JP5258640B2 - All-solid-state electrochromic device - Google Patents

Description

  The present invention relates to an electrochromic device, and more particularly to an all-solid-type electrochromic device in which all components are made of solid.

Currently, liquid crystal display elements (LCD), organic electroluminescence elements (organic EL elements), and the like are widely used as display elements.
These display elements change color only while a voltage is applied and can display characters and images, but display requires a relatively high voltage, and thus consumes a lot of power. In some cases, it was necessary to frequently replace the operating battery. Therefore, it is difficult to replace the battery (battery) at any time in a structure in which an interior part such as an IC chip or a display element is sealed with an adhesive, such as an IC card, and a liquid crystal display element or an organic The EL element was unsuitable.

  Therefore, depending on the application, an electrochromic element (EC element) has attracted attention as a display element that replaces a liquid crystal display element or an organic EL element. This EC element has a relatively low voltage required for operation, and has a property (memory property) that allows the display state to be stopped simply by blocking the movement of electrons and maintaining the oxidation-reduction state. In order to maintain the display state Since no power is required, there is an advantage of low power consumption.

  Such EC elements include, for example, an electrochromic layer that changes absorption or reflection during oxidation or reduction, and ion conduction that functions as an electrolyte and allows ions to pass through while blocking electron current. A five-layer structure comprising a layer (solid electrolyte layer), a counter electrode that functions as a layer that accumulates ions when the device is decolored, and two conductive layers that have the function of applying a potential to the EC element Have been disclosed (for example, see Patent Document 1).

JP 2006-235632 A

  In the EC element disclosed in Patent Document 1, although the electrochromic layer and the ion conductive layer are formed by the sputtering method, after all the above layers are laminated, in a temperature range of about 280 to 500 ° C., Since the device is heat-treated for about 10 to 30 minutes, each layer including the ion conductive layer is crystallized. Thus, when the ion conductive layer is crystallized, in the EC element, it is difficult for the coloring layer to be doped / undoped with lithium ions. At low current and low voltage, not only the contrast of the EC element is low, but also repetitive. There was a problem of insufficient color development.

  The present invention has been made in view of the above circumstances, and comprises an chromic layer provided on a paper substrate, and has an all-solid-state electrochromic element that repeatedly develops color at low current and low voltage with high contrast. The purpose is to provide.

  The all-solid-state electrochromic device of the present invention includes a first base material, an electrode layer, a first ion supply layer, a second ion supply layer, and a solid electrolyte layer that are sequentially laminated on one surface of the first base material. An all-solid-type electrochromic device comprising a coloring layer, a transparent electrode layer, and a second substrate, wherein the first ion supply layer is made of spinel-type lithium manganate, and the second ion supply layer is It consists of lithium iron phosphate with an olivine structure.

  The first substrate and / or the second substrate is preferably a paper substrate.

  The all-solid-state electrochromic device of the present invention includes a first base material, an electrode layer, a first ion supply layer, a second ion supply layer, and a solid electrolyte layer that are sequentially laminated on one surface of the first base material. An all-solid-type electrochromic device comprising a coloring layer, a transparent electrode layer, and a second substrate, wherein the first ion supply layer is made of spinel-type lithium manganate, and the second ion supply layer is Since it is made of lithium iron phosphate with an olivine structure, the ionic conductivity of the ion supply layer composed of the first ion supply layer and the second ion supply layer is stable and does not change. Even if a chromic layer consisting of an electrode layer, a first ion supply layer, a second ion supply layer, a solid electrolyte layer, a color developing layer and a transparent electrode layer is provided between the first substrate and the second substrate, low current, low voltage With high contrast It is possible to repeatedly coloring.

It is a schematic sectional drawing which shows one Embodiment of the all-solid-state electrochromic element of this invention.

An embodiment of the all solid-state electrochromic device of the present invention will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

"All-solid-state electrochromic device"
FIG. 1 is a schematic cross-sectional view showing an embodiment of the all solid-state electrochromic device of the present invention.
The all-solid-state electrochromic element 10 of this embodiment includes a first substrate 11, an electrode layer 12, a first ion supply layer 13, and a second ion that are sequentially stacked on one surface 11 a of the first substrate 11. The supply layer 14, the solid electrolyte layer 15, the coloring layer 16, the transparent electrode layer 17, and the second base material 18 are roughly configured.
The electrode layer 12 is a back electrode, and the transparent electrode layer 17 is a surface electrode.

  The “all solid-type electrochromic device” is one in which all components are made of solid without including liquid in the components such as the electrolyte.

