KR20180110718A - A coating composition, an electrochromic device and method for preparing the same - Google Patents

Abstract

The present application relates to a coating composition, an electrochromic device, and a method for preparing the same. The coating composition of the present application contains a first component and a second component, and the second component can form additional pores on an electrochromic layer. Thus the present invention can improve the color change speed of the device.

Description

[0001] The present invention relates to a coating composition, an electrochromic device, and a method for preparing the same.

The present application relates to a coating composition, an electrochromic device, and a method of manufacturing the same.

The term " electrochromism " refers to a phenomenon in which an optical property of an electrochromic material is changed by an electrochemical oxidation or reduction reaction. The electrochromic device is a device using the phenomenon described above. Specifically, the optical property of the electrochromic device is changed in such a manner that when the potential is applied to the device, the electrolyte ion is inserted into or removed from the electrochromic material, and at the same time, electrons move through the external circuit. Such an electrochromic device is capable of manufacturing devices with a large area with a small cost and has low power consumption, and is attracting attention as a smart window, a smart mirror, and other next-generation architectural window materials. However, it takes a long time to insert and desorb electrolytic ions to change the optical characteristics, which is disadvantageous in that the discoloration rate is slow. Studies on the improvement of the discoloration rate of electrochromic devices are mainly concerned with the introduction of low resistance electrode bodies. However, the new low-resistance electrode body has a problem of raising the cost of the product.

One object of the present invention is to provide an electrochromic device with improved color shift speed and a method of manufacturing the same.

Another object of the present invention is to provide an electrochromic device having improved color shift speed without increasing cost and a method of manufacturing the same.

The above and other objects of the present application can be all solved by the present application, which is described in detail below.

In one example of this application, the present application relates to a coating composition for electrochromic layer formation. The coating composition may comprise a first component comprising an electrochromic material and a second component immiscible with the first component.

In one example, the coating composition may comprise a first component and a second component in phase separation. Since the first component and the second component are phase-separated in a state where the electrochromic material is dispersed in the first component, the electrochromic material contained in the first component is not in contact with the second component and the physicochemical effect by the second component I can not accept.

In one example, the coating composition may comprise from 60% by volume to 99% by volume of the first component and from 1% by volume to 40% by volume of the second component. More specifically from 85% by volume to 95% by volume of the first component and from 5% by volume to 15% by volume of the second component. The volume percentage in the present application may mean the volume ratio of the first component to the second component included in the entire coating composition. In the above content range, the first component and the second component can maintain a proper phase-separation state. In addition, when the content range is satisfied, as described below, the second component is present in the electrochromic layer in an appropriate amount even after the coating composition is dried, so that additional voids can be formed in the electrochromic layer.

The first component and the second component may each contain at least one kind of solvent. If the first component and the second component can be phase-separated in the coating composition, the specific kind of the individual solvent contained in each component or the content ratio between individual solvents is not particularly limited.

In one example, the second component may comprise one or more solvents having a boiling point higher than that of any of the solvents that the first component comprises. Since the boiling point of the solvent contained in the second component is higher than the boiling point of the first component solvent on the premise that the first component and the second component are phase-separated, a process for forming the electrochromic layer described below, The second component may be present in the electrochromic layer without being completely evaporated even after the drying process of evaporating the first component or the sintering process of heating the electrochromic particles.

In another example, the boiling point of the solvent contained in the second component may be higher than -10 ° C to 100 ° C, which is the driving or storage temperature of a general electrochromic device. Thereby, the second component can be present in the device even when the electrochromic device is driven.

In one example, the first component may comprise at least one solvent selected from water, methanol, ethanol, propanol, and acetonitrile. In this case, the second component may include a carbonate-based solvent. The type of the carbonate-based solvent is not particularly limited, and may be selected from, for example, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylmethyl carbonate. Since the carbonate solvent easily forms a phase separation with the first component solvent and the boiling point of the carbonate solvent is higher than the boiling point of the first component or the driving temperature of the electrochromic device, It may remain in the electrochromic layer to form additional voids. Specifically, in the present application, in addition to the pores formed in the electrochromic layer due to the difference in diameters between the particulate electrochromic materials, it is possible to have additional pores due to the second component remaining in the electrochromic layer, It is possible to further widen the space in which the electrolyte ions involved in the discoloration exist and further intercalate the electrolyte ions. As a result, the additional pores formed by the second component can improve the color change speed of the device.

