiral smectic liquid crystal, the alignment of the liquid crystal layer may be uniform and the stability of the alignment may be improved. In addition, since the liquid crystal layer further includes a chiral dopant, ferroelectric characteristics can be expressed together with the smectic liquid crystal, thereby making the alignment of the liquid crystal layer more uniform and the stability of the alignment further improved.

According to another embodiment of the present invention, the liquid crystal layer may further include a reactive mesogen material. The liquid crystal layer may include about 0.01 wt% to about 3 wt% of reactive mesogen material. Detailed description of the reactive mesogen material will be omitted.

According to the present embodiment, since the liquid crystal layer includes a nematic liquid crystal, a non-chiral smectic liquid crystal and a chiral smectic liquid crystal, the alignment of the liquid crystal layer 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.

According to another embodiment of the present invention, the liquid crystal layer may include a nematic liquid crystal, a smectic liquid crystal, a chiral dopant and a reactive mesogen material. The liquid crystal layer may include about 3 wt% to about 50 wt% smectic liquid crystal, about 10 wt% or less chiral dopant, and about 0.01 wt% to about 3 wt% reactive mesogen material. Detailed descriptions of the nematic liquid crystal, smectic liquid crystal, chiral dopant and reactive mesogen materials will be omitted.

According to the present embodiment, the liquid crystal layer may include a nematic liquid crystal, a non-chiral smectic liquid crystal, a chiral smectic liquid crystal, and a chiral dopant, thereby making the alignment of the liquid crystal layer uniform and improving stability of the alignment. 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.

[[ The liquid crystal layer  Manufacturing Method]]

According to an embodiment of the present invention, the liquid crystal layer may be prepared by mixing a nematic liquid crystal and a non-chiral smectic liquid crystal. The liquid crystal layer may be prepared by mixing about 50 wt% to about 99 wt% of nematic liquid crystal and about 1 wt% to about 50 wt% of a non-chiral smectic liquid crystal.

According to one aspect, the liquid crystal layer may further include a chiral liquid crystal. The liquid crystal layer may be prepared by mixing about 10 wt% or less of chiral liquid crystals, about 1 wt% to about 50 wt% of non-chiral smectic liquid crystals, and excess nematic liquid crystals.

According to another aspect, the liquid crystal layer may further include a reactive mesogen material. The liquid crystal layer may be prepared by mixing about 0.01% to about 3% by weight reactive mesogen material, about 1% to about 50% by weight of a non-chiral smectic liquid crystal and an extra nematic liquid crystal. .

According to another aspect, the liquid crystal layer may include a nematic liquid crystal, a non-chiral smectic liquid crystal, a chiral liquid crystal and a reactive mesogen material. The liquid crystal layer comprises about 0.01 wt% to about 3 wt% reactive mesogen material, about 10 wt% or less chiral liquid crystal, about 1 wt% to about 50 wt% non-chiral smectic liquid crystal, and The nematic liquid crystal can be mixed and produced.

According to another embodiment of the present invention, the liquid crystal layer may be prepared by mixing nematic liquid crystal and smectic liquid crystal. The liquid crystal layer may be prepared by mixing about 50 wt% to about 97 wt% nematic liquid crystal and about 3 wt% to about 50 wt% smectic liquid crystal. The smectic liquid crystal may include a non-chiral smectic liquid crystal and a chiral smectic liquid crystal. The smectic liquid crystal may include about 70 wt% to about 97 wt% non-chiral smectic liquid crystal and about 3 wt% to about 30 wt% chiral smectic liquid crystal.

According to one aspect, the liquid crystal layer may further include a chiral dopant. The liquid crystal layer may be prepared by mixing about 10% by weight or less of chiral dopant, about 3% by weight to about 50% by weight smectic liquid crystal and excess nematic liquid crystal.

According to another aspect, the liquid crystal layer may further include a reactive mesogen material. The liquid crystal layer may be prepared by mixing about 0.01 wt% to about 3 wt% reactive mesogen material, about 3 wt% to about 50 wt% smectic liquid crystal, and excess nematic liquid crystal.

