Patent ID: 12228836

DETAILED DESCRIPTION

Advantages and features of the present disclosure and methods of accomplishing the same may be understood more readily by reference to the following detailed description of embodiments and the accompanying drawings. However, the present disclosure may be embodied in different forms, and these embodiments are provided only to make this disclosure thorough and complete and to fully convey the scope of the present disclosure to those skilled in the art, and thus the present disclosure is defined only by the scope of the appended claims. Like reference numerals denote like elements throughout specification.

Terms used herein are not for limiting the present disclosure but for describing the embodiments. Unless otherwise defined, terms used in the embodiments may be understood as meanings generally known to those skilled in the art. The terms of a singular form may include plural forms unless otherwise specified. It will be further understood that the terms “comprises” and/or “comprising”, when used ‘in this description, specify the presence of stated elements, steps, operations, and/or components, but do not preclude the presence or addition of one or more other elements, steps, operations, and/or components.

In the description, it is to be noted that when a surface (or layer) is referred to as being ‘on’ another surface (or layer) or substrate, it may be directly formed on another surface (or layer) or substrate, or a third surface (or layer) may also be interposed therebetween. Although terms like a first, a second, and a third are used to describe various regions and surfaces (layers) in various embodiments of the description, these regions and surfaces (layers) should not be limited to these terms. These terms are used only to tell one region or surface (layer) from another region or surface (layer).

Additionally, the embodiments described in the description will be explained with reference to the cross-sectional views and/or plan views as ideal example views of the present disclosure. In the drawing, the thicknesses of films and regions are exaggerated for effective description of the technical contents. Therefore, a form of an example view may be modified by a manufacturing method and/or tolerance. Accordingly, the embodiments of the present disclosure are not limited to the specific shape illustrated in the example views, but may include other shapes that are created according to manufacturing processes. Thus, areas exemplified in the drawings have general properties, and shapes of the exemplified areas are used to illustrate a specific shape of a device region. Therefore, this should not be construed as limited to the scope of the present disclosure.

FIG.1is a flowchart for describing a method of manufacturing a thin film electrode for an electrochromic device according to an embodiment of the inventive concept.

Referring toFIG.1, a method of manufacturing a thin film electrode for an electrochromic device according to an embodiment of the inventive concept may include: synthesizing insoluble Prussian blue nanoparticles (S1); adding a surfactant to the insoluble Prussian blue nanoparticles to form water-soluble Prussian blue nanoparticles (S2); adding a solvent and a binder to the water-soluble Prussian blue nanoparticles to form a mixed solution (S3); applying the mixed solution onto an electrode (S4); and performing a drying process on the electrode applied with the mixed solution (S5).

The synthesizing of insoluble Prussian blue nanoparticles (S1) may include a process of mixing a solution containing ferrocyanide ions ([Fe(CN)6]4−) with a solution containing iron ions (Fe3+). The insoluble Prussian blue nanoparticles may be precipitated through the mixing process.

The Prussian blue nanoparticles may be an inorganic electrochromic material containing iron. The Prussian blue nanoparticles may be an anodic coloring material that is colored upon an anodic reaction, and is bleached upon a cathodic reaction. The Prussian blue nanoparticles are materials having stable oxidation state, and may be blue in color with Formula of Fe4III[FeII(CN)6]3in the oxidation state, and may be transparent with Formula of Fe4II[FeII(CN)6]3as turning to a reduced state in response to an externally applied voltage. That is, basically the Prussian blue nanoparticles turn into a different color due to the oxidation/reduction reaction of iron, and thus come in various colors (e.g., yellow, green, and the like) according to the number of valence electrons present in iron. In general, the Prussian blue nanoparticles may be insoluble.

The method of manufacturing a thin film electrode for an electrochromic device according to an embodiment of the inventive concept may include adding a surfactant to the insoluble Prussian blue nanoparticles to form water-soluble Prussian blue nanoparticles (S2). That is, the adding of a surfactant to the insoluble Prussian blue nanoparticles may result in forming water-soluble Prussian blue nanoparticles.

