Reflective photonic crystal ink, and electrophoretic device and home appliance comprising same

Abstract

The reflective photonic crystal ink according to an embodiment comprises: nanoparticles; and a dispersion solvent in which the nanoparticles are dispersed, wherein the dispersion solvent may comprise a phenylalkylamine (PAA)-based material.

Description

Reflective photonic crystal ink and electrophoretic devices and home appliances containing the same

[0001] The present invention relates to a reflective photonic crystal ink and an electrophoretic device and home appliance including the same.

[0002] Electrophoresis is a phenomenon in which a substance with an electric charge in a solution moves within an electric field, and electrophoretic ink is an ink that can be displayed using the electrophoretic phenomenon.

[0003] Electrophoretic ink, also known as reflective photonic crystal ink, does not emit light on its own like a light-emitting diode. Instead, it reflects incoming light through the arrangement of particles within the ink, enabling display. Display devices manufactured using this electrophoretic ink are less expensive to manufacture than conventional light-emitting devices like EL, LCD, and LED, and thus have potential applications in a variety of fields.

[0004] Meanwhile, electrophoretic ink requires surface treatment or dispersion stabilizers on the particle surface to mix the nanoparticles with the solvent. This increases the number of processes, potentially reducing yield or increasing manufacturing costs. Furthermore, if an electric field is continuously applied to the ink, the polarity of the solvent can cause darkening of the electrodes of the device.

[0005] One of the technical challenges of the present invention is to produce an electrophoretic color-variable ink without surface treatment of nanoparticles or dispersion stabilizers.

[0006] Additionally, one of the technical challenges of the embodiment is to improve color uniformity.

[0007] Additionally, one of the technical challenges of the embodiment is to prevent darkening of the display electrode.

[0008] Additionally, one of the technical challenges of the embodiment is to expand the color variability range of the electrophoretic ink.

[0009] The technical problems of the embodiment are not limited to those described in this article, but include those that can be understood through the description of the invention.

[0010] A reflective photonic crystal ink according to an embodiment includes nanoparticles; and a dispersion solvent in which the nanoparticles are dispersed, wherein the dispersion solvent may include a phenylalkylamine (PAA)-based material.

[0011] Additionally, in the embodiment, the dispersion solvent may include Phenylethylamine.

[0012] Additionally, in the embodiment, the dispersion solvent may include Phenylmethylamine.

[0013] In addition, the embodiment further includes a dispersion stabilizer, and the dispersion stabilizer may include at least one of solsperse, OLOA, AOT, and sorbitan.

[0014] Additionally, in embodiments, the nanoparticles may include hydroxyl groups on their surfaces.

[0015] Additionally, in the embodiment, the dispersion stabilizer may account for 10 wt% of the dispersion solvent.

[0016] Additionally, in the embodiment, the particle size of the nanoparticles is 180 nm to 200 nm, and the nanoparticles can occupy 25 vol% of the dispersion solvent.

[0017] Additionally, in embodiments, the nanoparticles may include silica (SiO2).

[0018] The reflective photonic crystal ink and the method for manufacturing the same according to the embodiment have a technical effect of allowing nanoparticles to be dispersed in a dispersion solvent without surface treatment or dispersion stabilizer to form a color-variable ink.

[0019] For example, the embodiment can form an electrophoretic color-variable ink without surface treatment by dispersing nanoparticles in a phenylalkylamine (PAA)-based dispersion solvent.

[0020] Additionally, the embodiment has a technical effect that can improve color uniformity.

[0021] For example, the embodiment can further improve color uniformity by adding a dispersion stabilizer.

[0022] Additionally, the embodiment has a technical effect capable of preventing darkening of the display electrode.

[0023] For example, the embodiment can prevent darkening of the display electrode by using a phenylalkylamine (PAA) dispersion solvent, which is a low-polarity solvent.

[0024] Additionally, the embodiment has a technical effect that can expand the variable range of colors in electrophoretic ink.

[0025] For example, embodiments can control and expand the variable range of colors by controlling the diameter and volume ratio of the nanoparticles.

[0026] Additionally, the embodiment has a technical effect of reducing standby power in home appliances and home interiors that implement colors.

[0027] The technical effects of the embodiments are not limited to those described in this article, but include those that can be understood through the description of the invention.

[0028] Figure 1 is a drawing showing a home appliance to which an embodiment is applied.

[0029] Figure 2 is a conceptual diagram of an electrophoretic device having a reflective photonic crystal ink according to an embodiment.

[0030] Figure 3 is a conceptual diagram of a reflective photonic crystal ink according to an embodiment.