In one example, the second component may further comprise a glycol. The content of glycol contained in the second component is not particularly limited, but the content of glycol can be determined within a content range in which the second component can form a phase separation with the first component.

In one example, the second component may comprise a metal salt compound capable of providing a monovalent cation such as Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , or Cs ⁺ . More specifically, LiPF ₆ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiBF ₄ , LiSbF ₆ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAlO ₄ , LiAlCl ₄ , LiCo _0.2 Ni _0.56 Mn _0.27 O ₂ , LiCoO ₂ , LiSO ₃ CF ₃ or LiClO ₄ , & Lt ^; / RTI ^& gt ^; such as Li ^{< +} >. As described below, the electrolyte layer may also include the metal salts listed above. When the metal salt component contained in the electrolyte layer includes the second component existing in the electrochromic layer, The interlayer interfacial resistance can be reduced and the electrochromic rate can be improved.

The electrochromic material may be particulate matter. The specific shape of the particle shape is not particularly limited. For example, the electrochromic material may have a particle shape such as a spherical shape, an elliptic spherical shape, a rod shape, or an amorphous polyhedron. The size of the particulate electrochromic material may be in the range of, for example, 500 nm or less, specifically 300 nm to 400 nm. If the particles are spherical, elliptic spherical particles, the particle size can mean diameter. Also, if the particle has any other shape, the size of the particle can mean the length of the largest dimension in that shape.

In one example, an inorganic material may be used as the electrochromic material. For example, the electrochromic material may be a transition metal-based material such as an oxide or hydroxide of at least one of Cr, Mn, Fe, Co, Ni, Rh, and Ir; Or Prussian Blue; , ≪ / RTI > and the like. Or a reducing discoloring substance such as an oxide of any one selected from the group consisting of Ti, Nb, Mo, Ta and W. In this case, the oxidative discoloring substance may mean a substance that undergoes discoloration when an oxidation reaction occurs, and the reducing discoloring substance may denote a substance that discolors when a reducing reaction occurs.

In another example of the present application, the present application relates to an electrochromic device. The electrochromic device may include an electrolyte layer, an electrochromic layer, and a conductive layer sequentially. The electrochromic layer may be formed from the coating composition described above. For example, the electrochromic layer may be a sinter or a dried material for the coating composition.

In one example, the device of the present application may include the second component in the electrochromic layer in a state before the drive after each layer constituting the device is laminated. In the present application, pre-driving may mean before each voltage is applied to operate the electrochromic device in which each configuration is connected.

Specifically, the electrochromic layer may include a second component between the pores of the electrochromic material. Specifically, the second component may be present between the particulate electrochromic materials. In one example, a second component such as a carbonate-based solvent may be present in the electrochromic layer as a liquid phase. As described above, since the second component forms an additional void in the electrochromic layer in addition to the void due to the particulate electrochromic material, it is possible to improve the discoloration reaction rate of the device.

In one example, the electrolyte layer may comprise a second component. When both the electrochromic layer and the electrolyte layer include a common second component, the wetting between the electrochromic layer and the electrolyte layer interface is improved to reduce the interfacial resistance and improve the discoloration rate.

In addition to the second component, the electrolyte layer may contain electrolyte ions involved in electrochromism. Specifically, the electrolyte layer may include a metal salt compound capable of providing monovalent cations such as H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , or Cs ⁺ . For example, the electrolyte layer may be formed of a material selected from the group consisting of LiPF ₆ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiBF ₄ , LiSbF ₆ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAlO ₄ , LiAlCl ₄ , A lithium salt compound such as LiCo _0.2 Ni _0.56 Mn _0.27 O ₂ , LiCoO ₂ , LiSO ₃ CF ₃ or LiClO ₄ , or a sodium salt compound such as NaClO ₄ .

The kind of the conductive material used for the conductive layer is not particularly limited. For example, ITO (Indium Tin Oxide), In 2 O 3 (indium oxide), IGO (indium galium oxide), FTO (Fluor doped Tin Oxide), AZO (Aluminium doped Zinc Oxide), GZO (Galium doped Zinc Oxide) Transparent conductive compound such as ATO (Antimony-doped Tin Oxide), IZO (Indium-doped Zinc Oxide), NTO (Niobium-doped Titanium Oxide), ZnO (zink oxide), or CTO (Cesium Tungsten Oxide); Metal meshes comprising Ag, Cu, Al, Mg, Au, Pt, W, Mo, Ti, Ni or alloys thereof; Or a material such as OMO (oxide / metal / oxide) in which a metal layer is interposed between two metal oxide layers can be used for the conductive layer.

