KR20140129848A - Light Shutter Particle And Method Manufacturing The Same, And Reflective Type Display Device Using The Same - Google Patents

Abstract

The present invention provides a light shutter particle which includes: a transparent conductive particle composed of a first core, made of a transparent conductive material, and a first shell covering the first core; and a porous chromic particle composed of a second core, made of a transparent porous material, and a second shell covering the second core. The first shell and the second shell are made of an electrochromic material.

Description

TECHNICAL FIELD The present invention relates to an optical shutter particle, a method of manufacturing the same, and a reflective display device using the optical shutter particle.

The present invention relates to an optical shutter particle whose transparency is controlled according to a voltage application, a method of manufacturing the same, and a reflective display device having a low response time and a high contrast ratio.

BACKGROUND ART [0002] In recent years, popularized display devices mainly use liquid crystal or OLED (Organic Light Emitting Diode), and display images using electric light.

These display devices require additional power for emitting light in addition to signal power for displaying a screen in the form of a backlight device or a self-luminescent display, thereby increasing power consumption. In addition, since the brightness is required to use the display device due to a decrease in visibility in outdoor use, deterioration due to power consumption and heat generation of the device occurs.

A reflective display device has been proposed as a structure capable of improving this.

The reflection type display device uses various methods such as electrophoresis, electrowetting, and polymer dispersed liquid crystal display. However, such a reflective display device has a problem that the reaction time is very long and the reflectance is low when a color filter is applied to express color, so that it is difficult to recognize the screen.

Disclosure of Invention Technical Problem [8] The present invention aims at solving the problem of a slow reaction rate and a decrease in contrast ratio occurring in a color representation, which is a problem of a reflective display device.

According to an aspect of the present invention, there is provided a light emitting device comprising: a first core made of a transparent conductive material; transparent conductive particles formed of a first shell surrounding the first core; A second core made of a transparent porous material and a porous shell formed of a second shell surrounding the second core, wherein each of the first shell and the second shell provides an optical shutter particle composed of an electrochromic material.

Here, the thickness of the first shell is 2 to 5 nm, and the diameter of the transparent conductive particle is 5 to 100 nm.

The transparent conductive material may be one selected from the group consisting of ITO (Indium Tin Oxide), ATO (Antimony Tin Oxide), FTO (Fluorine Tin Oxide), and AZO (Aluminum Zinc Oxide).

On the other hand, the thickness of the second shell is 2 to 5 nm, and the diameter of the transparent conductive particle is 30 to 200 nm.

The transparent porous material may be a transparent inorganic material containing titanium oxide (TiO ₂ ), zinc oxide (ZnO), silica (SiO ₂ ), polyaniline, polyethylenedioxythiophene (PEDOT, Poly 3,4 -Ethylene Dioxy Thiophene), an inorganic-inorganic nano-composite or an inorganic-organic hybrid material.

On the other hand, each of the first and second shells is composed of an inorganic material selected from tungsten trioxide (WO ₃ ), nickel hydroxide (NiO _x H _y ), niobic acid (Nb ₂ O ₅ ), and molybdenum trioxide (MoO ₃ ) Electrochromic materials, and thiophene. A polymer comprising repeating units derived from Carbazole, Phenylene Vinylene, Acetylene, Aniline, Phenylene Diamine, and Pyrrole Monomer, , A conductive polymer material selected from Viologens Derivatives, Phenothiazine, and Tetrathio Ful Balenium.

On the other hand, the present invention provides a method of manufacturing a semiconductor device, comprising: preparing a first mass of a transparent conductive material; Preparing a second mass of transparent porous material; The transparent conductive material and the transparent porous material were mixed with N-benzyl-N'-phosphonoethyl-4,4'-bipyridinium chloride (N-Benzyl-N'-Phosphonoethyl) -4,4'-Bipyridinium Dichloride ) Is dissolved in an organic solvent to be dispersed in the organic solvent.

Here, the first core material may be one of ITO (Indium Tin Oxide), ATO (Antimony Tin Oxide), FTO (Fluorine Tin Oxide), and AZO (Aluminum Zinc Oxide), and the porous discoloring core material may be titanium oxide ₂ ), transparent inorganic materials including zinc oxide (ZnO), silica (SiO ₂ ), and organic polymer materials including polyaniline and polyethylenedioxythiophene (PEDOT) And an inorganic-inorganic nano-composite or an inorganic-organic hybrid material.

