WO2018199570A1

WO2018199570A1 - Light-transmissive film and electrochromic element comprising same

Info

Publication number: WO2018199570A1
Application number: PCT/KR2018/004672
Authority: WO
Inventors: 김용찬; 김기환
Original assignee: 주식회사 엘지화학
Priority date: 2017-04-24
Filing date: 2018-04-23
Publication date: 2018-11-01

Abstract

The present application relates to a light-transmissive film and an element comprising same. The film has light transmissivity, enables reversible chromism in accordance with an applied voltage and has excellent durability within a chromism driving voltage range.

Description

Light transmitting film and electrochromic device comprising the same

Cross Citation with Related Applications

This application claims the benefit of priority based on Korean Patent Application No. 10-2017-0052047 dated April 24, 2017 and Korean Patent Application No. 10-2018-0045418 dated April 19, 2018, the corresponding Korean patent All content disclosed in the literature of the application is included as part of this specification.

Field of technology

The present application relates to a light transmitting film and an electrochromic device including the same.

Electrochromic refers to a phenomenon in which the optical properties of the electrochromic material are changed by a reversible electrochemical oxidation or reduction reaction, and the device using the phenomenon is called an electrochromic device. In general, the change in the optical properties of the device can be realized through the color change of the layer or film containing the electrochromic material. For example, in the case of using WO ₃ which is almost colorless and transparent as an electrochromic material, a reduction reaction occurs when electrolyte ions and electrons are moved by voltage application, and the color of the layer or film including the electrochromic material becomes blue. It is colored. In contrast, when an oxidation reaction occurs in the layer or film, the layer or film is discolored to its original transparent state. In order for such discoloration to be fully realized in the device, not only the electrochromic layer or film in the discolored state, but also other layer or film configurations laminated together must have sufficient transparency (transmittance).

One object of the present application is to provide a light transmissive film that can be used in an electrochromic device.

Another object of the present application is to provide a light transmissive film capable of reversible discoloration depending on the voltage applied.

Still another object of the present application is to provide a light transmissive film for electrochromic device having excellent durability.

Still another object of the present application is to provide an electrochromic device including a transmissive film capable of reversible discoloration according to an applied voltage.

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

In one example of the present application, the present application relates to a light transmissive film. In the present application, the term “transmittance” may mean a case where the optical characteristic such as color change occurring in the electrochromic device is transparent enough to clearly recognize, and there is no external factor such as, for example, potential application. In the state (that is, the decoloring state described below), it may mean that the light transmittance of the film itself is at least 60% or more. More specifically, the lower limit of light transmittance of the light transmitting film of the present application may be 60% or more, 70% or more, or 75% or more, and the upper limit of the light transmittance may be 95% or less, 90% or less, or 85% or less. Unless otherwise specified, "light" in the present application may mean visible light in the wavelength range of 380 nm to 780 nm, and more specifically, visible light in the 550 nm wavelength. In addition, the transmittance can be measured using a known haze meter (HM).

The light transmissive film may include an oxynitride. In one example, the light transmissive film may be an oxynitride having one layer or film form or a laminate of an oxynitride having a layer or film form and another layer or film configuration. In this application, oxynitride is used differently from oxide or nitride.

In one example, the oxynitride may include two or more metals selected from Ti, Nb, Mo, Ta, and W.

In another example, the oxynitride of the light transmissive film may include Mo and Ti at the same time. In this regard, nitrides, oxides or oxynitrides containing only Mo are poor in adhesion to adjacent thin films, and nitrides, oxides or oxynitrides containing only Ti are poor in durability, such as decomposing upon application of potential. In particular, nitrides or oxynitrides containing any one of the metals listed above, such as Ti alone or Mo only, are for example 40% or less, 35% or less or 30% or less, even when no potential is applied. Since it has low light transmittance, such as having a visible light transmittance of, it is not suitable for use as an electrochromic film member requiring transparency when bleached. In addition, when using a film having a low transmittance at the time of decolorization as described above, for example, the difference in the transmittance at the time of coloration and the transmittance at the time of decolorization, such as the difference in the apparent optical properties of the coloration and decolorization required in the electrochromic device. Difficult to show

In one example, the oxynitride may be represented by the following formula (1).