According to another aspect, the liquid crystal layer may include nematic liquid crystal, smectic liquid crystal, chiral dopant and reactive mesogen material. The liquid crystal layer comprises less than about 10 wt% chiral dopant, about 0.01 wt% to about 3 wt% reactive mesogen material, about 3 wt% to about 50 wt% smectic liquid crystal and extra nematic liquid crystal. 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 exhibits isotropic characteristics. In the present embodiment, the mixing of the liquid crystal layer is performed within a temperature range of about 90 ° to about 100 °, 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

<Comparative Example>

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 by Merck's MLC 6608 (Δn = 0.084, Δε = -4.3) 100% by weight. A cell gap of the liquid crystal layer of the liquid crystal display device was manufactured to 4.5 μm.

&Lt; 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 as a liquid crystal layer in which 97 wt% of MLC 6608 (Δn = 0.084, Δε = -4.3) of Merck and 3 wt% of KFLC 7 (Δn = 0.18) of Kingston Chemical were mixed at 100 ° C. The thickness of the liquid crystal layer of the said liquid crystal display device was produced in 4.5 micrometers. The 3 wt% KFLC 7 comprises 2.8 wt% non-chiral components and 0.2 wt% chiral components.

<Example 2>

The liquid crystal display device of Example 1 was manufactured in the same manner except for the liquid crystal layer material.

The liquid crystal layer was prepared as a liquid crystal layer obtained by mixing 95 wt% of MLC 6608 (Δn = 0.084, Δε = -4.3) of Merck and 5 wt% of KFLC 10 (Δn = 0.18) of Kingston Chemical. The 5 wt% KFLC 10 comprises 4.5 wt% non-chiral component and 0.5 wt% chiral component.

<Example 3>

The liquid crystal display device of Example 1 was manufactured in the same manner except for the liquid crystal layer material.

The liquid crystal layer was made of a liquid crystal layer in which 90 wt% of MLC 6608 (Δn = 0.084, Δε = -4.3) of Merck and 10 wt% of KFLC 3 (Δn = 0.18) of Kingston Chemical were mixed at 100 ° C. The 10 wt% KFLC 3 comprises 9.7 wt% of the non-chiral component and 0.3 wt% of the chiral component.

<Example 4>

The liquid crystal display device of Example 1 was manufactured in the same manner except for the liquid crystal layer material.

The liquid crystal layer was made of a liquid crystal layer in which 90 wt% of MLC 6608 (Δn = 0.084, Δε = -4.3) of Merck and 10 wt% of KFLC 10 (Δn = 0.18) of Kingston Chemical were mixed at 100 ° C. The 10 wt% KFLC 10 comprises 9.0 wt% of the non-chiral component and 1.0 wt% of the chiral component.

<Example 5>

The liquid crystal display device of Example 1 was manufactured in the same manner except for the liquid crystal layer material.

The liquid crystal layer was made of a liquid crystal layer obtained by mixing 85 wt% of MLC 6608 (Δn = 0.084, Δε = -4.3) of Merck and 15 wt% of KFLC 5 (Δn = 0.18) of Kingston Chemical. The 15 wt% KFLC 5 comprises 14.3 wt% non-chiral components and 0.7 wt% chiral components.

<Example 6>

The liquid crystal display device of Example 1 was manufactured in the same manner except for the liquid crystal layer material.

The liquid crystal layer was made of a liquid crystal layer obtained by mixing 80 wt% of MLC 6608 (Δn = 0.084, Δε = -4.3) of Merck and 20 wt% of KFLC 7 (Δn = 0.18) of Kingston Chemical at 100 ° C. The 20 wt% KFLC 7 comprises 18.6 wt% non-chiral components and 1.6 wt% chiral components.

&Lt; Example 7 >

The liquid crystal display device of Example 1 was manufactured in the same manner except for the liquid crystal layer material.