Through the surfactant, the insoluble Prussian blue nanoparticles may be modified into water-soluble Prussian blue nanoparticles, and accordingly, the water-soluble Prussian blue nanoparticles may be dried at room temperature upon a subsequent drying process.

The surfactant may include a salicylic acid-based compound. For example, the surfactant may include at least one of lithium salicylate, sodium salicylate, or potassium salicylate. The surfactant may be contained in an amount of 0.5 parts by weight to 1.5 parts by weight with respect to 100 parts by weight of the insoluble Prussian blue nanoparticles.

The method of manufacturing a thin film electrode for an electrochromic device according to an embodiment of the inventive concept may include adding a solvent and a binder to the water-soluble Prussian blue nanoparticles to form a mixed solution (S3).

The solvent may include a polar solvent. For example, the solvent may include water or alcohol. More specifically, the solvent may include water, ethanol, methanol, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), or the like.

The binder may include an alkoxysilane-based compound. For example, the binder may include tetraethyl orthosilicate (TEOS).

Before the applying of the mixed solution to an electrode, the method may further include applying a surface modification material onto the electrode, and performing a heat treatment process on the electrode applied with the surface modification material.

The surface modification material may include water and polyethyleneimine (PEI). The polyethyleneimine (PEI) may include branched polyethyleneimine (PEI) or linear polyethyleneimine (PEI). The polyethyleneimine (PEI) may be contained in an amount of 0.05 parts by weight to 0.5 parts by weight with respect to 100 parts by weight of water. The surface modification material is a material that does not affect the electrical properties and transmittance of an electrode, and may serve to effectively bond the electrode with an electrochromic material.

The method of manufacturing a thin film electrode for an electrochromic device according to an embodiment of the inventive concept may include applying the mixed solution onto an electrode (S4).

The applying of the mixed solution onto the electrode may include at least one of spin coating, dip coating, bar coating, spray coating, slot die coating, doctor blade, or screen printing.

The electrode may include a transparent electrode. For example, the electrode may include indium tin oxide (ITO).

The electrode may be an electrode formed on a substrate. That is, the mixed solution may be applied to the electrode on the substrate. The substrate may include at least one of a plastic substrate, a flexible substrate, a cellulose substrate, or a fiber substrate. The method of manufacturing a thin film electrode for an electrochromic device according to an embodiment of the inventive concept may not include a heat treatment process, and thus may use a substrate having poor heat resistance without limitation.

The method of manufacturing a thin film electrode for an electrochromic device according to an embodiment of the inventive concept may include performing a drying process on the electrode applied with the mixed solution (S5).

The drying process may be performed at 15° C. to 30° C. The drying process may be performed for 30 seconds to 15 minutes. The drying process may not include a heat treatment process.

Typically, a drying process is required at a high temperature (e.g., 120° C. or higher) to apply Prussian blue to the electrode, and thus, a heat treatment process is required to be accompanied. However, increasing time for the heat treatment causes the electrode to be delaminated from the substrate or the electrode to be deformed.

In the manufacture of the thin film electrode for an electrochromic device according to an embodiment of the inventive concept, the electrode applied with the mixed solution is naturally dried at room temperature, and thus a heat treatment process may not be required. In addition, the deliminating of the electrode from the substrate or the deforming of the electrode may be prevented to allow various substrates to be used without limitation. In addition, in the manufacture of the thin film electrode for an electrochromic device, process cost and time may be reduced.

In some embodiments, after the performing of a drying process on the electrode applied with the mixed solution, the method may further include performing a heat treatment process after an aging period of 24 hours. The heat treatment process may be performed at 120° C. In this case, the performing of the heat treatment process after the aging period of 24 hours may prevent the electrode being delaminated from the substrate.

FIG.2is a perspective view for describing a thin film electrode for an electrochromic device according to an embodiment of the inventive concept.FIG.2shows a thin film electrode for an electrochromic device manufactured according to the method of manufacturing a thin film electrode for an electrochromic device described above with reference toFIG.1.