[0031] Figure 4 is a graph showing the reflection spectrum according to the nanoparticle content in an embodiment.

[0032] Figure 5 is a graph showing the color according to the particle size of nanoparticles in an embodiment.

[0033] Figure 6 is a graph showing the color according to the type of alkyl group used as a dispersion solvent in the example.

[0034] Figure 7 is a conceptual diagram of a reflective photonic crystal ink according to a second embodiment.

[0035] Figure 8 is a drawing showing the characteristics of the dispersion solvent used in the example.

[0036] Figure 9 shows reliability data over time in an electronic device equipped with a reflective photonic crystal ink of a comparative example.

[0037] Figure 10 shows reliability data over time for an electronic device equipped with a reflective photonic crystal ink of the embodiment.

[0038] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. The attached drawings are intended to facilitate understanding of the embodiments disclosed in this specification, and the technical concepts disclosed in this specification are not limited by the attached drawings. Furthermore, when an element such as a layer, region, or substrate is referred to as existing "on" another component, this includes that it may be directly on the other element, or that other intermediate elements may be present therebetween.

[0039] The reflective photonic crystal ink described in this specification can be used in home appliances and interiors such as refrigerators, washing machines, stylers, TVs, displays, wallpaper, and sinks, and can be applied to products to which photonic crystal ink is applicable, even if a new product type is developed in the future.

[0040]

[0041] Fig. 1 is a drawing showing a home appliance (100) to which the embodiment is applied. In Fig. 1, a refrigerator is shown as the home appliance (100) to which the embodiment is applied, but the present invention is not limited thereto and may include home appliances, display devices, and home interior components that can have variable colors.

[0042] Referring to FIG. 1, a home appliance (100) according to an embodiment includes a plurality of panels (105), and the panels (105) may include reflective photonic crystal ink. The reflective photonic crystal ink can display color by reflected light rather than emitting light on its own like a semiconductor light-emitting element, and once an electric field is applied, the pores of the photonic crystal ink change to display a specific color, and thereafter, the color can be continuously displayed even without power supply, thereby preventing standby power consumption. In addition, since the color by reflected light can be changed by controlling the electric field for the same product, a variety of colors can be displayed, and there is a technical effect of improving aesthetics.

[0043]

[0044] Fig. 2 is a conceptual diagram of an electrophoretic element (115) having a reflective photonic crystal ink according to an embodiment. Referring to Fig. 2, in the embodiment, a reflective photonic crystal ink (117) is arranged within a cell of the electrophoretic element (115).

[0045] The reflective photonic crystal ink (117) includes nanoparticles (140) and a dispersion solvent in which the nanoparticles (140) are dispersed, and may have polarity. Accordingly, when power is applied, the nanoparticles (140) move in the direction of the electric field, and the arrangement of the reflective photonic crystal ink (117) may change. As the gap between the nanoparticles (140) narrows or increases, the wavelength at which the incident light is reflected changes, and a corresponding color may be displayed.

[0046]

[0047] Figure 3 is a conceptual diagram of a reflective photonic crystal ink according to an embodiment.

[0048] A reflective photonic crystal ink according to an embodiment can be manufactured by dispersing nanoparticles (140) in a phenylalkylamine (PAA) dispersion solvent without undergoing a separate surface treatment process.

[0049] For example, in the embodiment, the Phenylalkylamine (PAA) dispersion solvent may include, but is not limited to, phenylmethylamine (130) or phenylethylamine (135).

[0050] For example, (a) of FIG. 3 shows a process in which nanoparticles (140) combine with phenylmethylamine (130) to form a first reflective photonic crystal ink (142).

[0051] In addition, (b) of FIG. 3 shows a process in which nanoparticles (140) combine with phenylethylamine (135) to form a second reflective photonic crystal ink (145).

[0052] In an embodiment, the nanoparticles (140) may include organic polymers, oxides, or metal nanoparticles. The nanoparticles (140) may include hydroxyl groups on their surfaces. The nanoparticles (140) may include silica (SiO2), but are not limited thereto.

[0053] The above nanoparticles (140) may be synthesized by a process such as a sol-gel method, a co-precipitation method, or a hydrothermal synthesis method, but are not limited thereto.

[0054] In addition, the nanoparticles (140) have hydroxyl groups (OH) on their surfaces. - ), even if hydroxyl radicals (OH) are not included, through surface coating or surface modification - ) may be included.

[0055] Additionally, the nanoparticles (140) may have a spherical particle or a hollow structure.

[0056] Additionally, the refractive index of the nanoparticles (140) may be 1.3 to 3.0.

