KR102397828B1 - Electrochromic device having improved discoloring performance and driving method for thereof - Google Patents

Abstract

The present invention relates to an electrochromic device that is discolored by external power supply and a method of driving the same. In the electrochromic device according to the present invention, a discoloration layer in which different discoloration materials are mixed is activated by external light, thereby changing a color change reaction rate It relates to an electrochromic device capable of improving the light transmittance range and preventing structural deterioration of the device during discoloration and discoloration.

Description

Electrochromic device having improved discoloring performance and driving method for thereof

The present invention relates to an electrochromic element that is discolored by external power supply and a driving method thereof, and more particularly, to a color-changing layer in which different color-changing materials are mixed, electrons generated by external light having a specific energy convert the color-changing material. The present invention relates to an electrochromic device capable of improving a color change reaction rate and a range of light transmittance during discoloration and preventing structural deterioration of the device by activation thereof and a driving method thereof.

Electrochromism is a phenomenon in which the color changes reversibly according to the direction of an electric field when a voltage is applied, and devices having this characteristic are called electrochromic devices. Electrochromic devices, including color-changing materials that change color due to the movement of electrons, are used to control light transmittance or reflectivity of architectural windows, automobile mirrors, goggles, etc. However, as it is known that it has an infrared blocking effect, the possibility of application as an energy-saving product is also receiving great attention.

In the electrochromic material, an electrode layer, an electrochromic layer, an electrolyte layer, and an ion storage layer are sequentially stacked between a transparent substrate at a predetermined interval, and the electrochromic layer is changed by external power supply. The power discoloration layer is discolored by oxidation and reduction reactions, and discoloration performance such as discoloration response speed or light transmittance range during discoloration is limited depending on the discoloration material used.

In addition, in order to activate the device after manufacturing the color-changing device, a charging process of injecting positive ions through one electrode by applying a high voltage is required. , there is a problem in that the structure of the color-changing material is collapsed and the durability and reliability of the device are lowered.

Republic of Korea Patent Publication No. 10-2006-0092362 (Title of the invention: electrochromic device and manufacturing method thereof)

The present invention has been devised to solve the above problems, and the present invention provides an electrochromic device capable of improving reaction speed and a light transmittance range during color change, and preventing structural deterioration of the device, and a method for driving the same. There is a purpose.

In order to achieve the above object, the present invention provides an electrochromic device in which an electrode layer is formed and an electrochromic layer, an electrolyte layer, and an ion storage layer are stacked between the opposing transparent substrates, wherein the electrochromic layer has different types of color change The materials are mixed, and external light having a predetermined wavelength and intensity is irradiated during initialization to generate electrons.

In the present invention, the electrochromic layer is formed by mixing color-changing materials having different color-changing reaction rates or light transmittance during color change.

In the present invention, the electrochromic layer is WO ₃ , TiO ₂ , MoO ₃ , viologen, two or more of PEDOT are mixed, or NiO, Ir(OH) ₂ , CoO ₂ , ITO Two or more are mixed and formed. At this time, TiO ₂ /WO ₃ is mixed in a ratio of 1/9 to 3/7.

In addition, the present invention provides a method of driving an electrochromic device for initializing the electrochromic device by irradiating external light, and then applying an external power to change the color of the electrochromic layer. At this time, external light is irradiated with ultraviolet or visible light at an intensity of 1,000 to 3,000 mJ.

According to the present invention, the color-changing layer formed by mixing different kinds of color-changing materials having different color-changing properties is activated by irradiating external light to improve the color-changing reaction rate and the light transmittance range during color change, and also by irradiating external light. By activating the discoloration layer, the initialization voltage of the device can be lowered, thereby improving the reliability and durability of the device.