The ratio of the first mass to the second mass is 1: 1 to 1: 8.

The N-benzyl-N'-phosphonoethyl-4,4'-bipyridinium chloride (N-Benzyl-N'-Phosphonoethyl) -4,4'-Bipyridinium Dichloride Hydrochloric acid is added to Mono-Quaternized Benzyl Viologen and Diethyl-2-Bromoethyl Phosphonate, and 2-propanol is added. Is a crystal formed by dropwise addition.

According to another aspect of the present invention, there is provided a liquid crystal display comprising: a first substrate on which a thin film transistor is formed; A reflective plate formed on the thin film transistor; A pixel electrode connected to the thin film transistor, the pixel electrode being divided into pixel units and disposed on the reflective plate; A common electrode formed on the second substrate to face the first substrate and facing the pixel electrode; And an optical shutter layer disposed between the pixel electrode and the common electrode and including the optical shutter particles according to any one of claims 1 to 6.

The reflective plate may be formed of any one selected from the group consisting of titanium oxide (TiO ₂ ), magnesium oxide (MgO), zinc oxide (ZnO), aluminum oxide (Al ₂ O ₃ ), and white oxide containing calcium carbonic acid Feature.

In addition, the reflective plate may be formed of an anion selected from the group consisting of anthraquinone, dipyrrolopyrrole, isoindolinol, azopyridone, azopyrrolidone, diazodialylide, triarylmethane, phthalocyanine, quinophthalone, thioindigo, An organic pigment having a group, and a dye.

The optical shutter layer includes a film.

The optical shutter layer further includes a transparent or opaque state depending on whether a voltage is applied to the optical shutter layer by the pixel electrode and the common electrode.

Further, the optical shutter particles forming the optical shutter layer may be formed by combining a material having red, green, blue, cyan, magenta, and yellow colors, or a single It is characterized by the use of materials.

In the reflective display device according to the present invention, the reaction time is shortened by the optical shutter particle having the core shell structure, and the reflector reflecting the external light acts as a color filter to improve the contrast ratio. Therefore, it has a fast response speed, low power consumption, and a high contrast ratio even in the outdoors.

1 is a view illustrating a reflective display device having an optical shutter layer according to the present invention.

The optical shutter particles according to the present invention serve to transmit or block light according to whether a voltage is applied or not. The optical shutter particles are transparent conductive particles whose conductivity is high due to high conductivity and whose transparency changes according to the presence or absence of voltage application, and conductive particles having a low specific surface area and excellent transmittance of visible light. And contains small porous discoloration particles.

The optical shutter particles include a first core and a first shell surrounding the first core. At this time, the first core is made of a material having high conductivity and high transmittance in visible light. For example, ITO (Indium Tin Oxide), ATO (Antimony Tin Oxide), FTO (Fluorine Tin Oxide), and AZO (Aluminum Zinc Oxide).

The first shell surrounding the first core is formed of an electrochromic material. Examples of the first shell include tungsten trioxide (WO ₃ ), nickel hydroxide (NiO _x H _y ), niobium oxide (Nb ₂ O ₅ ), 3 Inorganic electrochromic materials such as molybdenum oxide (MoO ₃ ) and the like, and thiophene. A polymer containing repeating units derived from Carbazole, Phenylene Vinylene, Acetylene, Aniline, Phenylene Diamine, Pyrrole Monomer and the like Polymer, Viologens Derivatives, Phenothiazine, Tetrathio Ful Balenium and the like. In addition to the above-mentioned materials, it may contain a substance which is electrochromic and which has different transparency when voltage is applied and voltage is insufficient, and which does not interfere with light transmission.

The shape of the transparent conductive particle is spherical or amorphous. It is preferable that the diameter of the transparent conductive particle is 5 to 100 nm, and the thickness of the first shell layer surrounding the first core is 2 to 5 nm. The transparent conductive particles thus formed are opaque or transparent when voltage is not applied and are transparent or opaque when a voltage is applied to transmit or block light.

The porous discoloration particles include a second core and a second shell surrounding the second core. At this time, the second core is made of a material having a large specific surface area and a high transmittance in visible light. As an example of this, titanium oxide (TiO ₂ ), zinc oxide (ZnO), silica (SiO ₂ ) and the like are mainly used.