Referring toFIG.2, the thin film electrode for an electrochromic device according to an embodiment of the inventive concept may include a transparent electrode100, a surface modification layer200, and an electrochromic layer300. The electrochromic layer300may be disposed on the transparent electrode100. The surface modification layer200may be interposed between the transparent electrode100and the electrochromic layer300. The transparent electrode100and the electrochromic layer300may adhere to each other through the surface modification layer200. Although the surface modification layer200is enlarged and shown for description, the thickness of the surface modification layer200may be smaller than that shown inFIG.2.

For example, the transparent electrode100may include indium tin oxide (ITO).

The surface modification layer200may include water and polyethyleneimine (PEI). The polyethyleneimine (PEI) may include branched polyethyleneimine (PEI) or linear polyethyleneimine (PEI). The polyethyleneimine (PEI) may be contained in an amount of 0.05 parts by weight to 0.5 parts by weight with respect to 100 parts by weight of the water.

The transparent electrode100and the electrochromic layer300may adhere to each other through the surface modification layer200. More specifically, a chemical bond may be formed between the transparent electrode100and the electrochromic layer300through the surface modification layer200.

The electrochromic layer300may include Prussian blue nanoparticles made water soluble through a surfactant. The surfactant may include a salicylic acid-based compound. For example, the surfactant may include at least one of lithium salicylate, sodium salicylate, or potassium salicylate. According to an embodiment of the inventive concept, the electrochromic layer300may be dried at room temperature.

When a voltage is applied to the thin film electrode for an electrochromic device, electrons may easily travel through the surface modification layer200. That is, even when the thin film electrode for an electrochromic device of an embodiment of the inventive concept includes the surface modification layer200, electrons may travel through the surface modification layer200. In addition, adhesion properties between the transparent electrode100and the electrochromic layer300may be further enhanced through the surface modification layer200.

FIGS.3A to3Dshow results obtained by measuring electrochemical properties of a thin film electrode for an electrochromic device according to an embodiment of the inventive concept through cyclic voltammetry.

Specifically,FIG.3Ashows results obtained by measuring electrochemical properties of a thin film electrode (KPB (reference)) for an electrochromic device manufactured using potassium hexacyanoferrate (K4Fe(CN)6) through cyclic voltammetry.FIG.3Bshows results obtained by measuring electrochemical properties of a thin film electrode (Li-sal PB) for an electrochromic device manufactured using lithium salicylate as a surfactant through cyclic voltammetry.FIG.3Cshows results obtained by measuring electrochemical properties of a thin film electrode (Na-sal PB) for an electrochromic device manufactured using sodium salicylate as a surfactant through cyclic voltammetry.FIG.3Bshows results obtained by measuring electrochemical properties of a thin film electrode (K-sal PB) for an electrochromic device manufactured using potassium salicylate as a surfactant through cyclic voltammetry. The cyclic voltammetry was measured only with respect to turning into blue and transparent colors of a thin film electrode, and the color of the thin film electrode turns to blue at (+) voltage and turns to transparent at (−) voltage.

Referring toFIGS.3A to3D, it is seen that electrons are readily injected/discharged in all thin film electrodes for electrochromic devices. However, it is observed that the amount of flowing current decreases in the order of the thin film electrode (Li-sal PB) for an electrochromic device manufactured using lithium salicylate>the thin film electrode (Na-sal PB) for an electrochromic device manufactured using sodium salicylate>the thin film electrode (K-sal PB) for an electrochromic device manufactured using potassium salicylate.

FIGS.4A to4Dshow X-ray photoelectron spectroscopy (XPS) results of a thin film electrode for an electrochromic device according to an embodiment of the inventive concept.

Specifically,FIG.4Ashows X-ray photoelectron spectroscopy (XPS) results of a thin film electrode (KPB (reference)) for an electrochromic device manufactured using potassium hexacyanoferrate (K4Fe(CN)6) through cyclic voltammetry.FIG.4Bshows X-ray photoelectron spectroscopy (XPS) results of a thin film electrode (Li-sal PB) for an electrochromic device manufactured using lithium salicylate as a surfactant through cyclic voltammetry.FIG.4Cshows X-ray photoelectron spectroscopy (XPS) results of a thin film electrode (Na-sal PB) for an electrochromic device manufactured using sodium salicylate as a surfactant through cyclic voltammetry.FIG.4Dshows X-ray photoelectron spectroscopy (XPS) results of thin film electrodes (KPB (reference), Li-sal PB, and Na-sal PB) for electrochromic devices.

