KR101997930B1 - 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 facing away from 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 electrode and the liquid crystal layer, wherein 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.

Description

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

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

BACKGROUND ART [0002] Liquid crystal display devices are one of the most widely used flat panel display devices, and studies for high image quality, high brightness, and large size have been actively conducted. As a part of the study, the structure of the electrodes in the liquid crystal display device has been diversified and complicated for the purpose of high image quality, high brightness, and large size of the liquid crystal display device. When a driving voltage is applied to these electrodes, the liquid crystal molecules of the liquid crystal layer are changed in arrangement by an applied electric field, and the liquid crystal molecules are not uniformly arranged by the electrodes and are not stable. Uneven and unstable arrangement of the liquid crystal molecules causes a problem of lowering the luminance of the liquid crystal display device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device having improved brightness.

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 concept of the present invention provides a liquid crystal display device. The liquid crystal display device includes a first substrate; A second substrate facing away from 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 a nematic liquid crystal having negative dielectric anisotropy, a nematic liquid crystal having positive dielectric anisotropy, and a ferroelectric Liquid crystal.

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

According to another embodiment of the present invention, the liquid crystal display device 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 comprises 70 to 99.9% by weight of the nematic liquid crystal having the negative dielectric anisotropy and 0.1 weight% of the mixture of the nematic liquid crystal and the 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 positive dielectric anisotropy, the ferroelectric liquid crystal may include 10% by weight to 99% by weight.

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

According to another embodiment of the present invention, the liquid crystal layer comprises 0.1 to 30% by weight of a mixture of the nematic liquid crystal and the ferroelectric liquid crystal having positive dielectric anisotropy, 0.01 to 3% by weight of the reactive mesogenic material % And a nematic liquid crystal having an extra negative dielectric anisotropy.

Another embodiment according to the concept of the present invention provides a liquid crystal display device. The liquid crystal display device includes a first substrate; A second substrate facing away from 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 mesogenic material.

According to another embodiment of the present invention, the liquid crystal layer may comprise 0.1 to 30% by weight of the ferroelectric liquid crystal, 0.01 to 3% by weight of the reactive mesogen material and an excess of the negative dielectric anisotropy Nematic liquid crystals.

According to the embodiment of the present invention, the liquid crystal display device may include a nematic liquid crystal having negative dielectric anisotropy, a nematic liquid crystal having positive dielectric anisotropy, and a liquid crystal layer containing ferroelectric liquid crystal molecules. The alignment uniformity and stability of the liquid crystal molecules in the liquid crystal layer can be improved by the ferroelectric liquid crystal molecules of the liquid crystal layer, and the brightness of the liquid crystal display device can be improved.

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 for explaining a liquid crystal display according to an embodiment of the present invention.
2 is a cross-sectional view illustrating a liquid crystal display according to an embodiment of the present invention.
FIGS. 3A and 3B are graphs comparing transmittances 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 for 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.
5A to 5K are textures that change according to the voltage applied to the liquid crystal display device of the fifth embodiment.
6A to 6K are textures that change according to the 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 device]]

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

1 and 2, a liquid crystal display device 2 includes a first substrate 100, a second substrate 200 facing the first substrate 100, And a liquid crystal layer (300) formed between the second substrates (200). Since the first substrate 100 corresponds to a substrate on which thin film transistors are formed and is referred to as a thin film transistor substrate and the second substrate 200 corresponds to a substrate on which the 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 are formed on the first insulating substrate 101 in a first direction. 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 film interposed therebetween. The data lines include, for example, m + q data lines DL1, ..., DLm, DLm + 1, ..., DL (m + q) -1, DLm + q. Each of the pixels includes one of the gate lines GL1, ..., GLn, GLn + 1, ..., GL (n + p) -1, GLn + DLm, DLm + 1, ..., DL (m + q) -1, DLm + q.

Since each pixel PXL has the same structure, FIG. 1 shows an n-th gate line GLn, an m-th data line DLm, and a pixel PXL for convenience of explanation.

Each of the pixels 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 (CE). The thin film transistor includes a gate electrode GE, a gate insulating film 111, a semiconductor pattern SM, a source electrode SE, and a drain electrode DE.

The gate electrode GE protrudes from the nth gate line GLn or is provided on a partial area of the nth gate line GLn.

The gate electrode GE may be formed of a metal. The gate electrode GE may be formed of nickel, chromium, molybdenum, aluminum, titanium, copper, tungsten, or 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 nth gate line GLn and the nth gate line GLn.

