KR20170112379A - An Electrochromic Device - Google Patents

Abstract

The present application relates to an electrochromic device and a manufacturing method thereof. The present application, which includes a novel ion storage layer material, provides an electrochromic device having excellent durability and thin film productivity and improved discoloration rate compared to the prior art.

Description

[0001] An Electrochromic Device [

The present application relates to an electrochromic device. Specifically, the present application relates to an electrochromic device having improved color fading efficiency and switching time.

Electrochromism is a phenomenon in which optical properties such as color and light transmittance of an electrochromic active material are changed by electrochemical oxidation and reduction reactions. Electrochromic devices using such a phenomenon are attracting attention in various fields such as smart windows, smart mirrors, and electronic paper because they can be manufactured with a small area and have low power consumption.

1 is a cross-sectional view of a general electrochromic device. As shown in the figure, 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, 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, the outer surface of each of the electrodes 110 and 150 may further include a substrate formed of transparent glass or polymer resin.

In general, the electrochromic layer and / or the ion storage layer may contain an inorganic substance 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 ⁺ and Na ⁺ move between the electrochromic layer and the ion storage layer through the electrolyte layer, and at the same time, The oxidation / reduction reaction of the electrochromic material alternates and the coloring or bleaching of the electrochromic layer or the ion storage layer is performed as the electrochromic material is injected or separated from the electrochromic layer. Since the movement of the ionic material is presupposed in the change of the optical characteristic of the electrochromic device as described above, a predetermined time, that is, a switching time is required for discoloration, thereby improving the discoloration efficiency and reducing the discoloration time Technology is required.

An object of the present invention is to provide an electrochromic device excellent in discoloration efficiency and improved in discoloration rate.

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

These and other objects of the present application can be resolved by the present application, which is 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.

In one example, the electrode may be a transparent conductive oxide (TCO), a conductive polymer, a silver nanowire, or a metal mesh And a metal mesh. More specifically, it is possible to use a metal oxide such as ITO (indium tin oxide), FTO (fluoro-doped tin oxide), AZO (aluminum doped zinc oxide), GZO (gallium doped zinc oxide), ATO (antimony doped tin oxide), IZO , Niobium doped titanium oxide (NTO), ZnO, oxide / metal / oxide (OMO), or CTO may be used as the electrode material. 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 any limitation. For example, an electrode layer can be provided by forming an electrode material containing 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 in the range of 1 nm to 1 占 퐉. 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 implementation.

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

The electrochromic layer may include an electrochromic material whose color changes depending on an electrical signal. Examples of usable electrochromic materials include conductive polymers, organic coloring materials and / or inorganic coloring materials. As the conductive polymer, polypyrrole, polyaniline, polypyridine, polyindole, polycarbazole, or the like can be used. As the organic coloring material, materials such as viologen, anthraquinone, phenothiazine and the like can be used. no.

The electrochromic layer may include an inorganic discoloring substance. For example, an oxide of at least one oxide of Ti, Nb, Mo, Ta, W, V, Cr, Mn, Fe, Co, Ni, Rh and Ir may be contained as an inorganic discoloring substance. More specifically, the electrochromic layer of the present application may contain nickel oxide (NiO _x ) as an oxidative discoloring substance, and the nickel oxide may be deep brown by an oxidation reaction depending on a voltage applied to the electrode layer Can be colored.

In the above reaction, when the discoloring substance contained in the electrochromic layer is discolored, the electrochromic device transmits incident light. When the discolored material is colored, the amount of incident light is reduced, and the optical characteristic of the electrochromic device can be changed. The coloring and decoloring reactions may occur alternately depending on the polarity of the applied voltage or the direction of the 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% with respect to visible light upon coloring and a transmittance of 50% to 75% with respect to visible light upon decolorization.

The ion storage layer may mean a layer that can be inserted or removed from the charge particles necessary for the oxidation-reduction reaction of the electrochromic layer, and can participate in the discoloration reaction. In the prior art, a complementary electrochromic material was used for each of the electrochromic layer and the ion storage layer in consideration of the role of the ion storage layer. For example, when the electrochromic layer contains a reducing discoloration substance such as tungsten oxide (WO _x ), the ion storage layer contains an oxidative discoloring substance such as lithium nickel oxide (LiNiO _x ). However, the electrochromic device having the above-described structure has a disadvantage that the coloring efficiency is poor and the switching time is slow.

