KR101953024B1 - Liquid crystal display comprising High polarization and High color regenerative quantum rod film - Google Patents

Abstract

The present invention relates to a quantum rod film of polarized light and color reproducibility which can be used as a polarizing film and a color filter by aligning quantum rods in a predetermined direction and a method for manufacturing the same.
Since the quantum rod film of the present invention can emit linearly polarized light to a desired wavelength band, it can simultaneously perform a role of a color filter and a polarizing plate. That is, since the quantum rod film of the present invention emits light with different wavelengths, it can reduce the optical loss compared to the conventional color filter and can also function as a polarizing film because it emits linearly polarized light in the long axis direction. Therefore, when the quantum rod film of the present invention is applied to a liquid crystal display device, the light efficiency and color reproducibility can be increased, and power consumption can be greatly reduced.
In addition, since the quantum rod film of the present invention can replace the color filter and the polarizing film at the same time, a thin and light liquid crystal display device can be innovatively manufactured.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device including a quantum-rod film having polarization and color reproducibility,

The present invention relates to a quantum rod film with polarization and color reproducibility and a manufacturing method thereof, and more particularly to a quantum rod film with polarized light and color reproducibility which can be used as a polarizing film and a color filter by aligning quantum rods in a predetermined direction, And a manufacturing method thereof.

A liquid crystal display (LCD) is a non-active light emitting display that requires a separate backlight device for displaying a color image. When a color image is displayed, a red, green, Respectively.

The red, green, and blue color filters pass only light of a specific wavelength corresponding to each color among the white light incident from the backlight device. Therefore, in the liquid crystal display device, there is light loss due to the color filter, and approximately two-thirds of the incident light is lost.

A polarizing film of a liquid crystal display device is a basic component because it has a light switching function and is a mechanism having a light transmission and shielding function. However, the polarizing film absorbs light in a specific direction and shields it, thereby causing light loss like a color filter.

As described above, most of light is lost in a color filter and a polarizing plate, resulting in high power consumption.

The present invention provides a film capable of solving the high power consumption problem of a liquid crystal display element.

The present invention provides a film capable of improving the light efficiency and color reproducibility of a liquid crystal display element.

The present invention, in one aspect,

Applying a quantum rod composition comprising a quantum rod and a polymerizable liquid crystal mixture on a substrate;

Drying;

Providing an electric or magnetic field to the substrate coated with the quantum rod composition to align the quantum rod in a predetermined direction; And

Heat or light to cure the quantum rod composition. ≪ Desc / Clms Page number 2 >

Yet another aspect of the present invention is

Forming electrodes on the substrate at predetermined intervals;

Coating a sacrificial layer on the substrate and the electrode;

Applying a quantum rod composition layer in which a quantum rod and a polymerizable liquid crystal mixture are mixed on the sacrificial layer;

Drying;

A step of aligning the crocheting rod in a predetermined direction by applying power to the electrode

Irradiating heat or light to cure the quantum rod composition layer into a film; And

And separating the film from the substrate by removing the sacrificial layer.

In another aspect,

A cured photoreactive liquid crystal compound film; And

A plurality of quantum rods immersed and dispersed in the film and aligned in a predetermined direction,

The photoreactive liquid crystal compound film is formed by UV polymerization of a photoreactive mesogen (RM) and a polymer monomer used as a solvent thereof,

Wherein the photoreactive mesogens (RM) are positioned in the same direction as the quantum rods between the quantum rods,

Wherein the quantum rod film provides emission spectra of different wavelength ranges depending on the type and size of the quantum rod,

The quantum rod film is related to a quantum rod film that emits linearly polarized light in the long axis (length) direction of the quantum rod.

In yet another aspect,

 A liquid crystal layer; And

And a color filter disposed on the liquid crystal layer,

Wherein the color filter is a liquid crystal display element comprising first to third quantum rod films emitting red, green or blue light,

Wherein the quantum rod film is a quantum rod film,

Wherein the quantum-rod film is used as a polarizing film that emits linearly polarized light.

