KR102010734B1 - An Electrochromic Device - Google Patents

Abstract

The present application relates to an electrochromic device and a method of manufacturing the same. The present application including a novel ion storage layer material provides an electrochromic device which is excellent in durability and thin film productivity, and has improved color change rate compared to the prior art.

Description

Electrochromic Device

The present application relates to an electrochromic device. In particular, the present application relates to an electrochromic device having improved color change efficiency and switching time.

Electrochromism refers to a phenomenon in which optical properties such as color or light transmittance of an electrochromic active material change depending on an electrochemical oxidation and reduction reaction. Electrochromic devices using such a phenomenon can be manufactured in a large area of the device at a low cost, and has a low power consumption, attracting attention in various fields such as smart windows, smart mirrors, electronic paper and the like.

1 is a cross-sectional view of a general electrochromic device. As shown in the drawing, the electrochromic device 100 includes a first electrode layer 110, an electrochromic layer 120 provided on the first electrode layer 110, an electrolyte layer 130 provided on the electrochromic layer, and the It may include an ion storage layer 140 provided on the electrolyte layer, and a second electrode layer 150 provided on the ion storage layer. Although not shown, a substrate formed from transparent glass or polymer resin may be further included on the outer surfaces of the electrodes 110 and 150.

In general, the electrochromic layer and / or the ion storage layer may include an inorganic material such as tungsten oxide (WOx) or lithium nickel oxide (LiNiOx) as an electrochromic material. Specifically, when a specific potential is applied to the electrode, electrolyte ions such as H ⁺ , or Li ⁺ , Na ⁺ move through the electrolyte layer between the electrochromic layer and the ion storage layer, and at the same time electrons are transferred through the external circuit. As it is injected into or disengaged from the electrochromic layer, oxidation / reduction reactions of the electrochromic material are alternately performed, and coloration or bleaching of the electrochromic layer or the ion storage layer is performed. As described above, since the change of the optical properties of the electrochromic device is premised on the movement of the ionic material, the color change takes a predetermined time, that is, a switching time, thereby improving the color change efficiency and reducing the color change time. Skill is required.

One object of the present application is to provide an electrochromic device having excellent discoloration efficiency and improved discoloration speed.

Another object of the present application is to provide an electrochromic device having a sufficient discoloration effect even in a thin film.

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

The present application relates to an electrochromic device. The electrochromic device may include two opposing electrodes, an electrochromic layer, an electrolyte layer, and an ion storage layer.

The electrode may refer to a configuration capable of supplying electric charges to the electrochromic layer. In one example, the electrode may be a transparent conductive oxide (TCO), a conductive polymer, an Ag nanowire, or a metal mesh. It may be formed including any one or more of (Metal mesh). More specifically, ITO (Indium Tin Oxide), FTO (Fluor doped Tin Oxide), AZO (Aluminium doped Zinc Oxide), GZO (Galium doped Zinc Oxide), ATO (Antimony doped Tin Oxide), IZO (Indium doped Zinc Oxide) Niobium doped Titanium Oxide (NTO), ZnO, Oxide / Metal / Oxide (OMO), or CTO may be used as the electrode material, but is not limited thereto. In another example, the electrode layer may have a structure in which two or more electrode materials are stacked in a plurality of layers.

The method for forming the electrode layer is not particularly limited, and known methods can be used without limitation. For example, an electrode layer may be provided by forming an electrode material including transparent conductive oxide particles in a thin film form on a transparent glass substrate through a sputtering process. The electrode layer may have a thickness of 150 nm or more, 200 nm or more, or 300 nm or more within the range of 1 nm to 1 μm. The upper limit of the thickness of the electrode layer is not particularly limited, but the electrode layer may have a thickness of 800 nm or less, 700 nm or less, or 500 nm or less for low resistance.

In one example, the electrode layer may have a light transmittance in the range of 70% to 95% with respect to visible light. In the present application, the visible light may refer to light having a wavelength in the range of about 350 nm to 750 nm, and more specifically, to light having a wavelength of 550 nm.