The second shell surrounding the second core is formed of an electrochromic material. Examples of the second shell include tungsten trioxide (WO ₃ ), nickel hydroxide (NiO _x H _y ), niobic acid (Nb ₂ O ₅ ) Inorganic electrochromic materials such as molybdenum (MoO ₃ ) and thiophene. A polymer containing repeating units derived from Carbazole, Phenylene Vinylene, Acetylene, Aniline, Phenylene Diamine, Pyrrole Monomer and the like Polymer, Viologens Derivatives, Phenothiazine, Tetrathio Ful Balenium and the like. In addition to the above-mentioned materials, it may contain a substance which is electrochromic and which has different transparency when voltage is applied and voltage is insufficient, and which does not interfere with light transmission.

The porous discoloration particles are spherical or amorphous in shape and preferably have a particle diameter of 10 to 200 nm and a thickness of the second shell layer surrounding the second core of 2 to 5 nm. The porous discoloration particles thus formed are opaque or transparent when the voltage is unfavorable, and are transparent or opaque when a voltage is applied, thereby transmitting or blocking light.

The transparent conductive particles formed of such a material and the porous inorganic colored discoloration particles are each formed of a core shell structure, and their composition ratios may be varied according to specifications required in a display panel.

- First Synthesis Example -

5 g of benzyl bromide and 5 g of 4,4-bipyridine were placed in 100 ml of dichloromethane to form the transparent conductive particles and the porous discoloration particles. Refluxing for a period of time to prepare the first solution.

Then, the same molar amount of 3-bromopropylamine hydrobromide is dissolved in acetonitrile, mixed with the first solution, and refluxed at 85 ° C for 6 hours. Subsequently, a small amount of ethyl acetate (Ethylacetate) is added dropwise to generate crystals, and the mixture is washed three times with methanol to prepare a mono-quaternized benzyl viologen. At this time, the mono-quaternized benzyl viologen has the following chemical formula 1.

- Formula 1-

4.4 g of Mono-Quaternized Benzyl Viologen and 15 g of Diethyl-2-Bromoethyl Phosphonate were added to water and refluxed at 40 ° C for 75 hours . Subsequently, 75 ml of 50% hydrochloric acid was added, refluxed for another 24 hours, and a small amount of 2-propanol was added dropwise thereto to obtain N-benzyl-N'-phosphonoethyl- , 4'-bipyridinium chloride (N-Benzyl-N'-Phosphonoethyl) -4,4'-Bipyridinium Dichloride) crystals (hereinafter referred to as first crystals). In this case, N-benzyl-N'-phosphonoethyl-4,4'-bipyridinium dichloride (ethylene N-benzyl-N'-Phosphonoethyl) .

- Formula 2-

0.5 g of the first crystal thus prepared, 5 g of ITO, and 5 g of TiO ₂ were placed in 100 g of methanol and dispersed using beads to prepare an optical shutter particle dispersion.

- Second Synthesis Example -

0.5 g of the first crystals formed according to the first synthesis example, 3.3 g of ITO and 6.6 g of TiO ₂ were added to 100 g of methanol and dispersed using beads to prepare an optical shutter particle dispersion.

- Third Synthesis Example -

0.5 g of the first crystal formed according to the first synthesis example, 2 g of ITO and 8 g of TiO ₂ were added to 100 g of methanol and dispersed using beads to prepare an optical shutter particle dispersion.

- Synthesis Example 4 -

0.5 g of the first crystals formed according to the first synthesis example, 1.1 g of ITO and 8.8 g of TiO ₂ were added to 100 g of methanol and beads were used to prepare an optical shutter particle dispersion.

- Comparative Example -

0.5 g of the first crystals formed according to the first synthesis example and 10 g of TiO ₂ were added to 100 g of methanol and dispersed using beads to prepare an optical shutter particle dispersion.

In order to measure the transmittance and the response time of the optical shutter particle dispersion prepared according to the first to fourth synthetic examples and comparative examples, ITO was deposited and then heated from room temperature to 200 ° C and then slowly cooled for 30 minutes The optical shutter particle dispersion prepared according to the first to fourth synthetic examples and comparative examples was spin-coated on each transparent substrate on a transparent substrate prepared to exhibit a 50 ohm surface resistance by annealing heat treatment, Thereby forming an optical shutter layer. At this time, the transparent substrate on which the optical shutter layer formed of the optical shutter particle dispersion according to each synthesis example is formed shows the opaque state of the optical shutter layer when voltage is applied, The ratio and the response time of the optical shutter layer are as shown in Table 1 below.