[0057] In addition, the particle diameter of the nanoparticles (140) may be 100 nm to 250 nm. In addition, the particle diameter of the nanoparticles (140) may be 120 nm to 200 nm. In addition, the particle diameter of the nanoparticles (140) may be 150 nm to 200 nm. The deviation of the particle diameter of the nanoparticles (140) may be 20 nm or less. In addition, the coefficient of variation (CV) of the nanoparticles (140) may be 10% or less.

[0058]

[0059] Meanwhile, in the embodiment, the dispersing solvent may include a phenylalkylamine (PAA)-based dispersing solvent. For example, in the embodiment, the dispersing solvent may include, but is not limited to, phenylmethylamine or phenylethylamine.

[0060] The above dispersion solvent can bind to the hydroxyl group present on the surface of the nanoparticle (140). In an embodiment, the dispersion solvent may be a phenylalkylamine (PAA) system in which an alkyl group is used alone or two or more alkyl groups are mixed.

[0061] In the reflective photonic crystal ink according to the embodiment, the volume ratio of the nanoparticles (140) may be 15 vol% to 40 vol%. In detail, the volume ratio of the nanoparticles (140) may be 20 vol% to 35 vol%.

[0062]

[0063] In the embodiment, a color-variable ink having a photonic crystal structure can be manufactured by mixing the nanoparticles (140) with the dispersion solvent and then mixing them using a mechanical method such as ultrasonic dispersion or ball mill dispersion. Then, the color-variable ink can be injected into a device having a transparent electrode substrate, and an ink injection port can be sealed to manufacture a photonic crystal display device.

[0064]

[0065] Fig. 4 is a graph simply expressing the reflection wavelength shown in the reflection spectrum according to the content of nanoparticles having an average particle diameter of 180 nm in an embodiment. Referring to Fig. 4, when the volume ratio of the particles of the reflective photonic crystal ink is 20% to 25%, the wavelength of the reflected light may be about 534 nm to 520 nm, and may have a green color.

[0066]

[0067] Additionally, when the volume ratio of the particles of the reflective photonic crystal ink is 25% to 35%, the wavelength of the reflected light may be about 500 nm to 520 nm and may have a cyan color.

[0068] As the particle size of nanoparticles increases, the distance between nanoparticles at the same volume ratio can increase. Therefore, when the volume ratio of nanoparticles with an average particle size of 200 nm is 20% to 25%, the wavelength of the reflected light can be 620 nm to 650 nm, and can have a red color. In addition, when the volume ratio of nanoparticles with an average particle size of 200 nm is 30% or more, it can have a green wavelength.

[0069]

[0070] Meanwhile, as the nanoparticle content increases, the distance between nanoparticles within the same dispersion area decreases, which may also reduce the size of the pores between nanoparticles. Accordingly, as the content of nanoparticles dispersed in the dispersion solvent increases, the central wavelength of the reflection spectrum may shift toward shorter wavelengths.

[0071] Therefore, the embodiment has a technical effect of being able to control the color of a reflective photonic crystal ink only by controlling the content of nanoparticles added to phenylalkylamine (PAA) without surface treatment of the nanoparticles.

[0072]

[0073] Figure 5 is a graph showing the reflection spectrum according to the particle size of nanoparticles in an embodiment.

[0074] Referring to Fig. 5, when the particle size of the nanoparticles added to the phenylalkylamine (PAA) dispersion solvent is about 180 nm, the wavelength of the reflection spectrum can be 520 nm to 565 nm, and a green color can be reflected.

[0075] In addition, when the particle size of the nanoparticles is about 200 nm, the wavelength of the reflection spectrum can be 625 nm to 740 nm, and a red color can be reflected. As the particle size of the nanoparticles increases at the same volume ratio of nanoparticles, the number of nanoparticles decreases, and the reflection spectrum can shift to a longer wavelength. Accordingly, the embodiment has a technical effect of controlling the color of the reflective photonic crystal ink by controlling the particle size of the nanoparticles added to phenylalkylamine (PAA) without surface treatment of the nanoparticles.

[0076]

[0077] Figure 6 is a graph showing the color according to the type of alkyl group used as a dispersion solvent in the example.

[0078] For example, the embodiment may include, but is not limited to, Phenylalkylamine (PAA)-based phenylmethylamine (Phenylmethylamine)(Methyl) or phenylethylamine (Phenylethylamine)(Ethyl).

[0079] In an embodiment, when a methyl group is used as a dispersion solvent in nanoparticles having an average particle diameter of 180 nm, the reflective photonic crystal ink can have a color ranging from cyan to green.