1 is a configuration diagram illustrating an electrochromic device according to the present invention.
2 is a view schematically showing an electrochromic layer according to the present invention.
3 shows the light transmittance at the time of discoloration measured by applying an external power source after initialization by irradiating external light in an embodiment according to the present invention, and the light transmittance at the time of discoloration measured by applying an external power source without irradiating external light. This is a comparison graph.
4 is a graph comparing the discoloration rate of Examples according to the present invention and Comparative Examples.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiment of the present invention illustrated below may be modified in various other forms, and the scope of the present invention is not limited to the embodiment described below.

1 is a view showing the configuration of an electrochromic device according to the present invention. Referring to this, the electrochromic device according to the present invention includes electrode layers 120 and 160 and an electrochromic layer between opposing transparent substrates 110 and 170 at a predetermined interval. 130 , the electrolyte layer 140 , and the ion storage layer 150 are stacked.

The transparent substrates 110 and 170 may be made of transparent plastic or glass having a light transmittance of 95% or more so that sunlight is transmitted therein. As the transparent plastic, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polypropylene (PP), polyimide (PI), and triacetyl cellulose (TAC) may be used. The substrate layers 10 and 50 are formed to a thickness of 10 μm to 5 mm.

The electrode layers 120 and 160 are formed in the upper and lower transparent organs 110 and 170, respectively, and are formed of a transparent conductive material that allows electricity to flow without interfering with the transmission of light, ITO, ATO, FTO, IZO, ZnO, copper oxide, A metal oxide such as zinc oxide or titanium oxide may be used. The electrode layers 120 and 160 may be formed in the form of a thin film on the transparent substrates 110 and 170 through a known coating process such as sputtering, and are preferably formed to a thickness of 300 nm to 1,000 nm.

The electrochromic layer 130 is formed on the electrode layer 120 and is a layer that is discolored by the movement of electric charges or electrolyte ions that are injected by the power supplied. It can be done in any one of WO ₃ , TiO ₂ , MoO ₃ , viologen, PEDOT can be used as a reducing color change material, and NiO, Ir(OH) ₂ , CoO ₂ , ITO as an oxidation color change material. can be used

The electrochromic layer 130 may be formed by mixing different kinds of color-changing materials having different color-changing reaction rates or light transmittance ranges at the time of color change when formed of such a reducing or oxidizing color-changing material. That is, the electrochromic layer 130 may be formed by mixing two or more of the above-described WO ₃ , TiO ₂ , MoO ₃ , and viologen when implemented as a reduced color-chromic layer, and when implemented as an oxidation-colored layer, NiO, Ir(OH) ₂ , may be formed by mixing two or more of CoO ₂ . As described above, the electrochromic layer 130 of the present invention can satisfy the color change performance required for the color change device by mixing different color change materials.

For example, when the electrochromic layer 130 is formed by mixing TiO ₂ and WO ₃ , TiO ₂ has a relatively faster electron transfer rate than WO ₃ , and WO ₃ has relatively higher light transmittance when discolored than TiO ₂ . It has a wide range of features. Therefore, when TiO ₂ and WO ₃ are mixed in a certain ratio, the discoloration reaction rate and the light transmittance range at the time of discoloration can be improved together. For this, TiO ₂ /WO ₃ is preferably mixed in a ratio of 1/9 to 3/7. Do. Here, when the mixed TiO ₂ ratio is increased, the discoloration rate is improved, but there is a problem in that the light transmittance range is reduced.

In addition, the electrochromic layer 130 may have an activation effect by external light having a specific energy due to a difference in band gaps of different color-changing materials, as will be described later.

FIG. 2 shows an electrochromic layer 130 formed by mixing a first color-changing material 131 and a second color-changing material 132. A solution in which different color-changing materials are mixed is slotted using a roll-to-roll device. It may be coated on the transparent conductive substrate by coating, gravure coating, etc., and is preferably formed to a thickness of 100 nm to 900 nm.