ITO: TiO ₂ ratio Transmittance Response time (ms) First synthetic example 1: 1 5% 400 Second synthetic example 1: 2 3.5% 800 Third synthetic example 1: 4 3% 1200 Example 4 1: 8 2% 1600 Comparative Example TiO ₂ 100% 1.7% 2000

As shown in Table 1, the transmittance of the optical shutter layer decreases as the ratio of TiO ₂ increases. In the comparative example composed of TiO ₂ alone, the ratio of transmitted light is only 1.7%, which means that the contrast ratio is increased. However, it can be seen that the response time is 2000 ms when the response time varies depending on the voltage application, and the response speed is higher than that of the first to fourth examples. On the other hand, in the case of the first synthetic example in which the ratio of TiO2 and ITO is the same, the response time is measured to be about 5 times smaller than that in the comparative example, but the ratio of light transmitted through the optical shutter layer blocking light is increased.

As a result, when the ratio of ITO is increased, the response time of the optical shutter layer is decreased but the blocking rate is lowered, and when the ratio of TiO 2 is increased, the response time of the optical shutter layer is increased but the blocking rate is increased. The reason why the ratio of ITO to TiO2 is limited to 1: 1 at the maximum in the production of the optical shutter particle dispersion is that when the ratio of the light passing through the optical shutter layer exceeds 5%, the back side of the optical shutter layer can be visually recognized The ratio of ITO to TiO2 of the present invention is preferably 1: 1 to 1: 8 in view of response time and image quality.

The details of the reflective display device having the optical shutter layer according to the first to fourth embodiments will be described in detail with reference to the drawings.

1 is a view showing a reflective display device having an optical shutter layer according to a synthesis example of the present invention.

1, a gate wiring 16, a data wiring 15, and a thin film transistor TR connected thereto are formed on an array substrate 10 of a reflective display device according to a synthesis example of the present invention do. A color reflector 20 is formed on the upper portion of the thin film transistor TR and a pixel electrode 22 is formed on the color reflector 20. Here, the color reflector 20 includes a separate reflector to exhibit a high reflectance. At this time, what can be used for the reflector is a material that can reflect white light by being incident on the reflective display device and is mainly made of titanium oxide (TiO 2), magnesium oxide (MgO), zinc oxide (ZnO) Al2O3), calcium carbonate, and the like can be used. In addition, the reflector can be changed to other materials as long as it has a high reflectance and reflects near-white reflected light as well as the above-mentioned materials. The color reflector 20 formed as described above may include a separate colorant to realize color. For example, an anthraquinone, dipyrrolopyrrole, isoindolinol, azopyridone, azopyrrolidone, diazodialylide, triarylmethane, phthalocyanine, quinophthalone, thioindigo, thiogenzene, Organic pigments, dyes and the like can be used for the colorant.

The pixel electrode 22 formed on the color reflector 20 is connected to the drain electrode 21 of the thin film transistor TR to apply a voltage to the light shutter layer 30. At this time, the drain electrode 21 and the pixel electrode 22 may be connected to each other by forming a contact hole in the color reflector 20. The optical shutter layer 30 receiving the voltage from the pixel electrode 22 includes the optical shutter particles synthesized according to the first through fourth embodiments, and the transparency is varied according to the amount of the applied voltage as described above. At this time, the transparent conductive particles 50 and the porous foliant particles 60 constituting the optical shutter layer 30 are transparent or opaque, and the basic or opaque color And when the optical shutter layer 30 can not achieve perfect black color, black can be realized by combining colored particles such as blue, yellow, magenta, red, green, and blue, respectively, . In addition, the optical shutter layer 30 may be formed in the form of a dispersion rather than a film, but it is preferable that the optical shutter layer 30 is formed in a film form when a liquid phase is formed, since normal screen driving may not be performed as particles move due to gravity Do.

A transparent substrate 40 is attached to the upper portion of the optical shutter layer 30. At this time, a black matrix (not shown) and a common electrode 35 for separating light of the color reflector 20 are formed on the transparent substrate 40. That is, the optical shutter layer 30 is positioned between the pixel electrode 22 and the common electrode 35, thereby applying a voltage to the optical shutter layer 30 to have transparency or opaque characteristics.

In the reflective display device having such a structure, the colorant is colored in the color reflector 20, and the colorant applied to the color reflector 20 and thus the transmittance and chromaticity of the reflective display device are described in detail .