The electrochromic layer may include an electrochromic material that changes color according to an electrical signal. Examples of electrochromic materials that can be used include conductive polymers, organic chromic materials, and / or inorganic chromic materials. The conductive polymer may be polypyrrole, polyaniline, polypyridine, polyindole, polycarbazole, or the like, and an organic discoloring material may be a material such as viologen, anthraquinone, phenocyazine, but is not limited thereto. no.

The electrochromic layer may include an inorganic color change material. For example, one or more oxides of oxides of Ti, Nb, Mo, Ta, W, V, Cr, Mn, Fe, Co, Ni, Rh, and Ir may be included as an inorganic discoloration material. More specifically, the electrochromic layer of the present application may include nickel oxide (NiO _x ) as an oxidative discoloring material, and the nickel oxide may be dark brown by an oxidation reaction depending on a voltage applied to an electrode layer. Can be colored.

In the above reaction, when the color change material included in the electrochromic layer is decolorized, the electrochromic device transmits incident light, and when colored, the optical characteristics of the electrochromic device may be changed while the amount of incident light is reduced. The coloring and decolorizing reactions may occur alternately depending on the polarity of the applied voltage, or the direction of current flow.

In one example, the electrochromic layer may have a thickness of 10 nm to 450 nm. In addition, the electrochromic layer may have a transmittance of 20% to 50% of visible light when colored, and a transmittance of 50% to 75% of visible light when decolored.

The ion storage layer may refer to a layer in which charge particles necessary for redox reaction of the electrochromic layer may be inserted or desorbed, and thus may be involved in the discoloration reaction. In the prior art, in consideration of the role of the ion storage layer, a complementary electrochromic material was used for each of the electrochromic layer and the ion storage layer. For example, when the electrochromic layer includes a reducing discoloration material such as tungsten oxide (WO _x ), the ion storage layer includes an oxidative discoloration material such as lithium nickel oxide (LiNiO _x ). However, the electrochromic device having the above configuration has a disadvantage in that the color change efficiency is not good and the switching time is slow.

The present application may include copper nitride (CuN _x ) in the ion storage layer to improve discoloration efficiency and switching time. Copper nitride (CuN _x ) not only has excellent thin film deposition property but also can sufficiently store and store charge even at a thickness of 100 nm or less, thereby reducing switching time between discoloration and discoloration of the device.

In one example, as the copper nitride (CuN _x ), a copper nitride having a mass ratio of copper to nitrogen of 0.01 ≦ N / Cu ≦ 0.3 may be used. More specifically, copper nitride (CuN _x ) in the range 0.05 ≦ N / Cu ≦ 0.20 may be used. When the mass ratio of N / Cu exceeds 0.2, it may be difficult to manufacture an ion storage layer because the copper nitride thin film is thermodynamically unstable, and when the mass ratio is less than 0.05, it may be difficult to implement the transparent thin film due to the predominant metal properties. have.

In one example, the ion storage layer may have a resistance of less than 1,000 ohm / sq. When the resistance value is within the above range, the electrical properties of the ion storage layer may be improved to contribute to increasing the response speed and lowering the switching time.

For the ion storage layer containing copper nitride (CuN _x ), in order to impart light transmitting characteristics, that is, transparent properties, it is preferable to form the thickness of the ion storage layer to 150 nm or less. For example, the ion storage layer may be formed to 120 nm or less, 100 nm or less, 80 nm or less, or 50 nm or less. The lower limit of the thickness is not particularly limited, but may be formed in a range of 10 nm or more. The ion storage layer of the present application, in the above thickness range, not only can have sufficient ion storage capacity required for the oxidation and reduction reaction of the electrochromic material, but also has a constant light transmittance without discoloration or discoloration, and thus, the electrochromic layer. Coloration or decolorization of can be sufficiently reflected in the device without being distorted by the ion storage layer.