Since the quantum rod film of the present invention can emit linearly polarized light to a desired wavelength band, it can simultaneously perform a role of a color filter and a polarizing plate. That is, since the quantum rod film of the present invention emits light with different wavelengths, it can reduce the optical loss compared to the conventional color filter and can also function as a polarizing film because it emits linearly polarized light in the long axis direction. Therefore, when the quantum rod film of the present invention is applied to a liquid crystal display device, the light efficiency and color reproducibility can be increased, and power consumption can be greatly reduced.

In addition, since the quantum rod film of the present invention can replace the color filter and the polarizing film at the same time, a thin and light liquid crystal display device can be innovatively manufactured.

FIG. 1 is a schematic diagram for manufacturing a quantum rod film according to a first embodiment of the present invention. FIG.
2 is a schematic view of an electric field generating device according to a first embodiment of the present invention when the substrate is in the form of a sheet.
FIG. 3 is a schematic view of an electric field generating apparatus according to the first embodiment when the substrate coating method is a roll-to-roll type.
FIG. 4 is a diagram showing an electric field distribution generated when alternating voltages are applied in the electric field generating device shown in FIG. 2. FIG.
5 is a schematic view showing the entire process of the quantum rod film according to the first embodiment.
Figure 6 is a schematic diagram of a quantum rod film according to a second embodiment of the present invention.
Figure 7 shows a schematic view of a quantum rod film produced by an embodiment of the present invention.
8 and 9 are schematic views in which a quantum rod film produced in the present invention is mounted on a liquid crystal display element.
10 shows a PL spectra, an absorption spectrum and a TEM image of the quantum rod used in Example 1. Fig.
Fig. 11 shows a polarized photoluminescence spectra of the quantum rod film prepared in Example 1. Fig.
12 shows the normal state of the quantum rod film prepared in Example 1 and the image under UV light.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein and the experimental methods described below are well known and commonly used in the art.

2 is a schematic view of an electric field generating device according to a first embodiment of the present invention when the substrate is in the shape of a sheet, FIG. 2 is a schematic view of the electric field generating device according to the first embodiment of the present invention, 3 is a schematic view of the electric field generator according to the first embodiment when the substrate coating method is a Roll to Roll type, FIG. 4 is an electric field distribution diagram generated when alternately applying a voltage in the electric field generator as shown in FIG. 2, Fig. 3 is a general schematic view of the process of the quantum rod film according to the first embodiment. Fig.

Referring to Figs. 1 to 5, the method for producing a quantum rod film of the present invention includes a composition application step, a quantum rod alignment step, and a curing step.

The present invention first applies a quantum rod composition in which a quantum rod and a polymerizable liquid crystal mixture are mixed on a substrate.

The polymerizable liquid crystal mixture may be a mixture of photoreactive mesogens in a solvent. The photoreactive mesogen is a liquid crystalline monomer having a group capable of polymerization by irradiation with heat or ultraviolet rays. Unlike a liquid crystal in which the phase varies according to temperature, the photoreactive mesogens are once polymerized to become a solid phase Refers to a substance that is no longer subject to change and is primarily used in optical films. For example, the liquid crystalline monomer having a polymerizable group includes a liquid crystal phase, including a mesogen group capable of exhibiting liquid crystallinity and a terminal group capable of photopolymerization, and is a monomer molecule capable of being photopolymerized by a photoinitiator . As the mesogens, calamitic mesogens expressing a nematic liquid crystal phase or discotic mesogens in the form of a plate capable of expressing a discotic liquid crystal phase can be used. As the polymerizable terminal group, an acrylic group, methacrylic group, vinyl ether group or epoxide group which is generally easy to radical polymerization can be used. The liquid crystalline monomer may be used in combination with two or more polymerizable functional groups, for example, one polymerizable mesogenic compound having a reactive group and / or a non-polar polar compound, to increase cross-linking of the polymer, Alignment profiles may be changed by changing their composition ratios.

As the polymerizable liquid crystal mixture, RMS03-013C of Merck Co., Ltd., in which a known reactive mesogen is dissolved in PGMEA (propyl glycol monomethyl ether acetate), may be used.

The polymerizable liquid crystal mixture may comprise a photoinitiator. As the photoinitiator, trimethylopropane triacrylate or the like may be used.