The present application may include copper nitride (CuN _x ) in the ion storage layer to improve the discoloration efficiency and the switching time. Copper nitride (CuN _x ) not only has excellent thin film deposition properties but also can sufficiently store and store charges even at a thickness of 100 nm or less, so that the switching time required for discoloration and discoloration of the device can be reduced.

In one example, as the copper nitride (CuN _x ), copper nitride having a mass ratio of copper to nitrogen in the range of 0.01? N / Cu? 0.3 may be used. More specifically, copper nitride (CuN _x ) having a range of 0.05? N / Cu? 0.20 may be used. If the mass ratio of N / Cu exceeds 0.2, it may be difficult to produce an ion storage layer because the copper nitride thin film is thermodynamically unstable. If the mass ratio is less than 0.05, the metal characteristic is dominant, have.

In one example, the ion storage layer may have a resistance of less than or equal to 1,000 ohm / sq. When the resistance value is within the above range, it is possible to improve the electrical characteristics of the ion storage layer, thereby increasing the response speed and reducing the switching time.

For the ion storage layer containing copper nitride (CuN _x ), it is preferable that the thickness of the ion storage layer is 150 nm or less in order to impart the light transmission property, that is, the transparent property. For example, the ion storage layer can 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 in the range of 10 nm or more. The ion storage layer of the present application can not only 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, Can be sufficiently reflected on the device without being distorted by the ion storage layer.

In one example, the transmittance of the ion storage layer to visible light may be up to 95%, 90%, or 80%, and the lower limit may be 60% or more, or 70% or more. 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 ion (Li ^< ^{+ &} gt ^; ). The type of the electrolyte contained 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 comprise a cured product of a composition comprising 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 compounds such as PC (propylene carbonate), EC (ethylene carbonate), DMC (dimethyl carbonate), DEC (diethyl carbonate) and EMC (ethylmethyl carbonate) may be used. Lithium compounds are 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.

In another example, when the electrolyte is an inorganic solid electrolyte, the electrolyte layer may be made of a lithium phosphorus oxynitride or a lithium ion-doped transition metal oxide called LIPON (Lithium Phosphorous Oxynitride), or Ta ₂ O ₅ . Specifically, the electrolyte layer may be a solid electrolyte in which lithium metal is doped in a transition metal oxide such as molybdenum (Mo), tantalum (Ta), zirconium (Zr), hafnium (Hf), and tungsten (W). In the case of the gel polymer, bubbles are generated and durability is lowered as the charge / discharge cycle is increased. On the other hand, when the inorganic solid electrolyte is used, the durability and lifetime of the device can be increased because no bubbles are generated.

The electrolyte layer may have a thickness in the range of 30 [mu] m to 200 [mu] m, and the transmittance to 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 an electrode layer through an external circuit. Apparatuses and methods for applying a voltage can be appropriately selected by a person skilled in the art and are not particularly limited.

In one example, the power source can apply a coloring potential of 2 V or less to the electrochromic device, and can apply a decoloring potential of 3 V or more. The decoloring potential may be 6 V or less or 4 V or less. In the case of this application, only the electrochromic layer is colored or discolored depending on the applied voltage, and the ion storage layer can have a certain range of light transmittance without coloring or discoloring. More specifically, when a colored potential having positive (+) sign is applied to a layer containing NiO _x , that is, an electrode layer directly stacked with an electrochromic layer, with a size of 2 V or less, electrolyte ions are desorbed, And the copper nitride (CuN _x ) can function as an ion storage layer while maintaining transparency without discoloration, for a duration time of coloring the electrochromic layer. On the other hand, in order for the electrochromic device to decolorize, the decoloring potential having negative (-) sign should be applied to the electrode layer directly stacked with the electrochromic layer containing NiO _x at a size of 3V or more. When the coloring potential exceeds 2V, it causes discoloration of copper nitride (CuN _x ), so that it is difficult to sufficiently function as an ion storage layer. When the decoloring potential is less than 3V, discoloration of the electrochromic layer does not occur. When the voltage in the above range is applied, irrespective of the color 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 characteristics.

In another example of this 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 and nitrogen in a range of 0.05? N / Cu? 0.20 on one electrode layer; (NiO < _X >) layer. As described above, the copper nitride (CuN _x ) layer can be used as an ion storage layer in the present electrochromic device, and the nickel oxide (NiO _x ) layer can be used as the electrochromic layer. The structure and other properties of the electrode layer, ion storage layer and electrochromic layer are the same as those mentioned above.