- First Application Example -

In the reflective display device, CI Pigment Red 254 and a white pigment were mixed in a weight ratio of 1:30, and 3.5 g of the pigment dispersion in which they were dispersed was mixed with 12 g of an alkali-soluble resin and 7 g of a polyfunctional monomer (Dipentaerithritolexa acrylate) , 16.25 g of propylene glycol monomethyl acetate (PGMA), and 1 g of oxime-based compound, 1,2-octadione-1- (4-phenylthio) phenyl-2- (o-benzoyloxime) , CGI 124) was used as a photoinitiator to prepare a red photosensitive resin composition and applied to "red" pixels.

- Second application example -

In the reflective display device, CI Pigment Green 58 and a white pigment were mixed in a weight ratio of 1:30, and 3.5 g of the pigment dispersion in which they were dispersed, 12 g of an alkali-soluble resin and 7 g of a polyfunctional monomer (Dipentaerithritolexa acrylate) , 16.25 g of propylene glycol monomethyl acetate (PGMA), and 1 g of oxime-based compound, 1,2-octadione-1- (4-phenylthio) phenyl-2- (o-benzoyloxime) , CGI 124) was used as a photoinitiator to prepare a green photosensitive resin composition and applied to a "green" pixel.

- Third application example -

In the reflective display device, CI Pigment Blue 156 and white pigment were mixed in a weight ratio of 1:30, and 3.5 g of the pigment dispersion in which the CI pigment blue 156 and the white pigment were dispersed were mixed with 12 g of an alkali-soluble resin and 7 g of a polyfunctional monomer (Dipentaerithritolexa acrylate) , 16.25 g of propylene glycol monomethyl acetate (PGMA), and 1 g of oxime-based compound, 1,2-octadione-1- (4-phenylthio) phenyl-2- (o-benzoyloxime) , CGI 124) was used as a photoinitiator to prepare a blue photosensitive resin composition and applied to "blue" pixels.

- Fourth application example -

In the reflective display device, 3.5 g of the pigment dispersion in which the CI white pigment was dispersed, 12 g of the alkali-soluble resin and 7 g of the polyfunctional monomer (Dipentaerithritolexa acrylate) were mixed, and propylene glycol monomethyl acetate (PGMA) (Ciba-Geigy, CGI 124) was used as a photoinitiator to prepare a white photosensitive resin composition. And applied to "white" pixels.

As described above, it is preferable that the pigment dispersion is prepared according to the first to fourth application examples and applied to a color reflector so as to have a ratio of 15% of the pigment dispersion, and the results thereof will be described with reference to Table 2 below.

When voltage is applied When voltage is not applied x y Y _on x y Y _off First application example 0.45 0.31 35.4% 0.16 0.06 1.5% Example 2 0.31 0.33 70% 0.17 0.06 3.1% Example 3 0.18 0.22 26% 0.16 0.06 0.6% Example 4 0.31 0.33 75% 0.17 0.06 3%

In Table 2, x and y indicate coordinates based on the CIE chromaticity coordinates, and Y _on and Y _off indicate the ratio of light transmitted when the optical shutter layer is blocked or opened, respectively. Here, the color reflector colored with the colorant according to the first to fourth application examples has an average transmittance of 52% in a voltage applied state of pixels colored red, green, and blue, The color reflector in which the colorant according to the example is colored is measured with an average transmittance of about 2% in a voltage-unapplied state of pixels colored red, green, and blue. It can be seen that the transmissivity in the voltage applied state is about 25 times as much as the transmissivity in the voltage unaffected state, and the reflective display device according to the present invention can express a high contrast ratio.

The reflective display using the optical shutter particle of the core shell structure can be realized to exhibit a lower response time and a higher contrast ratio as compared with the conventional reflective display.

In addition, the material used for preparing the core-shell dispersion is not limited to the synthesis examples, and can be prepared using ITO and TiO ₂ as well as all materials capable of achieving the object of the present invention.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the present invention.