The liquid crystal layer was made of a liquid crystal layer in which 70 wt% of MLC 6608 (Δn = 0.084, Δε = -4.3) of Merck and 30 wt% of KFLC 3 (Δn = 0.18) of Kingston Chemical were mixed at 100 ° C. The 30 wt% KFLC 3 comprises 29.1 wt% of the non-chiral component and 0.9 wt% of the chiral component.

Comparative Examples and Examples 1 to 7 components and the thickness of the liquid crystal layer refer to Table 1 below.

Nematic liquid crystal Smectic liquid crystal Liquid crystal layer thickness Non-chiral ingredients Chiral ingredients Comparative Example 100 wt% 0 0 4.5 ㎛ Example 1 97 wt% 2.8 wt% 0.2 wt% 4.5 ㎛ Example 2 95 wt% 4.5 wt% 0.5 wt% 4.5 ㎛ Example 3 90 wt% 9.7 wt% 0.3 wt% 4.5 ㎛ Example 4 90 wt% 9.0 wt% 1.0 wt% 4.5 ㎛ Example 5 85 wt% 14.3 wt% 0.7 wt% 4.5 ㎛ Example 6 80 wt% 18.6 wt% 1.6 wt% 4.5 ㎛ Example 7 70 wt% 29.1 wt% 0.9 wt% 4.5 ㎛

Permeability evaluation

3 is a graph comparing the transmittance of the liquid crystal display of Comparative Example, Examples 1 to 7. 3 is a graph showing transmittance according to an applied voltage. The x-axis of FIG. 3 is an applied voltage and a unit is [V], and the y-axis shows transmittance.

Referring to FIG. 3, the transmittances of the liquid crystal displays of Examples 1 to 7 exhibit excellent overall transmittance as compared to the liquid crystal display of the comparative example. In more detail, it can be seen that in Example 1, although the effect is insignificant in terms of transmittance compared to the comparative example, the transmittance is improved. In addition, the liquid crystal display devices of Examples 2 to 6 exhibit a transmittance of about 1.8 to 2.0, and exhibit excellent transmittances compared to the liquid crystal display of the comparative example having a transmittance of about 1.5.

From the above evaluation, it is predicted that the non-chiral smectic liquid crystal in the liquid crystal layers of Examples 1 to 7 induces the liquid crystal molecules to be uniformly and stably aligned. Therefore, it can be seen that the transmittance of the liquid crystal display devices of Examples 1 to 7 is superior to that of the liquid crystal display device of the comparative example.

4A is a graph showing the transmittance of the liquid crystal display of Comparative Example, the transmittance according to the amount of non-chiral component in the liquid crystal layer of the liquid crystal display of Examples 1 to 7, and FIG. 4B is the transmittance of the liquid crystal display of Comparative Example; It is a graph showing the transmittance according to the amount of chiral components in the liquid crystal layer of the liquid crystal display devices of Examples 1 to 7. 4A and 4B, the x-axis represents the non-chiral component or the amount of the chiral component, the unit is [% by weight], and the y-axis represents the transmittance.

Referring to FIG. 4A, when the non-chiral component in the liquid crystal layer was about 10 wt%, the highest transmittance was shown. As the non-chiral component increased more than 10% by weight, the transmittance was slightly lower than that of the non-chiral component. However, only about 30% by weight of the non-chiral component showed lower permeability than the comparative example.

Referring to FIG. 4B, when the chiral component is present in the liquid crystal layer, it is somewhat irregular, but when the chiral component is present in the liquid crystal layer, the transmittance is higher than that without the chiral component. However, only when the chiral component is about 0.7% by weight showed a lower permeability than without the chiral component.

Response speed evaluation

FIG. 5A is a graph comparing the response speeds of the liquid crystal displays of Comparative Examples and Examples 1 to 7. FIG. In FIG. 5A, the x-axis represents an applied voltage and a unit is [V], and the y-axis represents a response speed and a unit is [ms].