Referring toFIGS.4A to4D, peaks corresponding to targeted elements were identified in all thin film electrodes for electrochromic devices. In particular, peaks corresponding to elements included in Prussian blue were identified. In addition, referring toFIGS.4B and4C, peaks corresponding to cations included in salicylic acid were identified. Referring toFIG.4D, it was seen that the amount of potassium ions was decreased compared to that of the thin film electrode (KPB (reference)) for an electrochromic device.

FIG.5is a perspective view for describing an electrochromic device according to an embodiment of the inventive concept.

Referring toFIG.5, an electrochromic device according to an embodiment of the inventive concept may include a first transparent electrode101, a second transparent electrode102, a first surface modification layer201, a second surface modification layer202, a first electrochromic layer301, a second electrochromic layer302, and an electrolyte layer400.

The first transparent electrode101and the second transparent electrode102facing each other may be provided. The electrolyte layer400may be disposed between the first transparent electrode101and the second transparent electrode102. The first electrochromic layer301may be disposed between the first transparent electrode101and the electrolyte layer400. The second electrochromic layer302may be disposed between the second transparent electrode102and the electrolyte layer400. The first surface modification layer201may be interposed between the first transparent electrode101and the first electrochromic layer301. The second surface modification layer202may be interposed between the second transparent electrode102and the second electrochromic layer302.

The first transparent electrode101and the first electrochromic layer301may adhere to each other through the first surface modification layer201. More specifically, a chemical bond may be formed between the first transparent electrode101and the first electrochromic layer301through the first surface modification layer201. The second transparent electrode102and the second electrochromic layer302may adhere to each other through the second surface modification layer202. More specifically, a chemical bond may be formed between the second transparent electrode102and the second electrochromic layer302through the second surface modification layer202. Although the first and second surface modification layers201and202are enlarged and shown for description, the thicknesses of the first and second surface modification layers201and202may be smaller than those shown inFIG.5.

The first transparent electrode101and the second transparent electrode102may include at least one of a metal oxide electrode, a stacked electrode having an oxide-metal-oxide (OMO) structure, a polymer electrode (e.g., PEDOT:PSS, and the like), or a carbon-based electrode. For example, the metal oxide electrode may include at least one of indium tin oxide (ITO), fluorine doped tin oxide (FTO), or antimonium doped zinc oxide (AZO). For example, the polymer electrode may include PEDOT:PSS, and the like. For example, the carbon-based electrode may include at least one of graphene or carbon nanotube (CNT).

At least one of the first surface modification layer201or the second surface modification layer202may include water and polyethyleneimine (PEI). The polyethyleneimine (PEI) may include branched polyethyleneimine (PEI) or linear polyethyleneimine (PEI). The polyethyleneimine (PEI) may be contained in an amount of 0.05 parts by weight to 0.5 parts by weight with respect to 100 parts by weight of the water.

At least one of the first electrochromic layer301or the second electrochromic layer302may include Prussian blue nanoparticles made water soluble through a surfactant. The surfactant may include a salicylic acid-based compound. For example, the surfactant may include at least one of lithium salicylate, sodium salicylate, or potassium salicylate. According to an embodiment of the inventive concept, at least one of the first electrochromic layer301or the second electrochromic layer302may be dried at room temperature.

In some embodiments, the first electrochromic layer301and the second electrochromic layer302may include electrochromic materials having different driving directions. For example, the first electrochromic layer301may include a cathodic coloring material, and the second electrochromic layer302may include an anodic coloring material. For example, the first electrochromic layer301may include at least one of a metal oxide or a polymer. For example, the metal oxide may include at least one of tungsten oxide (WO3) or molybdenum oxide (MoO3), and the polymer may include PEDOT:PSS, and the like. The second electrochromic layer302may include at least one of a metal oxide such as NiOxor V2O5, a polymer such as PANI, or Prussian blue nanoparticles made water soluble through a surfactant.