In one example, the electrochromic device may further include another conductive layer. In this case, depending on the relative position, the conductive layer may be referred to as an upper conductive layer and a lower conductive layer. For example, the device may include a lower conductive layer, an electrolyte layer, an electrochromic layer, and a top conductive layer in this order. The kind of the conductive material used for each conductive layer is as described above.

In one example, the electrochromic device may further include another electrochromic layer. In this case, the electrochromic layer described above may be referred to as a first electrochromic layer, and the added electrochromic layer may be referred to as a second electrochromic layer. For example, the device may include a lower conductive layer, a first electrochromic layer, an electrolyte layer, a second electrochromic layer, and a top conductive layer in this order. Each of the first and second electrochromic layers may include an electrochromic material having a different coloring property from each other. For example, when the first electrochromic layer includes an oxidative electrochromic material, the second electrochromic layer may include a reducing electrochromic material. The second electrochromic layer may also be referred to as an ion storage layer.

The second electrochromic layer may also be produced in the same manner as described in connection with the first electrochromic layer. The second electrochromic layer may have the same configuration as the first electrochromic layer, except that the electrochromic layer contains color-changing substances having different coloring characteristics.

The electrochromic device of the present application may further include a light-transmitting substrate. The light-transmitting substrate may be provided on the outer surface of the device, specifically, on the conductive layer. The translucent substrate may be, for example, a substrate having a visible light transmittance of about 60% to 95%. The visible light in the present application may mean a wavelength in the range of about 380 nm to 780 nm, more specifically a wavelength in the range of 550 nm.

If the transmittance in the above range is satisfied, the type of the substrate used is not particularly limited. For example, glass or polymer resin may be used. More specifically, a polyester film such as PC (Polycarbonate), PEN (poly (ethylene naphthalate)) or PET (poly terephthalate), an acrylic film such as poly (methyl methacrylate) Or a polyolefin film such as polypropylene (PP), but the present invention is not limited thereto.

In one example, the electrochromic device may further include a power source capable of applying a voltage to the conductive layer. The manner of electrically connecting the power source to the device is not particularly limited and may be suitably performed by those skilled in the art.

In another example related to the present application, the present application relates to a method of manufacturing an electrochromic device. The electrochromic layer included in the electrochromic device manufactured according to the present application may be prepared by a wet coating method instead of a dry coating such as vapor deposition. The specific wet coating method is not particularly limited and includes, for example, spin coating, dip coating, bar coating, spray coating, gravure coating, microgravure coating, flow coating, capillary coating, slot die coating, Etc. may be used.

In one example, the method of the present application may comprise applying the coating composition onto a conductive layer, followed by drying and / or sintering. The composition of the coating composition is the same as mentioned above.

In one example, the drying or sintering of the applied coating composition may occur at a temperature lower than the boiling point of either of the second components. For example, when a carbonate-based solvent is included in the second component, the drying may be performed at 130 ° C or lower for several seconds to several tens of minutes.

In another example, the drying or sintering of the applied coating composition may be at a temperature above the boiling point of the first component. For example, when the first component comprises water, the drying may be performed at a temperature of 100 ° C or higher for several seconds to several tens of minutes.

According to one example of the present application, an electrochromic device having improved coloring speed without increasing the manufacturing cost can be provided.

1 is an image of the surface of the electrochromic film of Examples 1 and 2 and Comparative Example 1 (reference).
Fig. 2 is a graph showing changes in driving characteristics observed in the electrochromic devices of Examples 3 to 5 and Comparative Example 2 (reference). Fig. Specifically, FIG. 2 (a) shows a current change and FIG. 2 (b) shows a change in charge amount.
3 is a graph showing changes in driving characteristics of the electrochromic films of Examples 6 to 8 and Comparative Example 2 (reference). Specifically, FIG. 3 (a) shows a current change and FIG. 3 (b) shows a change in charge amount.

Hereinafter, the present application will be described in detail by way of examples. However, the scope of protection of the present application is not limited by the following embodiments.

The electrochromic layer  Pole Comparison

Example  One

WO ₃ 90% by volume of water-dispersed particles (H ₂ O) and 10% by volume of PC (propylene carbonate) was coated on the ITO layer of the PET / ITO laminate and dried at 130 ° C for 5 minutes to provide electrochromic A film was prepared. The surface of the electrochromic film formed from the coating composition was then photographed with a scanning electron microscope (SEM). The photographed image is shown in Fig.