As the first base material 11 and the second base material 18, at least on the surface layer portion thereof, a woven fabric, a non-woven fabric, a mat, paper or the like made of inorganic fibers such as glass fiber and alumina fiber, or a combination thereof, polyester fiber Woven fabrics, non-woven fabrics, mats, paper, etc. made of organic fibers such as polyamide fibers, or combinations thereof, or composite substrates formed by impregnating them with a resin varnish, polyamide-based resin substrates, polyester-based materials Resin substrate, polyolefin resin substrate, polyimide resin substrate, ethylene-vinyl alcohol copolymer substrate, polyvinyl alcohol resin substrate, polyvinyl chloride resin substrate, polyvinylidene chloride resin substrate, polystyrene Resin base material, polycarbonate resin base material, acrylonitrile butadiene styrene copolymer resin base material Plastic base materials such as polyethersulfone-based resin base materials, or mat processing, corona discharge processing, plasma processing, ultraviolet irradiation processing, electron beam irradiation processing, flame plasma processing, ozone processing, or various types of easy adhesion processing. It is selected from known ones such as those subjected to surface treatment. In addition, as paper, high-quality paper, coated paper, art paper, cast coated paper, recycled paper, impregnated paper, dust-free paper, water-resistant paper, fluorescent paper, and a circuit was formed on these paper base materials using a conductive paint or the like. Examples thereof include a conductive paper base material.
Among these, as the first base material 11 and the second base material 18, an electrically insulating film or sheet made of polyethylene terephthalate or polyimide, or a paper base material is preferably used.

Examples of the electrode layer 12 and the transparent electrode layer 17 include an amorphous electrode layer composed of tin-doped indium oxide (ITO), zinc oxide (ZnO), tin oxide (SnO ₂ ), and the like.
Since the electrode layer 12 is not provided at a position facing the coloring layer 15, the visible light transmittance does not become a problem, and may not be transparent.

The thickness of the electrode layer 12 is not particularly limited, but is appropriately adjusted in the range of 5 nm to 3000 nm according to the intended conductivity and visible light transmittance.
The thickness of the transparent electrode layer 17 is not particularly limited, but is appropriately adjusted in the range of 5 nm to 5000 nm according to the intended conductivity, visible light transmittance, and the like.

The first ion supply layer 13 is an amorphous layer composed of lithium manganate (LiMn ₂ O ₄ ) having a spinel structure.
Here, the spinel is an equiaxed octahedral crystal made of magnesium and aluminum oxide (MgAl ₂ O ₄ ), and the spinel structure is the same structure as this crystal.

  Although the thickness of the 1st ion supply layer 13 is not specifically limited, It is suitably adjusted in the range of 5 nm-5000 nm according to the operating voltage, contrast, response speed, visible light transmittance, etc. of the target element.

The second ion supply layer 14 is an amorphous layer composed of lithium iron phosphate (LiFePO ₄ ) having an olivine structure.
Here, the olivine structure is an orthorhombic crystal having symmetry of the space group P _mnb . In the olivine lithium iron phosphate, oxygen (O) forms a hexagonal close-packed structure, lithium (Li) and iron (Fe) occupy a hexacoordinate octahedron, and phosphorus (P) is tetracoordinated. The structure occupies the tetrahedron.

  The thickness of the second ion supply layer 14 is not particularly limited, but is appropriately adjusted in the range of 5 nm to 5000 nm according to the operating voltage, contrast, response speed, visible light transmittance, and the like of the target element.

Examples of the solid electrolyte layer 15 include an amorphous ion conductive transparent layer.
The substance constituting the amorphous ion conductive transparent layer has a general formula: Li _w A _x B _y O _z (where A is one or two selected from La and Si, and B is selected from Ti and P) 1 or 2 types, 0 <w ≦ 4, 0 ≦ x ≦ 1, 0 <y ≦ 1, 0 ≦ z ≦ 12) 1 type or 2 selected from lithium composite oxides More than species.
Specific examples of the lithium composite oxide include La _0.57 Li _0.26 TiO ₃ , Li _3.5 Si _0.5 P _0.5 O ₄ , and Li ₃ PO ₄ .

  If the solid electrolyte layer 15 is composed of these amorphous lithium composite oxides, the yield of the all-solid-state electrochromic element 10 is higher than when the solid electrolyte layer 15 is composed of a crystalline substance. At the same time, the all-solid-state electrochromic element 10 can be colored with a lower current and a lower voltage.

  The thickness of the solid electrolyte layer 15 is not particularly limited, but is appropriately adjusted in the range of 5 nm to 5000 nm according to the operating voltage, contrast, response speed, visible light transmittance, and the like of the target element.