The polymerizable liquid crystal mixture may be a polymer that is cured by heat or ultraviolet light, or may further include monomers thereof. More specifically, the polymerizable material is selected from the group consisting of triacetyl cellulose (TAC), polyacryl group, polyolefin (PO), polycarbonate (PC), polyethylene terephthalate (PET) ), Polypropylene (PP), polyethylene (PE), and monomers thereof.

The quantum rod includes a core and a shell surrounding the core. The quantum rod (quantum rod) has a short axis length of 10 nm or less and is in a range showing a quantum size effect, but the quantum size effect does not appear because the length of the major axis is several tens of nm or more. When the quantum rod is irradiated with UV light, visible light of a specific wavelength is emitted from the quantum rod, and the emitted visible light is linearly polarized in the quantum rod horizontal length direction (long axis direction). The wavelength of the visible light emitted according to the size of the core can be adjusted.

The quantum rod may have an aspect ratio (major axis length / minor axis length) of 2 to 100.

The quantum rod may have a major axis length of 10 to 100 nm, preferably 20 to 80 nm, more preferably 30 to 50 nm.

The quantum rod may comprise a II-VI semiconductor material, a III-V semiconductor material, or a VI-IV semiconductor material. For example, the quantum rod may be made of any one or a mixture of two or more of CdSe, CdS, CdTe, ZnO, ZnSe, ZnS, ZnTe, HgSe, HgTe, CdZnSe, ZnO (II- PbTe, PbTe, PbTe, and PbTe, which are made of any one or a mixture of two or more of InN, GaN, InSb, InAsP, InGaAs, GaAs, GaP, GaSb, AlP, AlN, AlAs, AlSb, CdSeTe, ZnCdSe PbS, PbSnTe, Tl2SnTe5 (VI-IV group semiconductor material), or a mixture of two or more thereof.

The quantum rod emitting red light includes CdSe rod, CdSe / ZnS rod, InP rod, CdSe / CdS rod, ZnSe / CdS rod. The quantum rod emitting green light includes a CdSe rod, a CdSe / ZnS rod, and the like. ZnSe, ZnS, and ZnSe / ZnS rods are examples of quantum rods that emit blue light.

The method may comprise adding a quantum rod solution to the polymerizable liquid crystal mixture to produce the quantum rod composition. The method can include after the quantum rod solution (e. G., Toluene) with stirring the quantum rod composition.

The quantum rod solution can be prepared by mixing the quantum rod with a solvent (e.g., toluene).

The quantum rod is 0.1 to 1% by weight, preferably 0.1 to 0.5% by weight, based on the polymerizable liquid crystal mixture. And more preferably in the range of 0.1 to 0.2% by weight.

The solvent of the quantum rod solution is removed during the drying step. The drying step is carried out at a boiling point of the quantum-rod solvent above the boiling point of the solvent of the polymerizable liquid-crystal mixture.

Referring to FIG. 5, the present invention includes a step of aligning the quantum rod in a predetermined direction by providing an electric field or a magnetic field to a substrate coated with the quantum rod composition.

As shown in Fig. 1, a horizontal electric field can be applied to the composition by providing an electric field generating device 5 on the substrate 1 on which the quantum rod composition 2 is applied. At this time, the quantum rod and the polymerizable liquid crystal material (reactive mesogen) can be aligned in a certain direction by the horizontal electric field.

The electric field applied to the composition may have different values depending on the kind of the quantum rod, the content, and the kind of the polymerizable substance.

2 is a schematic view of an electric field generating device according to a first embodiment of the present invention when the substrate is in the form of a sheet. As shown in FIGS. 2 and 3, the horizontal electric field 6 generated by alternately applying a voltage to the electric field generating device is uniformly distributed over the entire area on the substrate coated with the composition located under the electric field generating device, .

The device 5 for generating an electric field or a magnetic field may be located above or below the substrate.

As shown in FIG. 4, the polarizing film manufacturing method according to the present invention can be applied to a roll-to-roll process. In this case, the substrate can be in the form of a long film. A long film form means a continuous film having a constant width and means a continuous film which can be fed in a roll-wound form. In the case of the roll-to-roll process, since the film moves continuously, it can be seen that a constant electric field or a magnetic field is applied to the entire film irrespective of the position of the electrode.