Example  2

A film was prepared in the same manner as in Example 1 except that the content of PC (propylene carbonate) in the coating composition was adjusted to 5 vol%, and its surface was photographed with a scanning electron microscope (SEM). The photographed image is shown in Fig.

Comparative Example  One

A film was prepared in the same manner as in Example 1, except that PC (propylene carbonate) was not included in the coating composition, and its surface was photographed with a scanning electron microscope (SEM). The photographed image is shown in Fig.

In Fig. 1, the dark part appearing in each image means void. It can be confirmed that more voids are observed in Examples 1 and 2 than in Comparative Example 1. [

Driving speed comparison

Example  3

The electrochromic film prepared in the same manner as in Example 1 was laminated with LiClO ₄ And PC (propylene carbonate), and a voltage of a predetermined magnitude was alternately applied for a predetermined period of time. Then, the change of current and charge amount related to the driving characteristics of the device was observed using a potentiostat device. The results are shown in Figs. 2 (a) and 2 (b).

Example  4

Current and charge changes were observed in the same manner as in Example 3, except that the content of PC (propylene carbonate) in the coating composition was changed to 20% by volume. The results are shown in Figs. 2 (a) and 2 (b).

Example  5

The current and charge changes were observed in the same manner as in Example 3 except that the content of PC (propylene carbonate) in the coating composition was changed to 30% by volume. The results are shown in Figs. 2 (a) and 2 (b).

Example  6

In the formation of the coating composition, a change in current and charge amount was observed in the same manner as in Example 3, except that the 10 volume% component further contained 1 M of LiClO ₄ . The results are shown in Figs. 3 (a) and 3 (b).

Example  7

In the formation of the coating composition, the change in current and charge amount was observed in the same manner as in Example 4, except that the 20% by volume component was further modified to include 1 M of LiClO ₄ . The results are shown in Figs. 3 (a) and 3 (b).

Example  8

In the formation of the coating composition, a change in current and charge amount was observed in the same manner as in Example 5, except that 30% by volume of the component was further changed to include 1 M of LiClO ₄ . The results are shown in Figs. 3 (a) and 3 (b).

Comparative Example  2

A film was prepared in the same manner as in Comparative Example 1, and the changes in current and charge amount were observed in the same manner as in Example 3. [ The result is the same as the reference in each of Figs. 2 (a), 2 (b), 3 (a) and 3 (b).

In both FIG. 2 and FIG. 3, the peak current and charge of Comparative Example 2 are the lowest. On the contrary, in Examples 3 to 8, a higher level of electric current and charge than Comparative Example 2 was observed. This means that the coloring speed and performance of the device of the embodiment are superior to those of the device of the comparative example.

Claims (14)

A first component comprising an electrochromic material; And a second component that is immiscible with the first component. The coating composition of claim 1, comprising from 60 vol% to 99 vol% of the first component and from 1 vol% to 40 vol% of the second component. The coating composition of claim 1, wherein the second component comprises at least one solvent having a higher boiling point than any solvent that the first component comprises. 4. The coating composition of claim 3, wherein the first component comprises at least one solvent selected from water, methanol, ethanol, propanol, and acetonitrile. The method of claim 4, wherein the second component comprises at least one carbonate-based solvent selected from ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC) Coating composition. 7. The coating composition of claim 6, wherein the second component further comprises a glycol. The coating composition of claim 6, wherein the second component further comprises a metal salt component The method of claim 7, wherein the metal salt is selected from the group consisting of LiPF ₆ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiBF ₄ , LiSbF ₆ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAlO ₄ , LiAlCl ₄ , LiCo _{0 . 2} Ni _{0 . 56} Mn _{0 . 27} O ₂ , LiCoO ₂ , LiSO ₃ CF _3, and LiClO ₄ . The coating composition according to claim 1, wherein the electrochromic material is a particulate material having a diameter of 500 nm or less. 10. The coating composition of claim 9, wherein the electrochromic material comprises an oxidative chromatic material or a reducing chromatic material. An electrolyte layer; A electrochromic layer formed from the coating composition according to any one of claims 1 to 10; And a conductive layer in this order. The electrochromic device according to claim 11, wherein the electrochromic layer contains a second component between the pores of the particulate electrochromic material. 12. The electrochromic device according to claim 11, wherein the electrolyte layer comprises a second component. A process for producing an electrochromic device, comprising: applying a coating composition according to any one of claims 1 to 10 onto a conductive layer, followed by drying or sintering to form an electrochromic layer.

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