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

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

The drain electrode DE is provided apart from the source electrode SE via the semiconductor pattern SM. The drain electrode DE is formed on the ohmic contact layer OC and a part of the drain electrode DE is provided so as to overlap with the gate electrode GE.

The source electrode SE and the drain electrode DE may be made of nickel, chromium, molybdenum, aluminum, titanium, copper, tungsten, or an alloy 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 spaced apart from each other on the semiconductor pattern SM. The 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 drain And becomes a channel portion CH forming 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 on a part of the drain electrode DE and directly on the gate insulating layer 111 to directly contact a part of the drain electrode DE with 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 through-hole without the same pattern as the opening.

The common electrode CE may include a pattern having an opening. According to an embodiment of the present invention, the common electrode CE may extend in one direction and have an equally spaced stripe structure. Although the common electrode CE having a stripe structure is exemplarily described in the present embodiment, the structure of the common electrode CE is not limited in the present invention.

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 orient liquid crystal molecules in the liquid crystal layer 300 in a pre-tilt direction. According to one embodiment, the first alignment layer 115 may be formed of a material selected from the group consisting of poly-amic acid, polyimide, lecithin, nylon, and PVA (polyvinylalcohol) And the like. According to 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 may be formed of a material selected from the group consisting of poly-amic acid, polyimide, lecithin, nylon, and PVA (polyvinylalcohol) And the like. According to another embodiment, the second alignment layer 215 may further include a reactive mesogen material.

The liquid crystal layer 300 may fill the space between the first and second substrates 100 and 200. According to one embodiment, the liquid crystal layer 300 may include a negative nematic liquid crystal having a negative dielectric anisotropy, a positive nematic liquid crystal and a ferroelectric liquid crystal having positive dielectric anisotropy, crystal. According to another embodiment, the liquid crystal layer 300 may include a non-ferroelectric liquid crystal and a ferroelectric liquid crystal. 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 of the FFS mode (field fringe switching mode) includes the ferroelectric liquid crystal, it is possible to make the alignment of the liquid crystal composition uniform and improve the stability of orientation have. Accordingly, the brightness of the liquid crystal display device including the liquid crystal layer 300 can be improved. Further, by further including a reactive mesogen material in the first and second alignment films 115 and 215, the alignment speed of the liquid crystal molecules in the liquid crystal layer 300 is increased, and the angle of orientation is increased, .

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

[ Liquid crystal layer _ 1st 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 one embodiment, the liquid crystal layer may comprise a nematic liquid crystal having a negative dielectric anisotropy of about 70 wt% to about 99.9 wt%. The liquid crystal layer may further comprise a mixture of nematic liquid crystal and ferroelectric liquid crystal having a dielectric anisotropy in an amount of about 0.1 wt% to about 30 wt%.

Wherein the mixture of nematic liquid crystal and ferroelectric liquid crystal having positive anisotropy comprises a nematic liquid crystal having a dielectric anisotropy in an amount of about 1 wt% to 90 wt% and a ferroelectric liquid crystal in an amount of about 10 wt% to about 99 wt% can do.

According to one embodiment, the ferroelectric liquid crystal in the liquid crystal layer may be in the range of about 0.01 wt% to about 29.7 wt%. 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 aligning property of the liquid crystal layer may be unstable. Further, 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 increases and the response time of the display device including the liquid crystal layer may be slowed down. Preferably, the ferroelectric liquid crystal may be about 10% by weight of the total amount of the liquid crystal layer.

In the following, exemplary materials of the nematic liquid crystal having negative dielectric anisotropy, nematic liquid crystal having positive dielectric anisotropy and ferroelectric liquid crystal will be described. With the exemplary materials described below, the nematic liquid crystal having the negative dielectric anisotropy of the present invention, the nematic liquid crystal having positive dielectric anisotropy, and the ferroelectric liquid crystal are not limited thereto.

First, the characteristics of a nematic liquid crystal are briefly described, and examples of a nematic liquid crystal having a negative dielectric anisotropy and a nematic liquid crystal having a positive dielectric anisotropy are categorized.