Referring to FIG. 5A, it can be seen that the response speeds of the liquid crystal display devices of Examples 1 to 7 are slightly increased than the response speeds of the liquid crystal display devices of the comparative example. On the other hand, the response speed of the liquid crystal display including the liquid crystal layer of Example 4 is shown to be substantially similar to the comparative example. The increased response speed is expected to be lowered by changing the amount or type of nematic liquid crystals. Alternatively, the increased response speed is expected to be lowered by adding more reactive mesogen material to the liquid crystal layer.

5B is a graph illustrating the rising time and the polling time of the liquid crystal display of the comparative example, and the rising time and the polling time of the liquid crystal display of Examples 1 to 7 according to the amount of non-chiral component. The x-axis of Figure 5b represents the amount of non-chiral components, the unit is [% by weight], the y-axis represents time and the unit represents [ms].

When the desired transmittance of the liquid crystal display device is 100%, when the liquid crystal display device is turned on, it takes time to display the transmittance 100%. The rising time refers to a time at which 10% to 90% transmittance is exhibited after turning on the liquid crystal display. On the contrary, when the liquid crystal display is turned off, it takes time until the transmittance is 0%. The falling time refers to a time at which 90% to 10% transmittance is exhibited after the liquid crystal display is turned off. Response time is the sum of rising time and polling time.

The comparative example shows a rising time of about 50 ms and a polling time of about 60 ms, and the response speed was measured to be about 110 ms. Referring to the data of Examples 1 to 7, the rising time and the polling time are slightly increased compared to the comparative example, and as a result, the response speed tends to be slightly increased.

FIG. 5C is a graph illustrating a rising time of the liquid crystal display devices of Comparative Examples and Examples 1 to 7 according to the applied voltage, and FIG. 5D is a polling time of the liquid crystal display devices of Comparative Examples and Examples 7 to 7. It is a graph which shows according to the voltage to become. 5C and 5D, the x-axis represents the applied voltage, the unit is [V], the y-axis represents time, and the unit represents [ms].

Referring to FIG. 5C, it can be seen that the rising speed of the liquid crystal display devices of Examples 1 to 7 is slightly increased than the rising speed of the liquid crystal display device of the comparative example. On the other hand, the rising speed of the liquid crystal display including the liquid crystal layer of Example 4 is shown to be substantially similar to the comparative example.

Referring to FIG. 5D, it can be seen that the polling speed of the liquid crystal display devices of Examples 1 to 7 is slightly increased than the polling speed of the liquid crystal display device of the comparative example. On the other hand, the polling speed of the liquid crystal display device including the liquid crystal layers of Examples 4 and 5 is substantially similar to the comparative example.

It is expected that the slightly increased rising and falling rates can be lowered by changing the amount or type of nematic liquid crystal. Alternatively, the increased rising and falling rates are expected to be lowered by adding more reactive mesogen material to the liquid crystal layer.

texture ( texture ) evaluation

6A through 6H and 7A through 7H are textures of the liquid crystal display of Comparative Example and Embodiments 1 through 7.

6A to 6H illustrate a white image by rotating a cross polarizer after applying a voltage of 7 V to the liquid crystal display devices of Comparative Examples and Examples 1 to 7. FIG. Referring to FIG. 6A, a defect that looks black at the edges of the slit or the boundary of the slit is shown. 6B to 6H, it can be seen that the images are generally brighter than that of FIG. 6ADP. In addition, it can be seen that the images of FIGS. 6D-6F have eliminated not only the edge portions of the slit, but also the defect at the boundary of the slit.

7A to 7H are applied to the liquid crystal display devices of Comparative Examples, Examples 1 to 7, and after applying a voltage of 7V to rotate the cross-polarizing plate to obtain black images (black images). Comparing the images of FIGS. 7A and 7B, it can be seen that light leakage is alleviated in the image of FIG. 7B.

Looking at the above textures, it can be seen that in the case of the liquid crystal layer containing a smectic material, the alignment of 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. Can be.