In one example, the upper limit of the transmittance of the ion storage layer to visible light may be 95% or less, 90% or less, or 80% or less, and the lower limit may be 60% or more, or 70% or more. In addition, the refractive index of the ion storage layer with respect to visible light may be 2.0 to 3.5.

The electrolyte layer may include ions involved in the electrochromic reaction, such as lithium ions (Li ⁺ ). The kind of electrolyte included in the electrolyte layer is not particularly limited, and may be a liquid electrolyte, a gel-polymer electrolyte, or an inorganic solid electrolyte.

In one example, when the electrolyte is a gel-polymer electrolyte, the electrolyte layer may include a cured product of a composition containing a carbonate compound and a lithium compound. Since the carbonate compound has a high dielectric constant, the conductivity of the ions provided by the lithium salt can be increased. For example, carbonate-based compounds such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylmethyl carbonate (EMC) may be used, but are not limited thereto. LiF, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiClO ₃ , LiAsF ₆ , LiSbF ₆ , LiAl0 ₄ , LiAlCl ₄ , LiNO ₃ , LiN (CN) ₂ , LiPF ₆ , Li (CF ₃ ) ₂ PF ₄ , Li (CF ₃ ) ₃ PF ₃ , Li (CF ₃ ) ₄ PF ₂ , Li (CF ₃ ) ₅ PF, Li (CF ₃ ) ₆ P, LiSO ₃ CF ₃ , LiSO ₃ C ₄ F ₉ , LiSO ₃ (CF ₂ ) ₇ CF ₃ , or LiN (SO ₂ CF ₃ ) ₂ , and the like, for example, but is not limited thereto.

In another example, when the electrolyte is an inorganic solid electrolyte, the electrolyte layer may include a lithium phosphorus oxynitride or lithium ion doped transition metal oxide, or Ta ₂ O _5, which is called Lithium Phosphorous Oxynitride (LIPON). It may include. Specifically, the electrolyte layer may be a solid electrolyte doped with lithium metal in transition metal oxides such as molybdenum (Mo), tantalum (Ta), zirconium (Zr), hafnium (Hf), and tungsten (W). In the case of the gel polymer, bubbles are generated as the charge / discharge cycle increases and durability thereof is decreased. However, when the inorganic solid electrolyte is used, bubbles are not generated, thereby increasing durability and lifespan of the device.

The electrolyte layer may have a thickness in the range of 30 μm to 200 μm, and transmittance of visible light may range from 70% to 95%.

The electrochromic device of the present application may further include a power source. For example, the power source may be electrically connected to the electrode layer through an external circuit. The apparatus or method for applying the voltage may be appropriately selected by those skilled in the art and is not particularly limited.

In one example, the power source may apply a coloring potential of 2V or less to the electrochromic device, and apply a discoloration potential of 3V or more. The discoloration potential may be less than 6V or less than 4V. In the present application, only the electrochromic layer is colored or decolorized according to the applied voltage, and the ion storage layer may have a range of light transmittance without coloring or decolorizing. More specifically, when a coloring potential having a positive sign (+) is applied to the layer including NiO _x , that is, the electrode layer on which the electrochromic layer is directly stacked, the electrochromic layer is colored while the electrolyte ions are released. During the time that the electrochromic layer is colored, the copper nitride (CuN _x ) may serve as an ion storage layer while maintaining transparency without discoloration. On the contrary, in order to decolorize the electrochromic device, it is necessary to apply a decolorization potential having a negative sign to the electrode layer on which the electrochromic layer including NiO _x is directly stacked to a size of 3 V or more. If the coloration potential exceeds 2V size, the copper nitride (CuN _x ) is discolored, and it is difficult to play a role as an ion storage layer sufficiently. If the discoloration potential is less than 3V size, the color change of the electrochromic layer does not occur. When a voltage in the above range is applied, irrespective of the color decolorization reaction of the electrochromic layer, the ion storage layer can maintain a transmittance in the range of 60% to 80% with respect to visible light without large change in optical properties.