Since the horizontal electric field applied is a force field formed by the distribution and movement of (+) and (-) charges, there is a difference in properties of the flux that determines the direction and field intensity. Although embodiments and drawings of the present invention have been described mainly in terms of electric fields, application of the electric field and the description of the electric field to the magnetic field, as the electric field and the magnetic field are generated in the directions orthogonal to each other and have similar properties, It will be apparent to those skilled in the art that the orientation direction of the magnetic field is orthogonal to the electric field.

5, the present invention includes a curing step. The curing step is a step of curing the polymerizable material by providing heat or light to the mixture. By the curing step, the polymeric material is cured while polymer polymerization takes place. The polymeric material is cured to form a binder of the film, and the quantum rod is fixed by the binder and remains aligned.

The present invention comprises separating the cured quantum rod film from the substrate.

Fig. 6 is a schematic view of a second embodiment of producing the quantum rod film of the present invention. Referring to FIG. 6, the quantum rod film of the present invention

Forming electrodes (3) on the substrate (4) at predetermined intervals;

Coating a sacrificial layer (7) on the substrate and the electrode;

Applying a quantum rod composition layer (2) on which a quantum rod and a polymerizable material are mixed on the sacrificial layer;

Drying;

Applying power to the electrode to align the quantum rod in a predetermined direction

Irradiating heat or light to cure the quantum rod composition layer into a film; And

And removing the sacrificial layer to separate the film from the substrate.

In the second embodiment, the sacrificial layer 7 and the quantum rod composition layer 2 are applied to the electrode generator 5. The electrode generator is energized to align the quantum rods and then cure the composition layer. The present invention can remove the sacrificial layer (7) and separate the quantum-film film from the electrode-generating device (5).

PMMA (polymethylmethacrylate) may be used as the sacrificial layer, and PMMA may be removed with an organic solvent such as acetone or toluene.

The quantum rod composition and the electrode generator of the second embodiment can refer to the first embodiment described above.

7 is a schematic view of the quantum rod film produced in the present invention. 7, the quantum rod film of the present invention includes a binder 10, a quantum rod 20, and a photoreactive liquid crystal compound 30,

The binder 10 is formed by curing or polymerizing the above-mentioned curable polymer or its monomer.

The quantum rod 20 can be referred to above. In other words, the quantum rod may be a CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, GaAs, GaP, GaAs, GaSb, HgS, HgSe, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, AlSb, Cu2S, Cu2Se, CuInS2, CuInSe2, Cu2 (ZnSn) S4, and Cu2 (InGa) S4.

The quantum rod film can provide emission spectra of different wavelength ranges depending on the type and size of the quantum rod. For example, the quantum rod emitting red light includes a CdSe rod, a CdSe / ZnS rod, an InP rod, a CdSe / CdS rod, and a ZnSe / CdS rod. The quantum rod emitting green light includes a CdSe rod, a CdSe / ZnS rod, and the like. ZnSe, ZnS, and ZnSe / ZnS rods are examples of quantum rods that emit blue light.

The length of the major axis of the quantum rod is 10 to 100 nm, preferably 20 to 80 nm, more preferably 30 to 50 nm, and the length of the minor axis (diameter) is 1 to 10 nm. The emission wavelength band can be controlled by adjusting the length.

The quantum rod film emits linearly polarized light in the long axis (length) direction of the quantum rod. That is, when the quantum rod is irradiated with UV light, visible light of a specific wavelength is emitted from the quantum rod, and the emitted visible light is linearly polarized in the quantum rod horizontal length direction (long axis direction).

As described above, since the quantum rod film of the present invention can emit linearly polarized light to a specific wavelength band, it can simultaneously perform the role of a color filter and a polarizing plate. That is, since the quantum rod film of the present invention emits the light absorbed light at different wavelengths, the light loss can be reduced as compared with the conventional color filter.

8 and 9 are schematic views in which a quantum rod film manufactured according to the present invention is mounted on a liquid crystal display device. 8 and 9, the liquid crystal display element of the present invention includes a liquid crystal layer 110 and a color filter 120.

The color filter 120 may be formed of first to third quantum rod films emitting red, green or blue light.

The quantum rod film uses the above-described quantum rod film.

Since the quantum rod film emits linearly polarized light, it can replace the polarizer.