Examples of the coloring layer 16 include amorphous coloring layers made of WO ₃ , lithium (Li) ion-doped amorphous Li _y WO _3-x , sodium (Na) ion-doped amorphous Na _x WO _{3, and the} like.

  The thickness of the color forming layer 16 is not particularly limited, and is appropriately adjusted in the range of 5 nm to 5000 nm according to the operating voltage, contrast, response speed, visible light transmittance, and the like of the target element.

  According to this all-solid-state electrochromic device 10, the first ion supply layer 13 is made of spinel lithium manganate and the second ion supply layer 14 is made of olivine lithium iron phosphate. Since the ion conductivity of the ion supply layer composed of the layer 13 and the second ion supply layer 14 is stable and does not change, an electrode layer is provided between the first base material 11 and the second base material 18 made of a paper base material. 12, even if a chromic layer comprising the first ion supply layer 13, the second ion supply layer 14, the solid electrolyte layer 15, the color forming layer 16 and the transparent electrode layer 17 is provided, the contrast is reduced at a low current and a low voltage. High color can be developed repeatedly. Specifically, at a voltage of 3 V and a current of 0.01 mA to 1 mA, a response speed (coloring speed) of 1 second to 3 seconds and a time during which the display state can be stopped (memory time) of 72 hours or more can be realized.

"Method for manufacturing all-solid-state electrochromic device"
Next, with reference to FIG. 1, the manufacturing method of the all-solid-state electrochromic element of this embodiment is demonstrated.
In this embodiment, a pulse laser deposition method (Pulsed Laser Deposition, PLD method) is used to form an electrode layer 12, a first coloring layer 13, a second coloring layer 14, a solid electrolyte layer 15 on the first substrate 11. A chromic layer composed of the ion supply layer 16 and the transparent electrode layer 17 is formed.

(Formation of electrode layer 12)
First, the 1st base material 11 is arrange | positioned in a vacuum chamber, and this 1st base material 11 is maintained at normal temperature.
Next, a target for the electrode layer 12 such as tin-doped indium oxide, zinc oxide, or tin oxide is disposed at a predetermined distance from the outermost surface of the one surface 11a of the first base material 11, and the oxygen atmosphere pressure in the vacuum chamber is set to 0. Hold at 1 Pa to 10 Pa.
Next, the target is irradiated with laser light having an energy density of 0.1 J / cm ^{2 to} 100 J / cm ² , and the amorphous electrode layer 12 is laminated on the one surface 11 a of the first substrate 11.

(Formation of the first ion supply layer 13)
Next, a target for the first ion supply layer 13 made of lithium manganate having a spinel structure (LiMn ₂ O ₄ ) is disposed at a predetermined distance from the outermost surface of the electrode layer 12 provided on the first substrate 11. The oxygen atmosphere pressure in the vacuum chamber is maintained at 0.1 Pa to 50 Pa.
Next, the target is irradiated with laser light having an energy density of 0.1 J / cm ^{2 to} 100 J / cm ² to stack the amorphous first ion supply layer 13 on the electrode layer 12.

(Formation of the second ion supply layer 14)
Next, the target for the second ion supply layer 14 made of lithium iron phosphate (LiFePO ₄ ) having an olivine structure is placed at a predetermined distance from the outermost surface of the first ion supply layer 13 provided on the first substrate 11. And maintaining the oxygen atmosphere pressure in the vacuum chamber at 0.1 Pa to 50 Pa.
Next, the target is irradiated with laser light having an energy density of 0.1 J / cm ^{2 to} 100 J / cm ² to stack the amorphous second ion supply layer 14 on the first ion supply layer 13.

(Formation of solid electrolyte layer 15)
A target for the solid electrolyte layer 15 made of perovskite-type La _{2 / 3-x} Li _3x TiO ₃ is disposed at a predetermined distance from the outermost surface of the second ion supply layer 14 provided on the first substrate 11. The oxygen atmosphere pressure in the vacuum chamber is maintained at 0.1 Pa to 50 Pa.
Next, the target is irradiated with laser light having an energy density of 0.1 J / cm ^{2 to} 100 J / cm ² to stack the amorphous solid electrolyte layer 15 on the second ion supply layer 14.

Specific examples of the lithium composite oxide include perovskite type La _{2 / 3-x} Li _3x TiO ₃ and γ-Li ₃ PO ₄ type Li _3.6 Si _0.6 P _0.4 O _4. Is mentioned.