In another example of the present application, the present application relates to a method of manufacturing an electrochromic device. More specifically, the manufacturing method includes the steps of providing a copper nitride (CuNx) layer having a mass ratio of copper to nitrogen on one electrode layer in a range of 0.05 ≦ N / Cu ≦ 0.20, and nickel oxide on the other electrode layer. It may include providing a (NiO _X ) layer. As described above, the copper nitride (CuN _x ) layer may be used as an ion storage layer in the electrochromic device of the present application, and the nickel oxide (NiO _x ) layer may be used as an electrochromic layer. The configuration or other properties of the electrode layer, ion storage layer and electrochromic layer are the same as mentioned above.

The method of providing each said layer is not specifically limited, A well-known method can be used. For example, any one of deposition, spin coating, dip coating, screen printing, gravure coating, sol-gel, or slot die coating can be used. Each layer can be provided by. In the case of deposition, the deposition may be performed by physical vapor deposition (PVD) or chemical vapor deposition (CVD). Usable physical vapor deposition methods include sputtering, e-beam evaporation, thermal evaporation, laser molecular beam epitaxy (L-MBE) or pulsed laser deposition ( Pulsed Laser Deposition (PLD), etc., and examples thereof include Chemical Chemical Vapor Deposition (Thermal Chemical Vapor Deposition), Plasma-Enhanced Chemical Vapor Deposition (PECVD), and Photo Chemical Vapor Deposition (Light). Chemical Vapor Deposition, Laser Chemical Vapor Deposition, Metal-Organic Chemical Vapor Deposition (MOCVD), or Hydride Vapor Phase Epitaxy (HVPE). May be, but is not limited thereto.

In one example, the copper nitride (CuN _x ) layer may be deposited on one surface of the electrode layer by a sputtering method. More specifically, approximately 30 to 60 nm thick Cu target is formed, in a chamber having a 5 mTorr to 60 mTorr process pressure, a power of 100 W to 300 W is applied, and nitrogen (N ₂ ) gas is Through a process of supplying argon (Ar) gas at a flow rate of 15 sccm to 45 sccm at a flow rate of sccm to 25 sccm, a copper nitride (CuN _X ) layer may be provided on the electrode layer. At this time, the nitrogen partial pressure of the gas supplied into the chamber may be 40% or more, but is not particularly limited.

The manufacturing method of the present application may further include providing an electrolyte layer on one surface of the copper nitride (CuN _X ) layer or the nickel oxide (NiO _X ) layer. The kind of electrolyte that can be used for the electrolyte layer is the same as mentioned above.

The present application including the novel ion storage layer material can provide an electrochromic device that is not only excellent in thin film productivity but also improved in color change efficiency and color change rate.

1 is a schematic cross-sectional view of a general electrochromic device.

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

Experimental Example  1: Measurement of Optical and Driving Characteristics of Half-Cell

For the half-cell manufactured as described below, the driving and optical characteristics of each cell were measured at 25 ° C. using potentiostat equipment (Princeton Applied Research, PMC-1000) and UV-vis spectrometer equipment (Solidspec 3700). . 2V was applied as the coloring potential and 3.5V was applied as the discoloration potential. At this time, the size of each specimen used was consistent with 2.0 cm X 10 cm = 20 cm ² . The results are shown in Table 1 below.

Example

Preparation of Working Electrode: Electrodechromic layer formed of nickel oxide (NiO _x ) was deposited to 300 nm thickness using DC sputter method on ITO electrode, which is a transparent conductive oxide, and a working electrode comprising a first electrode and an electrochromic layer Was prepared.

Preparation of counter electrode: A formed ion storage layer containing copper nitride (CuN _x ) is deposited to a thickness of 30 nm on a transparent conductive oxide ITO electrode by using a DC sputter method, and includes a second electrode and an ion storage layer. A working electrode was prepared.

Comparative example  One

As in the above embodiment, except that a 300 nm thick tungsten oxide (WO _x ) layer is used as the electrochromic layer and a 300 nm thick nickel oxide (NiO _x ) layer is used as the ion storage layer. An electrochromic layer and an ion storage layer were prepared on the ITO electrode by using a DC sputter method.