Nematic liquid crystals are liquid crystals in which liquid crystal molecules are irregular in position but their long axes are all directed in a certain direction. Since each molecule of the nematic liquid crystal can freely move in the major axis direction, it is easy to flow due to a small viscosity, and the direction of the nematic molecule is substantially equal to the up and down directions, so that polarization is canceled and generally does not exhibit ferroelectricity. In the direction perpendicular to the axial direction of molecules of the liquid crystal, physical properties are very different. Therefore, a nematic liquid crystal is a material having optical anisotropy. The difference between the dielectric anisotropy in which the axial direction is parallel and the dielectric anisotropy in which the axial direction is perpendicular is defined as a nematic liquid crystal having negative dielectric anisotropy when Δε is smaller than 0 and a nematic liquid crystal having positive dielectric anisotropy do.

Negative oilfield Anisotropy  Have Nematic  Liquid crystal

According to one 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 single. In another aspect, the nematic liquid crystal molecules having negative dielectric anisotropy may be different from each other. For example, the nematic liquid crystal molecules having negative dielectric anisotropy may include liquid crystal molecules having negative dielectric anisotropy having a first dielectric anisotropy and liquid crystal molecules having negative dielectric anisotropy having a second dielectric anisotropy. have. At this time, 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 and 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 by way of examples. The following materials may be used alone or in combination.

The nematic 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. The nematic liquid crystal having negative dielectric anisotropy may further include first base liquid crystal molecules.

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

Nematic liquid crystals having a negative dielectric anisotropy of a halogen-based bicyclic structure can be represented by the following general 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 replaced by CN, CF ₃ , or halogen, CH ₂ - group may be substituted with -CH═CH-, -O-, -CO-, -COO-, -OOC-, -O-OC-O- or -S-), X is independently of each other Halogenated alkyl, halogenated alkoxy, halogenated alkenyl or halogenated oxy having from 1 to 15 carbon atoms, and 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 can be represented by the following formulas (3) to (6).

(3)

Formula 4

Formula 5

6

In the formulas (3) to (6), R, L ¹ and L ² are as defined in the above formulas (1) and (2), L ³ and L ⁴ independently of one another are 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-.

Nematic liquid crystals having a negative dielectric anisotropy of a halogen-based tetra-cyclic structure can be represented by the following 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, R ² represents 1 to 15 carbon (In R ¹ and R ² , hydrogen may be replaced by CN, CF ₃ , or a halogen atom), or an alkyl, alkenyl, or alkoxy group having an atom , CH ₂ Group may be substituted by -O-, -S-, -C═C-, -CH═CH-, -OC-O- or -O-CO-), Z represents 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 a dielectric negative dielectric anisotropy has a side fluorinated indane derivative and can be represented by the following chemical formula (10).

10

In the above formula, m represents an integer, and n is 0 or 1.

Nematic liquid crystals having a dielectric anisotropy of negative cyanogen can be represented by the following formulas (11) to (13).

Formula 11

Formula 12

Formula 13

In Formulas 11 to 13, R ³ is an alkyl group having 1 to 15 carbon atoms, wherein hydrogen may be 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-), L ¹ and L ² independently of one another are 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-.

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

(a) a liquid crystal component comprising at least one compound having a dielectric anisotropy of less than -1.5 A:

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

(c) a chiral component C.

The liquid crystal component A may include at least one compound represented by the following general formulas (14) to (17).

Formula 14

Formula 15

Formula 16

Formula 17

The liquid crystal component B may include one or more compounds represented by the following general formulas (18) to (20). The liquid crystal component B may be the first base liquid crystal molecules described above.

18

Formula 19

20

In formulas 14 to 20, R < ⁴ > And R ⁵ are each independently selected from the group consisting of alkyl, alkoxy, alkoxy alkyl, alkenyl or alkenyl oxy having 1 to 15 carbon atoms, May be substituted by CN, CF ₃ , or a halogen atom, and the -CH ₂ - group may be replaced by -CH═CH-, -O-, -CO-, -COO-, -OOC-, -O- OC-O- or -S-), Y ¹ represents hydrogen or halogen.

As the chiral component C, a plurality of chiral dopants such as the following examples are available. The choice of dopant is not important in itself.