[Formula 1]

Mo _a Ti _b O _x N _y

In Formula 1, a means an element content ratio of Mo, b means an element content ratio of Ti, x means an element content ratio of O, y means an element content ratio of N, a> 0, b> 0, x> 0, y> 0, 0.5 <a / b <4.0, and 0.005 <y / x <0.02. The term "element content ratio" in the present application may be atomic%, and may be measured by X-ray photoelectron spectroscopy (XPS). When the element content ratio (a / b) is satisfied, a film excellent in adhesion as well as durability in other layer configurations may be provided. When the element content ratio (y / x) is satisfied, the film may have a light transmittance of 60% or more. In particular, when the element content ratio (y / x) is not satisfied, the film has very low transparency (translucency), such as having a visible light transmittance of 40% or less or 35% or less. It cannot be used as an element for an element.

In one example, the light transmissive film may be a variable transmittance film that transmits light when a predetermined voltage is applied. The permeability variable properties result from the reduction discoloration properties of the oxynitrides described above. Specifically, the oxynitride included in the film has a light transmittance close to colorless in an intact state without an electrochemical reaction, but when a predetermined voltage is applied, discoloration, ie, coloration, occurs at a predetermined level or more with a reduction reaction with the electrolyte ions. Can be That is, the oxynitride is a reducing discoloration material. When the said translucent film is colored, the light transmittance falls to less than 60%. In summary, the film is an electrochromic transmittance variable film having a light transmittance of 60% or more when decoloring (or discoloring) and having a light transmittance of less than 60% when coloring.

In one example, the light transmissive film can be colored under voltage application conditions of -2V or less, for example -2.5V or less or -3V or less. That is, the colored level of the light transmissive film may be 2 V, 2.5 V or 3 V. In the present application, the term “colored level” refers to an electrochemical reaction caused by a transmissive film or a predetermined voltage applied to a half-cell including the film and the conductive layer, and as a result, the translucent film is colored. As described above, the transmittance of the film may be reduced, such as “minimum size (absolute value)” of a voltage that may cause coloration of the film. Since the coloring level, i.e., the minimum magnitude (absolute value) of the voltage causing coloring, serves as a kind of barrier for coloring, virtually no coloring occurs when an electric potential of a value smaller than the magnitude (absolute value) is applied. (Fine coloring may not be recognized by the user or may not be sufficient to be recognized). The coloring level of a light transmissive film can change to some extent according to a specific structure in 2 V or more range. When colored, the light transmissive film may have a color of (dark) gray or black color. Considering that the coloring level of oxides including any one of known color change materials, for example, Ti, Nb, Mo, Ta, and W, is about 1V, the light-transmitting film of the present application may be said to have excellent durability against high voltage. Can be.

Regarding the coloring level, the upper limit of the voltage magnitude (absolute value) applied for coloring of the film is not particularly limited, but may be, for example, 6 V or less. If it exceeds 6V, the light transmissive film, or another structure adjacent thereto, may deteriorate.

In one example, the thickness of the light transmissive film may be 150 nm or less. For example, the light transmissive film may have a thickness of 140 nm or less, 130 nm or less, or 120 nm or less. When the upper limit of the thickness is exceeded, the insertion or desorption of electrolyte ions may be lowered and the discoloration rate may be lowered. The lower limit of the thickness of the light transmissive film is not particularly limited, but may be, for example, 10 nm or more, 20 nm or more, or 30 nm or more. If it is less than 10 nm, the film stability is not good.

In one example, the light refractive index of the light transmitting film may be in the range of 1.5 to 3.0 or 1.8 to 2.8. When the visible light refractive index is in the above range, the light-transmitting film may implement visibility with respect to the appropriate transparency and optical properties change.

The method for forming the light transmissive film is not particularly limited. For example, on the premise of satisfying the above configuration, a known deposition method such as sputter deposition can be used in forming the light transmitting film.

In yet another example of the present application, the present application relates to an electrochromic device. The device may include an electrode layer, a light transmitting film, and an electrolyte (layer). The form in which the element includes an electrode layer, a light transmitting film, and an electrolyte (layer) is not particularly limited. For example, the device may sequentially include an electrode layer, a light transmitting film, and an electrolyte (layer).