The electrolyte layer 140 is a layer that provides an environment for movement of hydrogen ions or lithium ions for discoloration or decolorization of the electrochromic layer 130 , and a liquid polymer electrolyte that can be cured by UV irradiation may be used. The UV-curable resin may be composed by mixing a PEG-based or urethane-based oligomer, low molecular weight PEGDMe, PEGDA, and a photo or thermal initiator, and a liquid electrolyte in which an electrolyte salt is dissolved in a solvent is formed. In this case, as the solvent, EC, PC, DMC, DEC, EMC, etc. may be used singly or in combination, and the electrolyte salt may be a compound containing H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ . However, for example, LiClO ₄ , LiBF ₄ , LiAsF ₆ , or a lithium salt compound such as LiPF ₆ may be used singly or in combination. The electrolyte composed in this way is formed in a layered manner by gap-coated between the electrochromic layer 130 and the ion storage layer 150 with uniform spacing, and preferably is formed in a thickness of 100 μm to 500 μm.

The ion storage layer 150 is formed to balance charge with the electrochromic layer 130 during reversible oxidation and reduction reactions for color change of the electrochromic layer 130 . The ion storage layer 150 is formed to include a color change material having a color development characteristic different from that of the electrochromic layer 130 , that is, a color change material having complementary color development characteristics. The thickness of the ion storage layer 150 is formed according to the amount of charge of the electrochromic layer 130, and is preferably formed in a range of 100 nm to 2000 nm.

In this way, the electrodes 120, 160, the electrochromic layer 130, the electrolyte layer 140, and the ion storage layer 150 are stacked between the transparent substrates 110 and 170 to form the color-changing device 100, and the electrochromic layer ( 130) and the ion storage layer 150 is irradiated with external light to excite electrons.

The irradiated external light is irradiated to sufficiently excite electrons of the electrochromic layer 130 and the ion storage layer 150. In the case of the electrochromic layer 130 of the present invention, different color-changing materials are mixed and formed. Accordingly, light of a wavelength band capable of exciting electrons is irradiated according to the band gap of each color-changing material. For example, when TiO ₂ and WO ₃ are mixed, TiO ₂ bandgap is 3.1 to 3.94 eV, and light in the ultraviolet band (315 to 400 nm) can be irradiated, and it is visible to activate WO ₃ having a band gap of 2.4 eV. Light in the light band (400-700 nm) may be irradiated, and both TiO ₂ and WO ₃ may be activated by irradiating UV and visible light together.

And, external light is irradiated with an intensity of 1,000 to 3,000 mJ. If the intensity of external light exceeds 3,000 mJ, deterioration of the electrolyte may occur, and if it is less than 1,000 mJ, sufficient activity is not achieved in the thick electrochromic layer 130. there is no problem

As described above, when light that excites electrons of the first color-changing material 131 is irradiated to the electrochromic layer 130 in which the first color-changing material 131 and the second color-changing material 132 are mixed, some of the excited electrons are It reacts with monovalent cations (H+, Li+, etc.) inside the electrolyte, and the remainder of the excited electrons react with the second color-changing material 132 and then react with monovalent cations inside the electrolyte to be activated.

Therefore, a smooth discoloration reaction of the electrochromic layer 130 after initialization is possible, as well as 40 ~ compared to the initialization voltage when not activated due to a potential difference between the activated electrochromic layer 130 and the ion storage layer 150 Since initialization is possible even with a low voltage of 60%, the durability and reliability of the device can be improved without causing side reactions of the electrolyte and damage to the junction interface that occur when a high voltage is applied.

<Example>

An ITO electrode layer of 500 nm was formed on the surface of a pair of 10 μm thick polyethylene terephthalate (PET) transparent substrates, respectively. Then, a color-changing solution in which TiO ₂ /WO ₃ was mixed in 1/3 was prepared, and then coated to a thickness of 600 nm on any one of the transparent substrates on which the electrode layer was formed to form an electrochromic layer, and an ionic color-changing layer on the other transparent substrate. was formed. Then, a liquid electrolyte in which LiClO ₄ was dissolved in EC was prepared, and a liquid electrolyte was gap-coated between the electrochromic layer and the ion-chromic layer, and a pair of transparent substrates were laminated to manufacture a color-changing device.