For another example, the first electrochromic layer301may include an anodic coloring material, and the second electrochromic layer302may include a cathodic coloring material. For example, the first electrochromic layer301may include at least one of a metal oxide such as NiOxor V2O5, a polymer such as PANI, or Prussian blue nanoparticles made water soluble through a surfactant, and the second electrochromic layer302may include at least one of a metal oxide or a polymer. For example, the metal oxide may include at least one of tungsten oxide (WO3) or molybdenum oxide (MoO3). The polymer may include PEDOT:PSS, and the like.

The electrolyte layer400may include an electrolyte. The electrolyte may include a monovalent cation and a monovalent anion. For example, the monovalent cation may be H+, Li+, Na+, K+, or NH+. For example, the electrolyte may include at least one of LiClO4, LiBF4, LiPF6, or LiTFSI(tri(fluoromethansulfonimide)lithium salt). The electrolyte layer400may further include a solvent, the solvent may include organic solvents such as water, ethanol, methanol, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), and the like, and the above organic solvents may be used alone or in an appropriate combination. When a voltage is applied to an electrochromic device from the outside, electrons may easily travel through the first surface modification layer201and the second surface modification layer202. That is, although the electrochromic device of an embodiment of the inventive concept includes the first surface modification layer201and the second surface modification layer202, electrons may travel through the first surface modification layer201and the second surface modification layer202. In addition, adhesion properties between the first transparent electrode101and the first electrochromic layer301may be further enhanced through the first surface modification layer201. Adhesion properties between the second transparent electrode102and the second electrochromic layer302may be further enhanced through the second surface modification layer202.

FIG.6shows results obtained by measuring transmittance according to wavelength of an electrochromic device according to an embodiment of the inventive concept. In this case, the first electrochromic layer301includes tungsten oxide (WO3), and the second electrochromic layer302includes Prussian blue nanoparticles made water soluble through a surfactant. More specifically, an electrochromic electrode with the first transparent electrode101bonded to the first electrochromic layer301containing tungsten oxide (WO3) as a working electrode, and the second transparent electrode102as a counter electrode was manufactured, and subjected to measurement of transmittance according to wavelength. In this case, each of a thin film electrode (KPB (reference)) for an electrochromic device manufactured using potassium hexacyanoferrate (K4Fe(CN)6); a thin film electrode (Li-sal PB) for an electrochromic device manufactured using lithium salicylate as a surfactant; a thin film electrode (Na-sal PB) for an electrochromic device manufactured using sodium salicylate as a surfactant, and a thin film electrode (K-sal PB) for an electrochromic device manufactured using potassium salicylate as a surfactant were configured as a counter electrode.

The electrochromic device was driven at a voltage of −1.5 V (blue)/+1.5 V (transparent). In this case, the voltage and the sign of the thin film electrode for an electrochromic device described with reference toFIGS.3A to3Dare different due to the fact that the second transparent electrode102bonded to the second electrochromic layer302containing Prussian blue nanoparticles was used as a counter electrode.

Referring toFIG.6, it was seen that all electrochromic devices were operable. However, it is seen that the electrochromic device with a counter electrode of a thin film electrode (K-sal PB) for an electrochromic device manufactured using potassium salicylate had the greatest transmittance conversion. In addition, it was seen that the case had the greatest and most distinct color conversion even with the naked eye.

According to a method of manufacturing a thin film electrode for an electrochromic device of the present disclosure, an electrode applied with a mixed solution containing Prussian blue nanoparticles may be naturally dried at room temperature. That is, the drying process may not include a heat treatment process. Accordingly, the deliminating of the electrode from the substrate or the deforming of the electrode may be prevented to allow various substrates to be used without limitation. In addition, in the manufacture of the thin film electrode for an electrochromic device, process cost and time may be reduced.

Although the embodiments of the inventive concept have been described above with reference to the accompanying drawings, those skilled in the art to which the inventive concept pertains may implement the inventive concept in other specific forms without changing the technical idea or essential features thereof. Therefore, the above-described embodiments are to be considered in all aspects as illustrative and not restrictive.