The light transmissive film used for the electrochromic device may have the same configuration as mentioned above. Since the translucent film which has the said structure can have a visible light transmittance of 60% or more, it is suitable as a film for electrochromic elements. Further, as described above, since it can be colored when a predetermined voltage is applied, it can also be used as a so-called electrochromic layer. Specifically, the light-transmitting film may have a transmittance of 60% or more by itself when decolorized, that is, uncolored, and when colored, transmittance of less than 60%, for example, 45% or less, 30, while the transmittance becomes low. It can have a transmittance of less than or equal to 20%. In one example, the light transmissive film may have a light transmittance difference of 20% or more or 30% or more during coloring and decolorization.

Although not particularly limited, in addition to the light transmissive film, other components used together with the electrochromic device may also have a visible light transmittance of 60% or more, more specifically in the range of 60% to 95%. In one example, the electrochromic device may have a light transmittance difference of 10% or more, 20% or more, or 30% or more in coloration and decolorization.

The electrode layer may include a conductive compound, metal mesh, or OMO (oxide / metal / oxide).

In one example, as the transparent conductive compound used in the electrode layer, ITO (Indium Tin Oxide), In ₂ O ₃ (indium oxide), IGO (indium galium 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), NTO (Niobium doped Titanium Oxide), ZnO (zink oxide), or CTO (Cesium Tungsten Oxide) For example. However, the materials listed above are not limited to the material of the transparent conductive compound.

In one example, the metal mesh used for the electrode layer may include Ag, Cu, Al, Mg, Au, Pt, W, Mo, Ti, Ni, or an alloy thereof, and may have a lattice form. However, the materials usable for the metal mesh are not limited to the metal materials listed above.

In one example, the electrode layer may comprise oxide / metal / oxide (OMO). Since the OMO has a lower surface resistance than the transparent conductive oxide represented by ITO, it is possible to improve the electrical properties of the electrochromic device by reducing the color change rate.

The OMO may include a top layer, a bottom layer, and a metal layer provided between the two layers. In the present application, the upper layer may mean a layer located relatively farther from the translucent film among the layers constituting the OMO.

In one example, the top and bottom layers of an OMO electrode include Sb, Ba, Ga, Ge, Hf, In, La, Se, Si, Ta, Se, Ti, V, Y, Zn, Zr or oxides of these alloys. can do. The type of each metal oxide included in the upper layer and the lower layer may be the same or different.

In one example, the thickness of the top layer may range from 10 nm to 120 nm or from 20 nm to 100 nm. In addition, the visible light refractive index of the upper layer may be in the range of 1.0 to 3.0 or 1.2 to 2.8. When having a refractive index and a thickness in the above range, an appropriate level of optical properties can be imparted to the electrode layer and the device.

In one example, the thickness of the lower layer may range from 10 nm to 100 nm or from 20 nm to 80 nm. In addition, the visible light refractive index of the lower layer may be in the range of 1.3 to 2.7 or 1.5 to 2.5. When having a refractive index and a thickness in the above range, an appropriate level of optical properties can be imparted to the electrode layer and the device.

In one example, the metal layer included in the OMO electrode may include a low resistance metal material. Although not particularly limited, for example, one or more of Ag, Cu, Zn, Au, Pd, and alloys thereof may be included in the metal layer.

In one example, the metal layer may have a thickness in the range of 3 nm to 30 nm or in the range of 5 nm to 20 nm. In addition, the metal layer may have a visible light refractive index of 1 or less or 0.5 or less. When having a refractive index and a thickness in the above range, an appropriate level of optical properties can be imparted to the electrode layer and the device.

Although not particularly limited, the electrode layer of the above configuration may have a thickness of 50 nm to 400 nm or less. The light transmittance can be appropriately implemented within the thickness range.

In one example, the device may include another electrode layer. In this case, the electrode layer may be referred to as first and second electrode layers according to positions relative to other configurations. For example, the device may sequentially include a first electrode layer, an electrolyte layer, the light transmissive film, and a second electrode layer. The configuration of each electrode layer is the same as mentioned above.

The electrolyte layer may be configured to provide electrolyte ions involved in the electrochromic reaction. Electrolyte ions may be monovalent cations, such as H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , or Cs ⁺ , which are inserted into the light transmissive film and which may be involved in the discoloration reaction.