The method of forming each layer is not particularly limited, and a known method can be used. For example, any one of a deposition method, a spin coating method, a dip coating method, a screen printing method, a gravure coating method, a sol-Gel method, or a slot die coating method Each layer may be provided. The deposition can be performed by physical vapor deposition (PVD) or chemical vapor deposition (CVD). Examples of the physical vapor deposition method that can be used include a sputtering method, an E-beam evaporation method, a thermal evaporation method, a laser molecular beam epitaxy (L-MBE) method, or a pulsed laser deposition method Pulsed Laser Deposition (PLD)). Examples of the chemical vapor deposition method include a thermal chemical vapor deposition method, a plasma enhanced chemical vapor deposition (PECVD) method, a light chemical vapor deposition method (Light Chemical Vapor Deposition) Chemical vapor deposition (CVD), Laser Chemical Vapor Deposition, Metal-Organic Chemical Vapor Deposition (MOCVD), or Hydride Vapor Phase Epitaxy (HVPE) But is not limited thereto.

In one example, a copper nitride (CuN _x ) layer can be deposited on one side of the electrode layer by a sputtering process. More specifically, a Cu target having a thickness of approximately 30 to 60 nm is formed and a power of 100 W to 300 W is applied in a chamber having a process pressure of 5 mTorr to 60 mTorr, and a nitrogen (N ₂ ) gas is introduced into the chamber 5 (CuN _x ) layer can be provided on the electrode layer by supplying argon (Ar) gas at a flow rate of 15 sccm to 25 sccm at a flow rate of 15 sccm to 45 sccm. 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 the step of providing an electrolyte layer on one side of the copper nitride (CuN _x ) layer or the nickel oxide (NiO _x ) layer. The kind of the electrolyte that can be used for the electrolyte layer is the same as mentioned above.

The present application including a novel ion storage layer material can provide an electrochromic device having not only excellent thin film productivity but also improved color fading efficiency and discoloration rate.

Fig. 1 schematically shows a cross-sectional view of a general electrochromic device.

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 embodiments described below.

Experimental Example  1: Measurement of optical characteristics and driving characteristics of half-cell

The driving characteristics and the optical characteristics of each cell were measured at a temperature of 25 ° C using a potentiostat apparatus (Princeton Applied Research, PMC-1000) and a UV-vis spectrometer apparatus (Solidspec 3700) . A voltage of 2 V was applied before the coloring, and a voltage of 3.5 V was applied before the coloring. At this time, the size of each specimen used was matched to 2.0 cm × 10 cm = 20 cm ² . The results are shown in Table 1 below.

Example

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

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

Comparative Example  One

(WO _x ) layer of 300 nm thickness was used as the electrochromic layer, and a nickel oxide (NiO _x ) layer of 300 nm thickness was used as the ion storage layer. An electrochromic layer and an ion storage layer were provided on the ITO electrode using a DC sputtering method.

Comparison of optical and driving characteristics of half-cell Half-cell: Working electrode containing electrochromic layer Half-cell: a counter electrode including an ion storage layer Measure
Item TCO surface resistance
(Ω / □) Charge quantity
(mC) ΔT (%) Time (s)
Col. / Ble. TCO surface resistance Charge quantity
(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 surface resistance: sheet resistance value of ITO electrode
ΔT: Difference in transmittance between coloring and decoloring of each electrode
Time (s) Col. : The time it takes for the electrode to change from bleaching to coloring. Can be measured as the time taken to have an 80% transmittance versus a completely colored state.
Time (s) Ble. : The time it takes for the electrode to change from a coloring to a bleaching state. Can be measured as the time taken to have an 80% transmittance versus a completely discolored state.

As shown in Table 1, unlike the ion storage layer of the comparative example, the ion storage layer included in the counter electrode of the present application shows no change in transmittance. In the case of nickel oxide (NiO _x ) contained in the comparative example ion storage layer, coloration and discoloration occur depending on the applied voltage, whereas the copper nitride (CuN _x ) contained in the ion storage layer of the embodiment does not cause discoloration or discoloration .

Experimental Example  2: Measurement of optical characteristics and driving characteristics of full-cell

The working electrode and the counter electrode prepared in each of the above Examples and Comparative Examples were cemented through a gel polymer electrolyte prepared from a mixture of PC (propylene carbonate) and LiClO ₄ to prepare an electrochromic device. Optical and drive characteristics of the electrochromic device were measured using the same apparatus as in Experiment 1. The results are shown in Table 2 below.