Positive heredity Anisotropy  Have Nematic  Liquid crystal

According to one embodiment, the nematic liquid crystal having positive dielectric anisotropy may comprise nematic liquid crystal molecules having positive dielectric anisotropy. In one aspect, the nematic liquid crystal molecules having positive dielectric anisotropy may be single. In another aspect, the nematic liquid crystal molecules having positive dielectric anisotropy may be different from each other. For example, the nematic liquid crystal molecules having positive dielectric anisotropy may include liquid crystal molecules having a positive dielectric anisotropy having a first dielectric anisotropy and liquid crystal molecules having positive dielectric anisotropy having a second dielectric anisotropy. have. At this time, 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 comprise nematic liquid crystal molecules having positive dielectric anisotropy and second base liquid crystal molecules. Each of the second basis liquid crystal molecules may include at least one selected from the group consisting of liquid crystal molecules having negative dielectric anisotropy and liquid crystal molecules having positive dielectric anisotropy and neutral liquid crystal molecules. In one aspect, the nematic liquid crystal having positive dielectric anisotropy may include nematic liquid crystal molecules having one kind of positive dielectric anisotropy, and second base molecules. In another aspect, the nematic liquid crystal having positive dielectric anisotropy may include liquid crystal molecules having various kinds of amounts of dielectric anisotropy and second base liquid crystal molecules.

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

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

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

The bimetallic nematic liquid crystal of bicyclic structure can be represented by the formula (21).

Formula 21

In formula (21), R ⁶ is an alkenyl having 1 to 15 carbon atoms, wherein hydrogen may be replaced by CN, CF ₃ , or halogen, and the -CH ₂ - group is -CH = Specific examples of the formula (21) are shown below. ≪ Desc / Clms Page number 13 >

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

A nematic liquid crystal having a positive dielectric anisotropy of a three-ring structure can be represented by the 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 one or more of the CH ₂ groups may be replaced by -O-, -S-, -C═C-, -CH═CH-, -OC -O- or -O-CO-, and L ¹ and L ² are each independently hydrogen or halogen.

A nematic liquid crystal having an isocyanate-based positive 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} and, wherein n is 1 to 15, A is

or

B is -CH ₂ -CH ₂ - or -C = C-, X ¹ is hydrogen or halogen, and m is 1, 2, 3, or 4. Specific examples of formula (23) are shown below.

The nematic liquid crystal having a halogen-based positive dielectric anisotropy may include a fluorine-based or chlorine-based material, and may have a single or multi-ring structure. Nematic liquid crystals having a fluorine-based positive dielectric anisotropy can be represented by the following formulas (24) to (27).

24

25

26

27

In Formulas 24 to 27, R ⁹ and R ¹⁰ are independently selected from the group consisting of alkyl having 1 to 15 carbon atoms, alkoxy, fluorinated alkyl, fluorinated alkoxy, alkenyl Alkenyloxy, alkoxyalkyl or fluorinated alkenyl, L ²¹ L ²² L ²³ and L ²⁴ are each independently of the other hydrogen or fluorine 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-.

A nematic liquid crystal having a positive dielectric anisotropy of a halogen-based bicyclic structure can be represented by the following formula (28).

28

In formula (28), R ¹¹ represents hydrogen, halogen, alkenyl having 1 to 15 carbon atoms, alkenyloxy, alkynyl or alkynoxy, and R ¹¹ , at least one -CH ₂ - group may be replaced by -O-, C═O or -S-, L ⁵ is halogen, a fluorinated alkyl of 1 to 15 carbon atoms, a 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 independently of each other (H) 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-. Specific examples of formula (28) are shown below.

In the above formula, n is 1 to 15.

Nematic liquid crystals having a positive dielectric anisotropy of a halogen-based tricyclic structure can be represented by the following 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 the alkyl or alkenyl is unsubstituted or at least monosubstituted by CN, CF ₃ , And one or more -CH ₂ - groups may be replaced 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.

Wherein R < ¹² > is as defined above.

A nematic liquid crystal having a positive dielectric anisotropy of a halogen-based four-ring structure can be represented by the following formulas (34) to (36).

(34)

(35)

Formula 36

In the formulas (34) to (36), R ¹³ is alkyl, alkoxy or alkenyl having 1 to 15 carbon atoms, wherein hydrogen in the alkyl, alkoxy or alkenyl 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 including a trisubstituted fluorine or a cyanation group can be represented by the formula (37).

37

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

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

The nematic liquid crystal having positive dielectric anisotropy may be a single substance or a mixture. A nematic liquid crystal mixture having positive dielectric anisotropy according to one embodiment,

a) a liquid crystal component A consisting of at least one compound having a dielectric anisotropy greater than +1.5,

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

c) optionally containing chiral component C,

The liquid crystal component A may comprise one or more compounds of the above formula (37). The liquid crystal component B may include at least one compound represented by the following formula (38). The liquid crystal component B may be the second base liquid crystal molecules described above.