Comparison of Optical and Driving Characteristics of Half-Cell Half-cell: working electrode containing an electrochromic layer Half-cell: counter electrode including ion storage layer Measure
Item TCO sheet resistance
(Ω / □) Charge
(mC) ΔT (%) Time (s)
Col. / Ble. TCO sheet resistance Charge
(mC) ΔT (%) Time (s)
Col. / Ble. Example 30 200 40 30/30 30 50 - - Comparative example 30 600 60 60/30 30 200 40 30/30 TCO sheet resistance: sheet resistance of ITO electrode
ΔT: Difference in transmittance during coloring and decolorization of each electrode
Time (s) Col. : Time taken for the electrode to transition from bleaching to coloring. It can be measured by the time required to have 80% transmittance relative to the transmittance of the fully colored state.
Time (s) Ble. : Time taken for the electrode to transition from a colored state to a bleaching state. It can be measured by the time required to have a transmittance of 80% relative to the transmittance of a completely bleached state.

As shown in Table 1, the ion storage layer included in the counter electrode of the present application, unlike the ion storage layer of the comparative example, it can be seen that there is no change in transmittance. This is because in the case of nickel oxide (NiO _x ) included in the comparative example ion storage layer, coloring and decolorization occur according to the applied voltage, whereas copper nitride (CuN _x ) included in the example ion storage layer does not color and decolorize. Means.

Experimental Example  2: Measurement of Optical and Driving Characteristics of Full-Cell

The working electrode and the counter electrode prepared in Examples and Comparative Examples, respectively, were bonded together via a gel polymer electrolyte prepared from a mixture of propylene carbonate (PC) and LiClO ₄ to prepare an electrochromic device. For the manufactured electrochromic device, optical and driving characteristics were measured using the same apparatus as Experimental Example 1. The results are shown in Table 2 below.

Comparison of Optical and Driving Characteristics of Full-Cell Electrochromic Device (Full Cell) ΔT (%) Coloring Time (s) Bleaching Time (s) Charge amount (mC) Example 40 9 5 60 Comparative example 50 36 13 250 ΔT: Difference in transmittance during coloring and decolorization of the entire device
Bleaching Time (s): The time taken when the electrochromic device is bleached in the colored state by the electrochromic layer. It can be measured by the time required to have a transmittance of 80% relative to the transmittance of a completely bleached state.
Coloring Time (s): The time required when the electrochromic device is colored in the bleaching state by the electrochromic layer. It can be measured by the time required to have 80% transmittance relative to the transmittance of the fully colored state.

As shown in Table 2, it can be seen that the charge amount of the entire electrochromic device composed of the working electrode and the counter electrode is larger than that of the comparative example. However, in the case of the coloration efficiency (coloration efficiency = ΔT / amount of charge) which can be represented by the change in the transmittance with respect to the amount of charge, it can be seen that the device of the embodiment is significantly higher than that of the comparative device. Furthermore, it can be seen that the device of the example has a switching time shortened by 50% or more of the comparative example.

Claims (19)