8A and 8B are graphs showing transmittances according to distances of the textures of Comparative Examples and Examples 1 to 7. FIG. 8A and 8B evaluate at 256 (2 ⁸ ) gray levels, show gray near black as going to zero, and show the darkness of gray at levels from 0 to 255. FIG.

FIG. 8A shows the gray level of the texture of FIGS. 6A-6H, which are often seen near 150-230 of the gray level as white images. In FIG. 8A, the comparative example is seen a lot between gray levels of about 150 to 200, and it can be seen that the width of the peak is wide. Examples 1, 2, and 5 are seen a lot between gray levels about 180 to 200, and it can be seen that the peak width is narrower than the peak width of the comparative example. In addition, it can be seen that Examples 3 and 4 show much between about 190 and 230.

FIG. 8B shows the gray level of the texture of FIGS. 7A-7H, which are often seen between 0-50 of the gray level as black images. The comparative example shows two peaks at about 50 and about 130, respectively, and can be seen that the width of the peak is wide. Examples 1-5 show peaks at about 20, 60 and 150, but it can be seen that the peak at 20 is the highest and the width is somewhat narrow.

Referring to the graphs of FIGS. 8A and 8B, although the effective side is generally insignificant compared to the comparative example, it can be seen that the liquid crystal display of Examples 3 and 5 shows better gray levels than the comparative example. It can be seen that, in the case of the liquid crystal layer including the smectic 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.

9A and 9B are graphs showing transmittances according to distances of the textures of Comparative Examples and Examples 1 to 7. FIG.

FIG. 9A illustrates the transmittance that is changed according to the distance of the slit after cutting the textures of FIGS. 6A to 6H in one direction. Referring to FIG. 8A, it can be seen that the comparative example exhibits a transmittance of 120 around the slit, so that it appears blacker than the outer portion of the slit. Examples 3 and 4 exhibit a transmission of about 140. Accordingly, it can be seen that the transmittances of Examples 3 and 4 are higher than those of the slits around the slits.

FIG. 9B illustrates the transmittance that is changed according to the distance of the slit after cutting the textures of FIGS. 7A to 7H in one direction. Referring to FIG. 8B, a light leakage defect is shown by showing a transmittance of 80 around the slits of the comparative example. Around the slits of Examples 3 and 4, light leakage defects of 80 or less seem to have been somewhat resolved.

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 (16)

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, 1 to 50% by weight of an achiral smectic liquid crystal (achiral smectic liquid crystal); And an extra nematic 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,
And the nematic liquid crystal comprises a negative nematic liquid crystal having negative dielectric anisotropy. The method of claim 1,
And the nematic liquid crystal comprises a positive nematic liquid crystal having positive dielectric anisotropy. The method of claim 1,
The liquid crystal layer further comprises a chiral liquid crystal. The method of claim 7, wherein
The chiral liquid crystal is a liquid crystal display device occupies 0.01 to 10% by weight in the liquid crystal layer. The method of claim 1,
The liquid crystal layer further comprises a reactive mesogen material. 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 is 3 to 50% by weight smectic liquid crystal; And an extra nematic liquid crystal, wherein the smectic liquid crystal comprises: 70 to 97% by weight of a non-chiral smectic liquid crystal; And 3 to 30% by weight of a chiral smectic liquid crystal. The method of claim 10,
The liquid crystal layer further includes a chiral dopant. 12. The method of claim 11,
The chiral smectic liquid crystal has a higher spontaneous polarization characteristic than the chiral dopant. The method of claim 10,
And the nematic liquid crystal comprises a nematic liquid crystal having negative dielectric anisotropy. The method of claim 10,
And the nematic liquid crystal comprises a nematic liquid crystal having positive dielectric anisotropy. The method of claim 10,
The liquid crystal layer further comprises a reactive mesogen material. The method of claim 10,
Further comprising an alignment layer disposed adjacent to the liquid crystal layer,
The alignment layer includes a reactive mesogen material.

Images