[0080] Additionally, when an ethyl group is used as a dispersion solvent in nanoparticles having an average particle diameter of 180 nm, the reflective photonic crystal ink can have a color range from blue to green.

[0081] Additionally, when an ethyl group is used as a dispersion solvent in nanoparticles with an average particle diameter of 200 nm, the reflective photonic crystal ink can have a color range from green to red.

[0082] As the length of the alkyl chain in the dispersion solvent increases, the color variable range of the reflection spectrum may increase, and even in the same dispersion solvent, the color range may vary depending on the average particle diameter of the nanoparticles.

[0083]

[0084] Table 1 below shows experimental examples 1 to 7 of reflective photonic crystal ink according to the examples.

[0085] Experimental examples 1 and 2 are experimental examples according to the first embodiment.

[0086] Experimental examples 3 to 7 are experimental examples according to the second embodiment described below.

[0087] Dispersion solvent charge control agent color quality device stability component dispersion solvent experiment example silica particle size content Phenylmethylamine Phenylethylamine dispersion stabilizer variable range operating voltage driving current 180nm 200nm 125vol% O--Cyan~Green~2V<10uA, @4V 225vol%-O-Blue~Green~2V<10uA, @4V 325vol%-O1wt%Blue~Green~2V<10uA, @4V 425vol%-O5wt%Blue~Green~2V<10uA, @4V 525vol%-O10wt%Blue~Green~2.5V<10uA, @4V 635vol%-O10wt%Blue~Cyan~2V<10uA, @4V 725vol%-O10wt%Green~Red~2V<10uA, @4V

[0088]

[0089] Next, Fig. 7 is a conceptual diagram of a reflective photonic crystal ink according to the second embodiment.

[0090] Referring to Fig. 7, when mixing the second nanoparticles (120) and the dispersion solvent (135) to produce a reflective photonic crystal ink (146), a dispersion stabilizer (150) may be added. The dispersion stabilizer (150) may be referred to as a charge control agent. The dispersion stabilizer (150) may include, but is not limited to, solsperse, OLOA, AOT, sorbitan, etc. The second nanoparticles (120) may adopt the technical characteristics of the nanoparticles (140) described above.

[0091] The above dispersion solvent can be combined with a hydroxyl group of the nanoparticle (120), and the dispersion stabilizer (150) can be combined with another hydroxyl group of the nanoparticle (120). The dispersion stabilizer has a technical effect of improving the color uniformity of the reflective photonic crystal ink. The dispersion stabilizer (150) can be 0.1 wt% to 20 wt% relative to the weight of the dispersion solvent. In detail, the dispersion stabilizer (150) can be 1 wt% to 10 wt% relative to the weight of the dispersion solvent, but is not limited thereto.

[0092]

[0093] Figure 8 is a drawing showing the characteristics of the dispersion solvent used in the examples and comparative examples.

[0094] Referring to Fig. 8, in the comparative reflective photonic crystal ink studied internally, aniline was used as a dispersion solvent.

[0095] Aniline had the advantage of having a wide color variability range, but when exposed to a continuous electric field, aniline oxidizes and polymerizes. As a result, the viscosity of aniline increases, making it difficult to use as ink, and there were problems with color discoloration. Furthermore, even in the absence of an electric field, when aniline is exposed to an external light source (light, UV-Vis, X-ray, etc.), aniline oxidizes and polymerizes similarly to when exposed to an electric field.

[0096] In addition, the melting point of aniline is approximately -6℃, which causes a problem in that its low-temperature stability is severely reduced in home appliances, interiors, and displays.

[0097]

[0098] Meanwhile, in the embodiment, the dispersion solvent may include a phenylalkylamine (PAA) system. For example, the phenylalkylamine (PAA) system dispersion solvent of the embodiment may include phenylmethylamine in the first embodiment and phenylethylamine in the second embodiment.

[0099]

[0100] Phenylmethylamine and Phenylethylamine, the dispersion solvents of the examples, have low dielectric constants, which can reduce damage to cells under continuous electric fields. Furthermore, the difference in refractive index with respect to nanoparticles is greater than 0.1, enabling color to be realized through reflection. Furthermore, their low melting point of approximately -40 degrees Celsius or lower enhances the reliability of devices at low temperatures. Furthermore, their high boiling point reduces volatility at room temperature, providing the advantage of high reliability.

[0101]

[0102] Next, Fig. 9 shows electrical reliability data over time in an electronic device equipped with a reflective photonic crystal ink of a comparative example, and Fig. 10 shows electrical reliability data over time in an electronic device equipped with a reflective photonic crystal ink of an example.