As described above, since the quantum rod film of the present invention can replace the color filter and the polarizing film at the same time, a thin and lightweight liquid crystal display device can be innovatively manufactured.

Hereinafter, the present invention will be described in detail with reference to the embodiments and drawings. It should be understood, however, that the appended claims are illustrative of the specific embodiments of the invention and are not intended to limit the scope of the invention.

Example  One

RMS solution (dissolved in PGMEA solvent, purchased from Merck, RMS03-013C, weight 100 mg) was prepared. A 3 mg CdSe quantum rod was placed in 300 μL toluene to prepare a CdSe colloid solution.

Twenty microliters of the CdSe quantum rod colloidal solution was added to 100 mg of the RMS solution prepared above, and the toluene was evaporated by slow stirring. The CdSe quantum rod was maintained at 0.1 to 0.2 wt% in the RMS solution. 10 [mu] L of the mixture was coated on the substrate and dried at 40 [deg.] C. After the electric field generator 5 was placed on the substrate, power was applied, and ultraviolet rays (25 mW / cm 2) were irradiated for about 2 minutes and UV cured.

10 shows a PL spectra, an absorption spectrum and a TEM image of the quantum rod used in Example 1. Fig. Referring to FIG. 10, the CdSe quantum rod absorbs light in a wavelength range of 300 nm to 500 nm and emits light in a wavelength range of 600 to 680 nm.

Fig. 11 shows a polarized photoluminescence spectra of the quantum rod film prepared in Example 1. Fig. (In black) and perpendicular (in red) to the analyzer (polarizer) and the quantum rod film (long axis direction of the quantum rod) located at the bottom (or top) of the quantum rod film And the emission intensity at the time of the comparison. As shown in FIG. 11, the luminescent intensity of the quantum rod is higher than that of the case where the longitudinal axis direction of the quantum rod and the analyzer (polarizing plate) are parallel to each other. As shown in Fig.

12 is a graph showing the normal state of the quantum rod film prepared in Example 1 and the image under UV light.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

1: substrate 2: quantum rod composition
3: Electrode 4: Electric field generating device substrate
5: electric field generating device 6: electric field
7: sacrificial layer
10: binder 20: quantum rod
30: liquid crystal compound

Claims (11)

delete delete delete delete delete delete delete A liquid crystal layer; And
And a quantum-rod color filter disposed on the liquid crystal layer,
Wherein the quantum rod color filter is a first to a third quantum rod film in which a first quantum rod for emitting red light, a second quantum rod for emitting green light, and a third quantum rod for emitting blue light are repeatedly formed for each pixel,
Wherein the first quantum rod film comprises a cured photoreactive liquid crystal compound film and the first quantum rod immersed and fixed in dispersion in the liquid crystal compound film and aligned in a predetermined direction, And a second quantum rod immersed and dispersed in the liquid crystal compound film and aligned in a predetermined direction, and the third quantum rod film comprises a cured photoreactive liquid crystal compound film and the liquid crystal compound film And the third quantum rod being dispersed and fixed in a predetermined direction,
The photoreactive liquid crystal compound film is formed by UV curing a polymerizable liquid crystal mixture comprising a photoreactive mesogen (RM) and a polymer monomer used as a solvent thereof, and the polymer monomer dissolves the photoreactive mesogen (RM) The polymerization can be carried out while it is possible,
Wherein the first quantum rod to the third quantum rod are contained in the range of 0.1 to 0.5 wt% relative to the polymerizable liquid crystal mixture,
Wherein the photoreactive mesogens (RM) are aligned in the same direction as the first quantum rod to the third quantum rod between the first quantum rod and the third quantum rod. 9. The method of claim 8, wherein the quantum rod comprises at least one of Cds, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, GaAs, GaP, GaAs, GaSb, HgS, HgSe, HgSe, HgTe, InAs, InP, InSb, Wherein the liquid crystal display element is at least one of AlSb, Cu2S, Cu2Se, CuInS2, CuInSe2, Cu2 (ZnSn) S4, and Cu2 (InGa) S4. The liquid crystal display element according to claim 8, wherein the polymeric monomer is PGMEA (propylglycol monomethyl ether acetate).

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