Component C is a number of chiral dopants including cholesteryl nonanoate (CN), S-811, S-1011, S-2011 (Merck KGaA from Darmstadt, Germany) and CB15 (BDH of the material) can be used. The choice of dopant is not important in itself.

Formula 38

R ¹⁶ and R ¹⁷ is an alkyl group (alkyl), respectively and independently from each other the same or different, each is unsubstituted or substituted with CN, CF _3, or at least one substituted carbon atom of 15 or less with a halogen (halogen), Wherein one or more CH ₂ of these alkyl groups may be replaced by -O-, -S-, -C = C-, -CH = CH-, -OC-O- or -OCO-, The phenylene (1,4-phenylene) ring may be mono- or polysubstituted independently of each other by fluorine.

Ferroelectric liquid crystal

Ferroelectric liquid crystal is a kind of dielectric which is spontaneous polarization without electric field and is electrically insulated. However, unlike general dielectric, dielectric polarization is not proportional to the electric field, and the relationship between polarization and electric field And exhibits an ideality with an electric history. Ferroelectric liquid crystals not only have characteristic spontaneous polarization but also have a property that the spontaneous polarization is reversed by an electric field (polarization reversal).

According to one embodiment, the ferroelectric liquid crystal may include ferroelectric liquid crystal molecules. In one aspect, the ferroelectric liquid crystal molecules may be single. In another aspect, the ferroelectric liquid crystal molecules may be different 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. At this time, 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 basis liquid crystal molecules may include at least one selected from the group consisting of liquid crystal molecules having negative dielectric anisotropy and liquid crystal molecules having positive dielectric anisotropy and neutral liquid crystal molecules. In one aspect, the ferroelectric liquid crystal may include one kind 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, ferroelectric liquid crystals will be described by giving 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, (smetic chiral) ferroelectric liquid crystal, and the like. The ferroelectric liquid crystal may also be a banana-shaped ferroelectric liquid crystal. The ferroelectric liquid crystal may include a fluorine chiral end ferroelectric liquid crystal, a chiral allyl ester ferroelectric liquid crystal, a center core polyring chiral ferroelectric liquid crystal, a smetic chiral ferroelectric liquid crystal, Ferroelectric liquid crystals and banana-shaped ferroelectric liquid crystals can be used alone or in combination. In addition, the ferroelectric liquid crystal may further include third base liquid crystal molecules.

The fluorine-based chiral terminated ferroelectric liquid crystal may be represented by the following formula (39).

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, C and D are independently E is independently selected from the group consisting of a single bond, COO, OOC, and C = C (O), phenyl, mono-fluorophenyl, difluorophenyl, or cyclo- At least one of E is a single bond, q is 0 or 1, and R ¹⁸ is a terminal group of the following formula (40).

40

Wherein 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 from 1 to 15 linear or branched alkyl chain, J, M, W are each different, R ¹⁹ is alkenyl group comprising from 1 to 15 carbon atoms, (alkenyl), alkenyloxy (alkenyloxy), alkynyl (alkynyl ), Or alkynoxy.

The chiral aryl ester liquid crystal may be represented by the 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) -, Z is fluorine ) Or an alkyl group substituted with a halogen, and * represents a chiral carbon. Specific examples of Formula 41 include 4'-n-octyloxyphenyl 4 '- (1,1,1-trifluoro-2-octyloxycarbonyl) biphenyl-4- carboxylate octyloxyphenyl 4 '- (1,1,1-trifluoro-2-octyloxycarbonyl) biphenyl-4-carboxylate.

The core core polyring chiral ferroelectric liquid crystal can be represented by the following formulas (42) to (44).

Formula 42

(42) was synthesized in the same manner as in S-4- (trans-4-heptylcyclohexyl) -3'-chloro-4 "- (1-methylheptyloxy) chloro-4 "- (1-methylheptyloxy) terphenyl).

Formula 43

R-4-octyl-3 "-chloro-4 "-( 1-methylhexyloxy) -3 "-( 4-methylhexyloxy) ) quarterphenyl.

44

S-4-nonyl-3'-fluoro-4 '' - (2-chloropropyloxy) quaterphenyl (S-4-nonyl-3'-fluoro-4 ' ) quarterphenyl.

Formula 45

The compound of formula 45 is prepared by reacting butyl S-2- (4-octyl-2'-fluoro-3 "-trifluoromethyl-4 '2'-fluoro-3"-trifluoromethyl-4'''- quarterphenyloxy) -propionate).