The kind of electrolyte is not particularly limited. For example, liquid electrolytes, gel polymer electrolytes or inorganic solid electrolytes can be used without limitation.

If the electrochromic film composition can include a compound capable of providing a monovalent cation such as H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , or Cs ⁺ , the composition of the specific compound used in the electrolyte layer Is not particularly limited. For example, the electrolyte may be LiClO ₄ , LiBF ₄ , LiAsF ₆ , or LiPF ₆ It may include a lithium salt compound, such as, or a sodium salt compound such as NaClO ₄ .

In another example, the electrolyte layer may include a carbonate compound as a solvent. Since a carbonate type compound has high dielectric constant, ionic conductivity can be improved. As a non-limiting example, a solvent such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC) or ethylmethyl carbonate (EMC) may be used as the carbonate-based compound.

In one example, when the electrolyte layer comprises a gel polymer electrolyte, the electrolyte layer may be polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polymethyl methacrylate ( Polymethyl methacrylate (PMMA), Polyvinyl chloride (PVC), Polyethylene oxide (PEO), Polypropylene oxide (PPO), Poly (vinylidene fluoride-hexafluoro fluoropropylene) ( Poly (vinylidene fluoride-hexafluoro propylene), PVdF-HFP), polyvinylacetate (Polyvinyl acetate, PVAc), polyoxyethylene (Polyoxyethylene, POE), polyamideimide (Polyamideimide, PAI) and the like may be included.

Although not particularly limited, the thickness of the electrolyte layer may range from 10 μm to 200 μm.

In one example, the electrochromic device of the present application may further include a second electrochromic layer. When the second electrochromic layer is included in the device, the device may further include a second electrochromic layer between the first electrode layer and the electrolyte. In this case, the electrochromic translucent film may be referred to as a first electrochromic layer.

The second electrochromic layer may have a color change characteristic different from that of the first electrochromic layer. That is, the second electrochromic layer may include an oxidative discoloring material that may be colored when oxidized. As such, when the color development (color change) characteristics of the color change material used in each of the first and second electrochromic layers are different, the second electrochromic layer is different from the first electrochromic layer during oxidation and reduction for electrochromic. You can set the charge balance of.

In one example, the oxidative discoloration material included in the second electrochromic layer, such as LiNiOx, IrO ₂ , NiO, V ₂ O ₅ , LixCoO ₂ _, Rh ₂ O ₃ or CrO ₃ , Cr, Mn, Fe, Oxides of Co, Ni, Rh, or Ir; Hydroxides of Cr, Mn, Fe, Co, Ni, Rh, or Ir; And prussian blue.

Although not particularly limited, the thickness of the second electrochromic layer may range from 50 nm to 450 nm.

In one example, the electrochromic device may further include a substrate. The substrate may be located on the outer side of the device, for example on the outer side of the first and / or second electrode layer.

The substrate may also have a visible light transmittance of 60% to 95%. If the transmittance | permeability of the said range is satisfied, the kind of base material used will not be restrict | limited in particular. For example glass or polymer resins can be used. More specifically, a polyester film such as polycarbonate (PC), polyethylene (phthalene naphthalate) (PEN) or polyethylene (ethylene terephthalate) (PET), an acrylic film such as poly (methyl methacrylate) (PMMA), or polyethylene (PE) Or a polyolefin film such as PP (polypropylene) may be used, but is not limited thereto.

In another example, the electrochromic device may further include a power source. The manner of electrically connecting the power source to the device is not particularly limited and may be appropriately made by those skilled in the art.

According to an example of the present application, a film having not only light transmittance but also reversible discoloration according to an applied voltage and excellent in resistance to high voltage may be provided.

1 is a graph showing a state in which the laminate of the present application Example 1 is driven without degradation in durability when a voltage of ± 5 V is applied.

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.

실험례Experimental Example 1: One: 산질화물층의Oxynitride layer 원소 함량과 그에 따른 투과율 비교 Comparison of Element Content and its Transmittance

실시예 1Example 1

Preparation of the laminate : ITO having a light transmittance of about 90% was formed on one surface of glass (galss) having a light transmittance of about 98%. Subsequently, an oxynitride (Mo _a Ti _b O _x N _y ) layer containing Mo and Ti was formed on the one surface of ITO (as opposed to the glass position) by sputter deposition to form a thickness of 30 nm (Preparation Example 1). Specifically, the weight percent ratio of the target of Mo and Ti was 1: 1, the deposition power was 100 W, the process pressure was deposited at 15 mTorr, and each flow rate of Ar, N ₂ and O ₂ was 30 sccm, 5 sccm, and 5 sccm.