An electrochromic device comprising two oppositely disposed electrode layers, an electrochromic layer, an ion storage layer, and an electrolyte layer, the electrochromic layer comprising nickel oxide (NiO _x ), and the ion storage layer being copper nitride (CuN _x ) an electrochromic device comprising:
The electrochromic device further comprises a power source, wherein the electrochromic device has a color potential of 2 V or less, and a discoloration potential of 3 V or more.
The electrochromic device of claim 1, wherein the copper nitride (CuN _x ) satisfies a mass ratio in a range of 0.05 ≦ N / Cu ≦ 0.20.
The electrochromic device of claim 1, wherein the ion storage layer has a resistance of 1,000 ohm / sq or less.
The electrochromic device of claim 1, wherein the ion storage layer has a thickness in a range of 10 nm to 150 nm and a refractive index of visible light ranges from 2.0 to 3.5.
The electrochromic device of claim 2, wherein a transmission of visible light of the ion storage layer is in a range of 60% to 80%.
The electrochromic device of claim 1, wherein the electrochromic layer has a thickness in the range of 10 nm to 450 nm.
The electrochromic device according to claim 1, wherein the electrochromic layer has a transmittance of 20% to 50% for visible light when colored and 50% to 75% for visible light when decolored.
The electrochromic device of claim 1, wherein the electrolyte layer has a thickness of 30 μm to 200 μm and a light transmittance of visible light in a range of 70% to 95%.
The electrochromic device of claim 1, wherein the electrolyte layer comprises any one of a liquid electrolyte, a gel-polymer electrolyte, and an inorganic solid electrolyte.
The electrochromic device of claim 9, wherein the electrolyte is an inorganic solid electrolyte containing LiPON or Ta ₂ O ₅ .
The electrochromic device according to claim 9, wherein the electrolyte is a gel-polymer electrolyte formed from a cured product of a mixture containing a carbonate compound and a lithium compound.
The method of claim 11, wherein the carbonate-based compound is at least one compound selected from the group consisting of PC (propylene carbonate), EC (ethylene carbonate), DMC (dimethyl carbonate), DEC (diethyl carbonate) and EMC (ethylmethyl carbonate) Electrochromic device.
The method of claim 11, wherein the lithium compound is LiF, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiClO ₃ , LiAsF ₆ , LiSbF ₆ , LiAl0 ₄ , LiAlCl ₄ , LiNO ₃ , LiN (CN) ₂ , LiPF ₆ , Li (CF ₃ ) ₂ PF ₄ , Li (CF ₃ ) ₃ PF ₃ , Li (CF ₃ ) ₄ PF ₂ , Li (CF ₃ ) ₅ PF, Li (CF ₃ ) ₆ P, LiSO ₃ CF ₃ , LiSO ₃ At least one electrochromic device selected from C ₄ F ₉ , LiSO ₃ (CF ₂ ) ₇ CF ₃ , and LiN (SO ₂ CF ₃ ) ₂ .
The electrode layer of claim 1, wherein the electrode layer is formed of indium tin oxide (ITO), fluor doped tin oxide (FTO), aluminum doped zinc oxide (AZO), gallium doped zinc oxide (GZO), antimony doped tin oxide (ATO), or IZO (IZO). At least one transparent conductive compound selected from the group consisting of Indium doped Zinc Oxide), Niobium doped Titanium Oxide (NTO), ZnO, Oxide / Metal / Oxide (OMO) and CTO; Conductive polymers; Silver nanowires; And electrochromic device comprising any one of a metal mesh (Metal mesh).
The electrochromic device of claim 14, wherein the electrode layer has a thickness in a range of 1 nm to 1 μm, and transmittance of visible light is in a range of 70% to 95%.
delete Providing a copper nitride (CuNx) layer having a mass ratio of copper to nitrogen on the one electrode layer in a range of 0.05 ≦ N / Cu ≦ 0.20; And
It is a method of manufacturing an electrochromic device comprising the step of providing a nickel oxide (NiO _X ) layer on the other electrode layer,
The electrochromic device further comprises a power source, wherein the color potential of the electrochromic device is 2V or less in size, and the discoloration potential is 3V or more in size.
The method of claim 17, wherein the copper nitride (CuNx) layer or the nickel oxide (NiO _X ) layer is deposited, spin coated, dip coated, screen printed, gravure coated, or sol gel. A method of manufacturing an electrochromic device provided by any one of a gel method or a slot die coating.
18. The method of claim 17, further comprising providing an electrolyte layer on one surface of the copper nitride (CuNx) layer or nickel oxide (NiO _X ) layer, wherein the electrolyte layer is a liquid electrolyte, a gel-polymer electrolyte, or an inorganic solid. Method of manufacturing an electrochromic device comprising any one of an electrolyte.

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