[0103]

[0104] Specifically, FIG. 9 shows electrical reliability data over time in an electronic device equipped with a reflective photonic crystal ink using Aniline as a dispersion solvent, and FIG. 10 shows electrical reliability data over time in an electronic device equipped with a reflective photonic crystal ink using Phenylethylamine as a dispersion solvent.

[0105] Referring to Fig. 9, the comparative example (Aniline application) confirmed a relatively high current value of 50 μA even at a low voltage of 2 V.

[0106] On the other hand, referring to Fig. 10, in the example (Phenylethylamine application), even though a voltage twice that of Aniline (approximately 4 V) was applied, the current measured in the electronic device cell was very low at approximately 8 μA.

[0107] Accordingly, it was confirmed that the example (Phenylethylamine application) was superior to the comparative example (Aniline application) in terms of long-term operation reliability of an electrophoretic device having a reflective photonic crystal structure.

[0108]

[0109] In the examples, color variation according to operating voltage can occur simply by dispersing nanoparticles in a phenylalkylamine (PAA) dispersion solvent without a dispersion stabilizer. Furthermore, adding a dispersion stabilizer in the examples can improve color uniformity. Furthermore, in the examples, when the particle size of the nanoparticles increases, the wavelength of reflected light can shift to longer wavelengths.

[0110] Therefore, the embodiment has a technical effect of being able to manufacture electrophoretic ink without separate surface treatment of nanoparticles by using a phenylalkylamine (PAA) system as a dispersion solvent, and having a wide color variable range.

[0111] In addition, the embodiment can be applied to home appliances, home interiors, etc. to improve aesthetics, and has the technical effect of reducing standby power by enabling color implementation without continuously supplying power.

[0112] The reflective photonic crystal ink and the method for manufacturing the same according to the embodiment have a technical effect of allowing nanoparticles to be dispersed in a dispersion solvent without surface treatment or dispersion stabilizer to form a color-variable ink.

[0113] For example, the embodiment can form an electrophoretic color-variable ink without surface treatment by dispersing nanoparticles in a phenylalkylamine (PAA)-based dispersion solvent.

[0114] Additionally, the embodiment has a technical effect that can improve color uniformity.

[0115] For example, the embodiment can further improve color uniformity by adding a dispersion stabilizer.

[0116] Additionally, the embodiment has a technical effect capable of preventing darkening of the display electrode.

[0117] For example, the embodiment can prevent darkening of the display electrode by using a phenylalkylamine (PAA) dispersion solvent, which is a low-polarity solvent.

[0118] Additionally, the embodiment has a technical effect that can expand the variable range of colors in electrophoretic ink.

[0119] For example, embodiments can control and expand the variable range of colors by controlling the diameter and volume ratio of the nanoparticles.

[0120] Additionally, the embodiment has a technical effect of reducing standby power in home appliances and home interiors that implement colors.

[0121] Although the present invention has been described above with reference to embodiments thereof, it will be readily understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

[0122] The embodiment can be used in electrophoretic devices, display devices, home appliances, and home interiors using reflective photonic crystal ink.

Claims

1. Nanoparticles; and Contains a dispersion solvent in which the above nanoparticles are dispersed, The above dispersion solvent is a reflective photonic crystal ink containing a phenylalkylamine (PAA)-based substance.

2. In paragraph 1, The above dispersion solvent is a reflective photonic crystal ink containing phenylethylamine.

3. In paragraph 1, The above dispersion solvent is a reflective photonic crystal ink containing phenylmethylamine.

4. In paragraph 1, Contains additional dispersion stabilizers, A reflective photonic crystal ink, wherein the dispersion stabilizer comprises at least one of solsperse, OLOA, AOT, and sorbitan.

5. In paragraph 1, The above nanoparticles are reflective photonic crystal inks containing hydroxyl groups on their surfaces.

6. In paragraph 4, A reflective photonic crystal ink, wherein the dispersion stabilizer comprises 1 to 10 wt% of the dispersion solvent.

7. In paragraph 6, The particle size of the above nanoparticles is 180 nm to 200 nm, A reflective photonic crystal ink, wherein the above nanoparticles account for 25 vol% to 35 vol%.

8. In paragraph 1, The above nanoparticles are reflective photonic crystal inks containing silica (SiO2).

9. A reflective photonic crystal electrophoretic device comprising the reflective photonic crystal ink of any one of claims 1 to 8.

10. A home appliance including a reflective photonic crystal electrophoretic device of Article 9.

Images