Comparison of optical characteristics and driving characteristics of full-cell Electrochromic devices (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 between coloring and decolorization of all devices
Bleaching Time (s): Time required when the electrochromic device is bleached by the electrochromic layer in the coloring state. Can be measured as the time taken to have an 80% transmittance versus a completely discolored state.
Coloring Time (s): The time required when the electrochromic device is colored by the electrochromic layer in the bleaching state. Can be measured as the time taken to have an 80% transmittance versus a completely 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 in the comparative example. However, in the case of the discoloration efficiency (coloration efficiency = DELTA T / charge amount) which can be represented by the change in the transmittance with respect to the charge amount, it can be confirmed that the elements of the embodiment are much higher than those of the comparative example. Further, it is confirmed that the device of the embodiment has a switching time shortened by 50% or more in the comparative example.

Claims (19)

Wherein the electrochromic layer comprises nickel oxide (NiO _x ), the ion storage layer is made of copper nitride (CuN), and the electrochromic layer _x ). &_lt; / RTI >
The electrochromic device according to claim 1, wherein the copper nitride (CuN _x ) satisfies a mass ratio of 0.05? N / Cu? 0.20.
The electrochromic device according to claim 1, wherein the ion storage layer has a resistance of 1,000 ohm / sq or less.
The electrochromic device according to claim 1, wherein the ion storage layer has a thickness in a range of 10 nm to 150 nm and a refractive index in a range of 2.0 to 3.5 with respect to visible light.
The electrochromic device according to claim 2, wherein a transmittance of the ion storage layer to visible light ranges from 60% to 80%.
The electrochromic device according to claim 1, wherein the electrochromic layer has a thickness ranging from 10 nm to 450 nm.
The electrochromic device according to claim 1, wherein the electrochromic layer has a transmittance of visible light of 20% to 50% and a transmittance of visible light of 50% to 75%.
The electrochromic device according to claim 1, wherein the electrolyte layer has a thickness of 30 탆 to 200 탆, and a light transmittance to visible light ranges from 70% to 95%.
The electrochromic device according to claim 1, wherein the electrolyte layer comprises any one of a liquid electrolyte, a gel-type polymer electrolyte, and an inorganic solid electrolyte.
The electrochromic device according to 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-type 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 compound is at least one compound selected from the group consisting of propylene carbonate (EC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and 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 Wherein the electrochromic device is at least one selected from the group consisting of C ₄ F ₉ , LiSO ₃ (CF ₂ ) ₇ CF ₃ , and LiN (SO ₂ CF ₃ ) ₂ .
The method according to claim 1, wherein the electrode layer is formed of a material selected from the group consisting of indium tin oxide (ITO), fluoro-doped tin oxide (FTO), aluminum oxide doped zinc oxide (AZO), antimony doped tin oxide (ATO) At least one transparent conductive compound selected from the group consisting of Indium-doped Zinc Oxide (ITO), Niobium-doped Titanium Oxide (NTO), ZnO, Oxide / Metal / Oxide (OMO) Conductive polymer; Silver nanowires; And a metal mesh. The electrochromic device according to claim 1,
15. The electrochromic device according to claim 14, wherein the electrode layer has a thickness in the range of 1 nm to 1 占 퐉 and a transmittance to visible light ranges from 70% to 95%.
The electrochromic device according to claim 1, wherein the electrochromic device further comprises a power source, the absolute value of the coloring potential of the electrochromic device is 2 V or less, and the absolute value of the decoloring potential is 3 V or more.
Providing a copper nitride (CuNx) layer having a copper / nitrogen mass ratio in the range of 0.05? N / Cu? 0.20 on one electrode layer; And
And forming a nickel oxide (NiO _x ) layer on the other electrode layer.
Article according to claim 17, (NiO _X) wherein the nitride copper (CuNx) layer or a nickel oxide layer is deposited (deposition), spin-coating (spin coating), dip coating (dip coating), screen printing, gravure coating, sol-gel (sol -Gel method, or a slot die coating method.
18. The method of claim 17, further comprising a step of providing an electrolyte layer to a surface of the nitride copper (CuNx) layer or a nickel oxide (NiO _X) layer, the electrolyte layer is a liquid electrolyte, a gel-type polymer electrolyte or an inorganic solid Wherein the electrochromic device comprises an electrolyte.

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