The ferroelectric smectic liquid crystal may be represented by at least one of the following formulas (47) and (48).

Formula 47

48

In formulas (47) and (48), R ²⁰ and R ²¹ are each a linear alkyl group of 1 to 9 carbon atoms, and R ²² And R ²³ is in each identical or different C 1 -C 18 linear alkyl (alkyl), and (R ²⁰ to R ^23, hydrogen can be optionally substituted with CN, CF _3, or halogen (halogen) atom, -CH ₂ -Group may optionally be substituted by -CH = CH-, -O-, -CO-, -COO-, -OOC-, -O-OC-O- or -S-, X is hydrogen or halogen (halogen). Specific examples of the above formulas (47) and (48) are shown below.

The chiral smectic ferroelectric liquid crystal can be represented by the above formula (49).

Formula 49

In formula (49), R ²⁴ represents a chiral or achiral C 1 -C 20 alkyl or alkenyl, R ²⁵ represents a chiral or bicyclic C 1 -C 20 alkoxy (alkenyloxy), alkenyloxy, alkylcarbonyloxy, alkenylcarbonyloxy (alkenyl-COO-) (in R ²⁴ and R ²⁵ , hydrogen is CN , CF ₃ or a halogen atom, and the -CH ₂ - group may be replaced by -CH═CH-, -O-, -CO-, -COO-, -OOC-, -O-OC- 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- and L ¹⁰ to L ¹⁴ are hydrogen, halogen, cyano, nitro, alkyl of 1 to 20 carbon atoms or alkenyl ), and (-CH ₂ - groups may be replaced by -CH = CH-, -O-, -CO-, -COO-, -OOC-, -O-OC-O- , or -S-), X ⁹ is -CH- or quality A. A specific example of the above formula (49) is shown below.

The banana ferroelectric liquid crystal may be represented by the following general formula (50).

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 >

or

, 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 the above formula (50) are shown below.

The ferroelectric liquid crystal may be a ferroelectric liquid crystal single substance or a mixture containing a 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, an alkyl group having 1 to 20 carbon atoms, Alkenyl group wherein one or two -CH ₂ - groups can in each case be replaced by -O-, -C (= O) O- or -Si (CH ₃ ) ₂ - , At least one hydrogen of the alkyl or alkenyl group may be replaced by fluorine or CH ₃ ), and R ³² , R ³³ , R ³⁴ , and R ³⁵ are each CH ₃ .

As described above, in the liquid crystal layer according to the embodiment of the present invention, when an electric field is applied 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 . Since the ferroelectric liquid crystal of the liquid crystal layer has a large alignment property with respect to the molecules and an arrangement characteristic according to the electric field, the orientation of the liquid crystal layer can be uniform and stabilized.

According to an embodiment of the present invention, the liquid crystal layer may further include a reactive mesogenic material. Wherein the liquid crystal layer comprises a nematic liquid crystal having from about 0.01 wt% to about 3 wt% of a reactive mesogenic material and a negative dielectric anisotropy of from about 70 wt% to about 99.9 wt% To about 30% by weight of a nematic liquid crystal and a ferroelectric liquid crystal having a dielectric anisotropy, and a nematic liquid crystal having an extra negative dielectric anisotropy.

The reactive mesogenic material means a polymerizable mesogenic compound. A "mesogenic compound" or "mesogenic material" may include one or more rod-shaped, plate-like or disk-shaped mesogenic groups, i.e., materials or compounds containing groups with the ability to induce liquid crystalline phase behavior. The reactive mesogen material may be a material that is polymerized by light such as ultraviolet light and is oriented in accordance with the orientation state of the adjacent material.

An example of such a reactive mesogenic material is a compound represented by the following formula:

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

Here, 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-2,6-diyl, Z1 is one of COO-, OCO-, and a single bond, and n can be one of 0, 1, and 2.

More specifically, there can 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 this embodiment, since the liquid crystal layer includes the ferroelectric liquid crystal, alignment of the liquid crystal layer can be made uniform along with the nematic liquid crystal, and stability of orientation can be improved. Further, by including the reactive mesogen material in the liquid crystal layer, the orientation rate of the liquid crystal layer is increased, and the angle of orientation is increased, so that the optical characteristics can be improved.