Physical property measurement: The content ratio of each element of the oxynitride layer and the transmittance of the laminate were measured, and are shown in Table 1 below. Elemental content (atomic%) was measured by X-ray photoelectron spectroscopy (XPS), and transmittance was measured using a haze meter (solidspec 3700).

비교예 1Comparative Example 1

Nitrogen nitride layer was formed in the same manner as in Example 1, except that the flow rate of nitrogen was 10 sccm during deposition and the content ratio was changed as shown in Table 1 (Preparation Example 2).

비교예Comparative example 2 2

Nitrogen nitride layer was formed in the same manner as in Example 1, except that the flow rate of nitrogen was 15 sccm during deposition, and the content ratio was changed as shown in Table 1 (Preparation Example 3).

비교예Comparative example 3 3

An oxide layer was formed in the same manner as in Example 1 except that the flow rate of nitrogen was 0 sccm during deposition and the content ratio was changed as shown in Table 1 (Preparation Example 4).

TABLE 1

From Table 1, it can be inferred that the oxynitride layers of Comparative Examples 1 to 3 have very low transmittance, while the oxynitride layer of Example 1 has a transmittance of about 90%. Unlike the comparative example, the oxynitride or the light-transmitting laminate including the same used in Example 1 can be used as a member for the electrochromic device.

실험례Experimental Example 2: 변색 특성 확인 2: Confirm discoloration characteristics

실시예 2Example 2

The laminate prepared in Example 1 (glass / ITO / oxynitride (Mo _a Ti _b O _x N _y ) (half-cell) was immersed in an electrolyte containing LiClO ₄ (1M) and propylene carbonate (PC), 25 Coloring voltage of −3 V and decolorization voltage of +3 V were applied alternately at 50 ° C. for 50 seconds, respectively.The currents, transmittances, and discoloration times at the time of coloration and decolorization measured over time are as shown in Table 2. .

In addition, the above measurements were also performed for ± 4 V and ± 5 V, and the results are shown in Table 2.

TABLE 2

As shown in Table 2, it can be seen that the laminate including the light-transmitting film of the present application has a discoloration characteristic when a potential having a size of 3 V or more is applied.

On the other hand, Fig. 1 is a graph showing the state in which the laminate (electrochromic device) of Example 2 is driven when a driving potential of ± 5 V is applied. 1, it can be seen that the laminate including the light-transmitting film of the present application exhibits uniform cycle characteristics even when a relatively high driving potential is applied and operates without deterioration in durability.

Claims

A light transmissive film comprising an oxynitride containing two or more metals selected from Ti, Nb, Mo, Ta, and W, and having a light transmittance of 60% or more.
The translucent film of claim 1, wherein the oxynitride comprises Mo and Ti.
The light-transmissive film of claim 2, wherein the oxynitride is represented by Formula 1:

[Formula 1]

Mo a Ti b O x N y

(Where a means an element content ratio of Mo, b means an element content ratio of Ti, x means an element content ratio of O, y means an element content ratio of N, and a> 0 , b> 0, x> 0, y> 0, 0.5 <a / b <4.0, and 0.005 <y / x <0.02.)
The translucent film of claim 1, wherein the thickness is 150 nm or less.
The translucent film of claim 1, wherein the visible light refractive index is in the range of 1.5 to 3.0.
The translucent film of Claim 1 which has a coloring level of 2 V or more.
An electrode layer; The light transmitting film according to any one of claims 1 to 6; And an electrochromic device comprising an electrolyte layer.
The electrochromic device of claim 7, further comprising a first electrode layer, the electrolyte layer, the light transmissive film, and a second electrode layer.
The electrochromic device of claim 8, further comprising a second electrochromic layer between the first electrode layer and the electrolyte layer.
The electrochromic device of claim 9, wherein the second electrochromic layer comprises an oxidative discoloring material.