KR102056599B1 - An Electrochromic Device - Google Patents

Abstract

The present application relates to an electrochromic device and a method of manufacturing the same. The present application using 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 or lithium nickel oxide 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 in 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, and thus a technique for reducing the color change time 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 (Aluminum 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 electrode layer thickness is not particularly limited, but for the purpose of low resistance, the electrode layer may have a thickness of 800 nm or less, 700 nm or less, or 500 nm or less.

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.

In one example, the electrochromic layer may include one or more oxides of oxides of Ti, Nb, Mo, Ta, W, V, Cr, Mn, Fe, Co, Ni, Rh, and Ir as an inorganic color change material. have. More specifically, TiO _{2 ,} Nb ₂ O ₅ , MoO ₃ , Ta ₂ O ₅ , WO _x , V ₂ O _{5 ,} CrO _{3 ,} Li _x CoO _{2 ,} NiO, LiNiO _x , Rh ₂ O _3, IrO _2, etc. This may be an inorganic discoloration material that can be used, but is not limited thereto.

More specifically, the electrochromic layer of the present application may include tungsten oxide (WO _x ) as an electrochromic material. The tungsten oxide (WO _x ) may be colored or decolorized through the following reaction. In the scheme below, M may be an electrolyte ion such as H ⁺ , Li ⁺ , or Na ⁺ .

[Scheme]

WO ₃ (discoloration: ^{clear) + xe - + xM + ⇔} M x WO 3 ( colors: blue)

In the above reaction, when the electrochromic layer is decolorized, the electrochromic device transmits incident light, and when the electrochromic layer is colored, the optical characteristic of the electrochromic device may be changed while the amount of incident light is reduced. The coloration and decolorization reaction may take place alternately depending on the polarity (or direction of current flow) of the applied voltage.

In one example, the electrochromic layer may have a transmittance of 10% to 50% for visible light when colored and a range of 45% to 85% for visible light when decolored.

In one example, the electrochromic layer may have a thickness of 50 nm to 400 nm. When the thickness is less than 50 nm, it is difficult to sufficiently cause a reaction for discoloration, and when the thickness exceeds 400 nm, an electrochromic device of a thin film cannot be provided.

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 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 (CuN _x ) thin film is thermodynamically unstable, and when the mass ratio is less than 0.05, the metal properties prevail to implement a transparent thin film. It can be difficult to do.

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 including the copper nitride (CuN _x ), the thickness of the ion storage layer may be 150 nm or less in order to impart light transmitting characteristics, that is, transparent properties. 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 lithium phosphorus oxynitride or lithium ion doped transition metal oxide, or Ta ₂ O _5, which is called LIPON (Lithium Phosphorous Oxynitride). 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 supply may apply a coloring potential of 2V or less to the electrochromic device, and may similarly apply a discoloration potential of 2V or less. 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 negative sign (-) is applied to the layer including WO _x , that is, the electrode layer on which the electrochromic layer is directly stacked, the electrochromic layer is colored while lithium ions are inserted. During the time that the electrochromic layer is colored, copper nitride (CuN _x ) included in the ion storage layer may function as an ion storage layer while maintaining transparency without discoloration. On the contrary, in order to decolorize the electrochromic device, a decolorization potential having a positive sign must be applied to the electrode layer on which the electrochromic layer including WO _x is stacked. When the magnitude of the coloring and discoloring voltage exceeds 2V, discoloration of copper nitride (CuN _x ) is caused, and thus it is difficult to sufficiently serve as an ion storage layer. 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 a 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 comprises the steps of providing a copper nitride (CuN _x ) layer having a mass ratio of copper to nitrogen on one electrode layer in the range 0.05 ≦ N / Cu ≦ 0.20, and tungsten on the other electrode layer Providing an oxide (WO _x ) layer. As described above, the copper nitride (CuN _x ) layer may be used as an ion storage layer in the present electrochromic device, and the tungsten oxide (WO _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 evaporation ( 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, and 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 and argon A copper nitride (CuN _x ) layer may be provided on the electrode layer through a process of supplying (Ar) gas at a flow rate of 5 to 25 sccm and 15 to 45 sccm, respectively. At this time, the partial pressure of nitrogen in 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 a copper nitride (CuN _x ) layer or a tungsten oxide layer. The type of electrolyte that can be used in the electrolyte layer is as mentioned above.

The present application including a novel ion storage layer material can provide an electrochromic device that not only has excellent thin film productivity, but also has improved color discoloration efficiency, thereby reducing discoloration speed.

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 voltage was applied to the colored and decolorized potentials, respectively. 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 tungsten oxide (WO _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

Except that a 100 nm thick LiNiOx layer was used as the ion storage layer, the electrochromic layer and the ion storage layer were prepared on a different 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 30 600 60 60/30 30 50 - - Comparative Example 1 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 means that in the case of lithium nickel oxide included in the comparative ion storage layer, coloring and decolorization occur according to the applied voltage, whereas copper nitride included in the example ion storage layer does not occur coloring and decolorization.

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 30 11 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 layer is bleached in the colored state. 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 taken when the electrochromic layer is colored in the bleaching state. 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 embodiment has a switching time shortened by 50% or more compared with the comparative example.

Claims (19)

A first electrode; An electrochromic layer on the first electrode and in contact with the first electrode; An electrolyte layer disposed on the electrochromic layer and in contact with the electrochromic layer; An ion storage layer disposed on the electrolyte layer and in contact with the electrolyte layer; And a second electrode disposed on the ion storage layer and in contact with the ion storage layer.
The electrochromic layer includes tungsten oxide (WO _x ), which is a reducing color change material, and the ion storage layer includes copper nitride (CuN _x ),
The copper nitride (CuN _x ) satisfies a mass ratio in the range of 0.05 ≦ N / Cu ≦ 0.20,
The ion storage layer is an electrochromic device that does not color and decolorize.
delete 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 1, 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 of 50 nm to 400 nm.
The electrochromic device according to claim 1, wherein the electrochromic layer has a transmittance of 10% to 50% for visible light when colored and 45% to 85% 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 of 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 electrochromic compound of claim 11, wherein the carbonate-based compound is a compound selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylmethyl carbonate (EMC). 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 An electrochromic device selected from C ₄ F ₉ , LiSO ₃ (CF ₂ ) ₇ CF ₃ , and LiN (SO ₂ CF ₃ ) ₂ .
The method of claim 1, wherein the electrode layer comprises: a transparent conductive compound (TCO); 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%.
The electrochromic device of claim 1, wherein the electrochromic device further includes a power source, and the colored and decolorized potentials of the electrochromic device have a size of 2 V or less.
Providing a copper nitride (CuN _x ) 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
A method of manufacturing an electrochromic device according to claim 1, comprising the step of providing a tungsten oxide layer (WO _x ) on another electrode layer.
The method of claim 17, wherein the copper nitride (CuN _x ) layer or the tungsten oxide (WO _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 sol-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 a lithium nickel oxide (LiNiO _x ) layer, wherein the electrolyte layer is a liquid electrolyte, a gel-polymer electrolyte, or an inorganic. Method of manufacturing an electrochromic device comprising any one of a solid electrolyte.

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