[ Liquid crystal layer _ 2nd Example ]

The liquid crystal layer according to 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 account for 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 orientation of the liquid crystal layer may be unstable. In addition, when the ferroelectric liquid crystal exceeds about 30 wt% of the total amount of the liquid crystal layer, the viscosity of the liquid crystal layer increases and the response speed of the display device including the liquid crystal layer may be slowed down. Preferably, the ferroelectric liquid crystal may be about 10% by weight of the total amount of the liquid crystal layer.

According to an aspect, the liquid crystal layer may further include a reactive mesogenic material. In this case, the liquid crystal layer may comprise about 0.1% to about 30% by weight of the ferroelectric liquid crystal, about 0.01% to about 3% by weight of the reactive mesogenic material, and a nematic liquid crystal having extra negative dielectric anisotropy .

The components, structures and examples of the nematic liquid crystal, ferroelectric liquid crystal and reactive mesogen material having the negative anisotropy described in this embodiment are substantially the same as those described above, and 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 comprise a nematic liquid crystal having a negative dielectric anisotropy of about 70 wt% to about 99.9 wt%. The liquid crystal layer may further comprise a mixture of nematic liquid crystal and ferroelectric liquid crystal having a dielectric anisotropy in an amount of about 0.1 wt% to about 30 wt%.

Wherein the mixture of nematic liquid crystal and ferroelectric liquid crystal having positive anisotropy comprises a nematic liquid crystal having a dielectric anisotropy in an amount of about 1 wt% to 90 wt% and a ferroelectric liquid crystal in an amount of about 10 wt% to about 99 wt% can do.

According to an aspect, the liquid crystal layer may further include a reactive mesogenic material. In this case, the liquid crystal layer may comprise a mixture of nematic liquid crystal and ferroelectric liquid crystal having a dielectric anisotropy in an amount of about 0.1 wt% to about 30 wt%, about 0.01 wt% to 3 wt% of a reactive mesogenic material, And a nematic liquid crystal having extra negative anisotropy.

The components, structures and examples of negative anisotropic nematic liquid crystal, positive anisotropic nematic liquid crystal, ferroelectric liquid crystal, and reactive mesogenic material described in this embodiment are substantially the same as those described above, Description thereof will be omitted.

According to this embodiment, since the liquid crystal layer includes the ferroelectric liquid crystal, alignment of the liquid crystal layer can be made uniform along with the non-ferroelectric liquid crystal, and stability of alignment can be improved. Further, by including the reactive mesogen material in the liquid crystal layer, the orientation rate of the liquid crystal layer is increased, and the angle of orientation is increased, so that the optical characteristics can be improved.

Hereinafter, a method for 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 can be produced by mixing a nematic liquid crystal having negative anisotropy, a nematic liquid crystal having positive dielectric anisotropy, and a ferroelectric liquid crystal. Wherein the liquid crystal layer comprises a nematic liquid crystal having a negative dielectric anisotropy of about 70 wt% to about 99.9 wt%, a mixture of a nematic liquid crystal and a ferroelectric liquid crystal having a dielectric anisotropy in an amount of about 0.1 wt% to about 30 wt% . Wherein the mixture of nematic liquid crystals and ferroelectric liquid crystals having positive anisotropy comprises a nematic liquid crystal having a dielectric anisotropy in an amount of about 1% by weight to 90% by weight, and a mixture of about 10% to about 99% Liquid crystal.

According to an aspect, the liquid crystal layer may further include a reactive mesogenic material. In this case, the liquid crystal layer may contain a mixture of nematic liquid crystal and ferroelectric liquid crystal having a dielectric anisotropy of about 0.01 wt% to 3 wt% of a reactive mesogenic material and an amount of about 0.1 wt% to about 30 wt% And a nematic liquid crystal having a negative dielectric anisotropy of?

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

According to an aspect, the liquid crystal layer may further include a reactive mesogenic material. In this case, the liquid crystal layer may comprise about 0.01 wt.% To about 3 wt.% Of the reactive mesogenic material, the 0.1 wt.% To about 30 wt.% Of the ferroelectric liquid crystal and the nematic liquid crystal having extra negative dielectric anisotropy .

In the mixing process, the process temperature may be a temperature at which the largest amount of the liquid crystal layer exhibits isotropic characteristics. According to embodiments of the present invention, the mixing process temperature may be performed at a temperature ranging from about 90 ° C to about 100 ° C. The temperature range may be a temperature range when the nematic liquid crystal having negative dielectric anisotropy exhibits isotropic properties. In the present embodiment, the mixing of the liquid crystal layers is performed within a temperature range of about 90 캜 to about 100 캜, 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 >

1 and 2, including a first substrate including a common electrode having a stripe pattern and a pixel electrode of a through plate, a second substrate, and a liquid crystal layer filling between the first and second substrates, . The liquid crystal display device was fabricated in an FFS (field fringe switching) mode.