<Comparative example>

It is the same as in Example except that the electrochromic layer was formed of WO ₃ .

<Measurement of light transmittance>

First, the device was initialized by irradiating UV light for 10 minutes in Example, then power was applied to measure light transmittance (red graph in FIG. 3 ), and then, power was applied without UV irradiation to measure light transmittance. (blue graph in FIG. 3). In this case, the light transmittance was measured using a UV/Vis-spectrometer.

As shown in FIG. 3 , when the electrochromic layer is activated by irradiating light, the visible light transmittance is 25 to 62%, whereas when the light is not irradiated, the visible light transmittance is 22 to 57%, When the device was activated by irradiation, the light transmittance range was wide.

<Measurement of discoloration speed>

After initializing the device by irradiating each of the Examples and Comparative Examples with ultraviolet light for 10 minutes, power was applied to measure the light transmittance (red graph in FIG. 4 - Example, blue graph - Comparative example). As shown in Figure 4, it can be seen that the Example is discolored faster than the Comparative Example.

These results show that the electrochromic layer of the embodiment formed by mixing TiO ₂ with a fast discoloration rate and WO ₃ with a wide light transmittance range is activated by light irradiation, and then power is applied to change color when the light transmittance is wide and fast discoloration rate. It can be seen that the color change performance is excellent even when a low initialization voltage is applied.

The present invention described above is not limited to the described embodiments, and it is apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. Accordingly, it should be said that such variations or modifications fall within the scope of the claims of the present invention.

110, 170: transparent substrate 120, 160: electrode layer
130: color-changing layer 131: first color-changing material
132: second color-changing material 140: electrolyte layer
150: ion storage layer

Claims (7)

In an electrochromic device in which an electrode layer is formed and an electrochromic layer, an electrolyte layer, and an ion storage layer are stacked between opposing transparent substrates,
The electrochromic layer is
WO ₃ , TiO ₂ , MoO ₃ , a single-layer structure formed including two or more reducing color change materials among viologen and PEDOT, or a single-layer structure formed including two or more oxidation color change materials among NiO, Ir(OH) ₂ and CoO ₂ has,
It is characterized in that the electrons are activated by irradiating external light of a wavelength that excites any one of the two or more color-changing materials or external light of a wavelength that respectively excites any two or more color-changing materials during initialization after manufacturing,
The two or more color-changing materials have different color-changing reaction rates or light transmittance ranges during color-changing, electrochromic devices. delete The method of claim 1,
The electrochromic layer is
WO ₃ , TiO ₂ , MoO ₃ , viologen, electrochromic device, characterized in that formed by mixing two or more of PEDOT. The method of claim 1,
The electrochromic layer is
In NiO, Ir(OH) ₂ , CoO ₂ An electrochromic device characterized in that two or more are mixed and formed. 4. The method of claim 3,
TiO ₂ /WO ₃ Electrochromic device, characterized in that mixed in a ratio of 1/9 to 3/7. An electrode layer is formed and an electrochromic layer, an electrolyte layer, and an ion storage layer are stacked between the opposing transparent substrates, and the electrochromic layer includes two or more reducing color change materials among WO ₃ , TiO ₂ , MoO ₃ , viologen and PEDOT. In the method for driving an electrochromic device having a single-layer structure formed, or a single-layer structure formed including two or more oxidation color change materials among NiO, Ir(OH) ₂ and CoO ₂ ,
an initialization step of activating electrons by irradiating external light having a wavelength to excite any one of the two or more color-changing materials or external light having a wavelength for exciting each of the two or more color-changing materials after the electrochromic device is manufactured; and
and discoloring the electrochromic layer by applying an external power to the electrochromic element after initialization,
The method for driving an electrochromic device, wherein the two or more color-changing materials have different color-changing reaction rates or light transmittance ranges during color change. 7. The method of claim 6,
The method for driving an electrochromic device, characterized in that the external light is irradiated with an intensity of 1,000 to 3,000 mJ with ultraviolet or visible light.

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