10: array substrate 15: gate wiring
16: Data line 20: Color reflector
21: drain electrode 22: pixel electrode
30: optical shutter layer 35: common electrode
40: transparent substrate 50: transparent conductive particle
60: porous discoloration particles

Claims (16)

A transparent conductive material; a first core made of a transparent conductive material; a transparent conductive particle formed of a first shell surrounding the first core;
A second core made of a transparent porous material and a second shell surrounding the second core,
Wherein each of the first and second shells comprises an electrochromic material.
The method according to claim 1,
Wherein the thickness of the first shell is 2 to 5 nm and the diameter of the transparent conductive particle is 5 to 100 nm.
The method according to claim 1,
Wherein the transparent conductive particles are selected from the group consisting of ITO (Indium Tin Oxide), ATO (Antimony Tin Oxide), FTO (Fluorine Tin Oxide), and AZO (Aluminum Zinc Oxide).
The method according to claim 1,
Wherein the thickness of the second shell is 2 to 5 nm and the diameter of the transparent conductive particle is 30 to 200 nm.
The method according to claim 1,
The porous discoloring particles may be transparent inorganic materials including titanium oxide (TiO ₂ ), zinc oxide (ZnO), silica (SiO ₂ ), polyaniline, polyethylenedioxythiophene (PEDOT, Dioxy Thiophene), an inorganic-inorganic nano-composite material or an inorganic-organic hybrid material.
The method according to claim 1,
Wherein each of the first and second shells comprises an inorganic electrochromic material selected from tungsten trioxide (WO ₃ ), nickel hydroxide (NiO _x H _y ), niobic acid (Nb ₂ O ₅ ), and molybdenum trioxide (MoO ₃ ) Substance, Thiophene. A polymer comprising repeating units derived from Carbazole, Phenylene Vinylene, Acetylene, Aniline, Phenylene Diamine, and Pyrrole Monomer, , A conductive polymer material selected from Viologens Derivatives, Phenothiazine, and Tetrathio Ful Balenium. The optical shutter particles according to claim 1,
Preparing a first mass of a transparent conductive material;
Preparing a second mass of transparent porous material;
The transparent conductive material and the transparent porous material were mixed with N-benzyl-N'-phosphonoethyl-4,4'-bipyridinium chloride (N-Benzyl-N'-Phosphonoethyl) -4,4'-Bipyridinium Dichloride ) Into the dissolved organic solvent to disperse the organic solvent
≪ / RTI >
8. The method of claim 7,
The transparent conductive material may be one of ITO (Indium Tin Oxide), ATO (Antimony Tin Oxide), FTO (Fluorine Tin Oxide), and AZO (Aluminum Zinc Oxide), and the transparent porous material may be titanium oxide (TiO ₂ ) A transparent inorganic material including zinc (ZnO), silica (SiO ₂ ), and an organic polymer material including an inorganic material such as polyaniline, polyethylenedioxythiophene (PEDOT) Nanocomposite or an inorganic-organic hybrid material.
8. The method of claim 7,
Wherein the ratio of the first mass to the second mass is 1: 1 to 1: 8.
8. The method of claim 7,
The above N-benzyl-N'-phosphonoethyl-4,4'-bipyridinium chloride (ethylene-4,4'-Bipyridinium Dichloride) Hydrochloric acid is added to Mono-Quaternized Benzyl Viologen and Diethyl-2-Bromoethyl Phosphonate, and 2-propanol is added dropwise thereto. Wherein the crystal is a crystal to be formed.
A first substrate on which a thin film transistor is formed;
A reflective plate formed on the thin film transistor;
A pixel electrode connected to the thin film transistor, the pixel electrode being divided into pixel units and disposed on the reflective plate;
A common electrode formed on the second substrate to face the first substrate and facing the pixel electrode;
And an optical shutter layer which is located between the pixel electrode and the common electrode and includes the optical shutter particles of any one of claims 1 to 6,
And the reflective display device.
12. The method of claim 11,
Wherein the reflection plate is made of a reflective type display device comprising a white acid oxide comprising at least one selected from titanium oxide (TiO ₂ ), magnesium oxide (MgO), zinc oxide (ZnO), aluminum oxide (Al ₂ O ₃ ), and calcium carbonic acid .
13. The method of claim 12,
The reflector may be formed of an anion selected from the group consisting of anthraquinone, dipyrrolopyrrole, isoindolinol, azopyridone, azopyrrolidone, diazodialylide, triarylmethane, phthalocyanine, quinophthalone, thioindigo, An organic pigment, and a dye.
12. The method of claim 11,
Wherein the optical shutter layer is formed of a film.
12. The method of claim 11,
Wherein the optical shutter layer is transparent or opaque depending on whether a voltage is applied to the optical shutter layer by the pixel electrode and the common electrode.
16. The method of claim 15,
The optical shutter particles forming the optical shutter layer may be formed of a single material that mixes red, green, blue, cyan, magenta, and yellow materials or changes to black to realize black when the opaque state is expressed in the pixel unit Wherein the reflective display device is a reflective display device.

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