The liquid crystal layer was prepared from a liquid crystal composition obtained by mixing 90% by weight of MLC 6608 (DELTA n = 0.084, DELTA = = -4.3) and 10% by weight of KFLC 3 (DELTA n = 0.18) The thickness of the liquid crystal layer of the liquid crystal display device was 3.3 mu m.

≪ Examples 2 to 5 >

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

≪ Comparative Example 1 &

1 and 2, including a first substrate including a common electrode having a stripe pattern and a pixel electrode of a through plate, a second substrate, and a liquid crystal layer filling between the first and second substrates, . The liquid crystal display device was fabricated in an FFS (field fringe switching) mode.

The liquid crystal layer was made of 100 weight% of MLC 6608 (DELTA n = 0.084, DELTA epsilon = -4.3) of Merck. The thickness of the liquid crystal layer of the liquid crystal display device was 3.3 mu m.

≪ Comparative Examples 2 to 5 >

The liquid crystal display devices of Comparative Examples 2 to 5 were fabricated in the same manner as in Comparative Example 1 except for the thickness of the liquid crystal layer. The thicknesses of the liquid crystal layers of Comparative Examples 2 to 5 are shown in 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

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

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

As a result of the evaluation described above, the ferroelectric liquid crystal in the liquid crystal layer of each of Examples 1 to 5 leads the liquid crystal molecules to be able to align uniformly and stably, so that the transmittance of the liquid crystal display devices of Examples 1 to 5 is lower than that of Comparative Examples 1 to 5 And is superior to the transmittance of the liquid crystal display device.

Rate of response speed

4A and 4B are graphs for 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.

4A and 4B are graphs showing the response speed according to the applied voltage. In FIG. 4A and FIG. 4B, the x-axis is the applied voltage in units of [V] and the y-axis is the response speed in units of [ms].

Referring to FIGS. 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 the response speed of the liquid crystal display devices of Comparative Examples 1 to 5. Particularly, the larger the applied voltage, the less the difference in response speed occurred. Since the liquid crystal layers of Examples 1 to 5 contain the ferroelectric liquid crystal, the viscosity of the liquid crystal layer is increased and seems to be somewhat slower than the response speed of the liquid crystal display devices of Comparative Examples 1 to 5. 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 have stable and homogeneous alignment of liquid crystal molecules by including the ferroelectric liquid crystal, and the response speed can be maintained as usual.

texture ( texture ) evaluation

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

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

5D and 6D are textures to which a voltage of 3 V was applied to the liquid crystal display device of Example 5 and the liquid crystal display device of Comparative Example 5, respectively. In the texture of the liquid crystal display device of FIG. 6D, a white stripe is seen, but is not shown in the texture of the liquid crystal display of FIG. 5D. The above defects can also be seen in Fig. 6E.

In the case of the liquid crystal layer including the ferroelectric material, the orientation of the liquid crystal molecules in the liquid crystal layer is uniform and stable compared to the liquid crystal layer not including the 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 facing away from 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
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 nematic liquid crystal having negative dielectric anisotropy, a nematic liquid crystal having positive dielectric anisotropy, and a ferroelectric liquid crystal,
Wherein the liquid crystal layer comprises 70 wt% to 99.9 wt% of a nematic liquid crystal having negative dielectric anisotropy; And 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 according to claim 1,
Wherein the liquid crystal display device is a field fringe switching (FFS) mode. The method according to claim 1,
And an alignment layer disposed adjacent to the liquid crystal layer. The method of claim 3,
Wherein the alignment layer comprises a reactive mesogen material. delete The method according to claim 1,
Wherein in the mixture of the nematic liquid crystal and the ferroelectric liquid crystal having the positive dielectric anisotropy, the ferroelectric liquid crystal comprises 10% by weight to 99% by weight. The method according to claim 1,
Wherein the liquid crystal layer further comprises a reactive mesogenic material. 8. The method of claim 7,
The liquid-
0.1 wt% to 30 wt% of a mixture of the nematic liquid crystal and the ferroelectric liquid crystal having positive dielectric anisotropy;
0.01% to 3% by weight of said reactive mesogenic material; And
And a nematic liquid crystal having extra negative dielectric anisotropy. delete delete delete delete delete delete

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