(Formation of coloring layer 16)
WO ₃ , lithium ion-doped amorphous Li _y WO _3-x , sodium ion-doped amorphous Na _x WO _3, etc. at a predetermined distance from the outermost surface of the solid electrolyte layer 15 provided on the first substrate 11. The target for the coloring layer 16 is disposed, and the oxygen atmosphere pressure in the vacuum chamber is maintained at 0.1 Pa to 30 Pa.
Next, the target is irradiated with laser light having an energy density of 0.1 J / cm ^{2 to} 100 J / cm ² , and the amorphous coloring layer 16 is laminated on the solid electrolyte layer 15.

(Formation of transparent electrode layer 17)
A target for the transparent electrode layer 17 such as tin-doped indium oxide, zinc oxide, tin oxide or the like is disposed at a predetermined distance from the outermost surface of the color forming layer 16 provided on the first substrate 11, and the oxygen atmosphere pressure in the vacuum chamber Is maintained at 0.1 Pa to 10 Pa.
Next, the target is irradiated with laser light having an energy density of 0.1 J / cm ^{2 to} 100 J / cm ² , and an amorphous transparent electrode layer 17 is laminated on the color forming layer 16.

  Next, the second base material 18 is stuck on the transparent electrode layer 17 to obtain the all solid-state electrochromic element 10.

As described above, the electrode layer 12, the first ion supply layer 13, the second ion supply layer 14, and the solid electrolyte are formed on the first substrate 11 by using a pulsed laser deposition (PLD method). A chromic layer composed of the layer 15, the color forming layer 16 and the transparent electrode layer 17 is formed, spinel-structured lithium manganate (LiMn ₂ O ₄ ) is used as the target for the first ion supply layer 13, and the second ion supply layer 14 If olivine-structured lithium iron phosphate (LiFePO ₄ ) is used as a target, all layers (electrode layer 12, ion supply layer 13, solid electrolyte layer 14, color development) are also formed on the first substrate 11 made of a paper substrate. The all-solid-type electrochromic device 10 in which the layer 15 and the transparent electrode layer 16) are amorphous can be manufactured at a low temperature. That. Therefore, since the step of heat-treating the all-solid-state electrochromic element 10 is not necessary, the solid electrolyte layer 14 is not crystallized, and the all-solid-state electrochromic element 10 is stable at a low current and a low voltage. Function.

Further, in the formation of the solid electrolyte layer 15, if a pulse laser deposition method is used, an amorphous solid electrolyte layer having an impurity content of 0.2% can be formed. The all solid-state electrochromic element 10 provided with the amorphous solid electrolyte 15 has a yield of about 99%.
On the other hand, if a sputtering method is used in forming the solid electrolyte layer, a crystallized solid electrolyte layer having an impurity content of 1% is formed. The all-solid-type electrochromic device provided with this crystallized solid electrolyte has a yield of about 90%. This is presumably due to the fact that in the sputtering method, the oxygen atmosphere pressure in the vacuum chamber must be 2 Pa or less, so that the proportion of impurities present in the vacuum chamber is higher than in the pulse laser deposition method.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to a following example.

"Example"
(Formation of electrode layer)
An electrode layer target made of tin-doped indium oxide is disposed at a predetermined distance from the outermost surface of one surface of the first substrate by arranging the first substrate in a vacuum chamber and maintaining the first substrate at room temperature. The oxygen atmosphere pressure in the vacuum chamber is maintained at 2 Pa, the target is irradiated with laser light having an energy density of 7.1 J / cm ² , and an amorphous electrode layer is formed on one surface of the first substrate. Were laminated.

(Formation of the first ion supply layer)
Next, a target for the first ion supply layer made of spinel lithium manganate (LiMn ₂ O ₄ ) is disposed at a predetermined distance from the outermost surface of the electrode layer provided on the first substrate, and the vacuum chamber Was maintained at 30 Pa, and the target was irradiated with laser light having an energy density of 3 J / cm ² to laminate an amorphous first ion supply layer on the electrode layer.

(Formation of second ion supply layer)
Next, a target for the second ion supply layer made of lithium iron phosphate having an olivine structure (LiFePO ₄ ) is disposed at a predetermined distance from the outermost surface of the first ion supply layer provided on the first substrate, The oxygen atmosphere pressure in the vacuum chamber was maintained at 30 Pa, and the target was irradiated with laser light having an energy density of 3 J / cm ² to laminate an amorphous second ion supply layer on the first ion supply layer.

(Formation of solid electrolyte layer)
Li _w A _x B _y O _z (where A is one selected from La and Si, or a predetermined distance from the outermost surface of the second ion supply layer provided on the first substrate) 2 and B is one or two selected from Ti and P, 0 <w ≦ 4, 0 ≦ x ≦ 1, 0 <y ≦ 1, 0 ≦ z ≦ 12) A solid electrolyte layer target composed of one or more selected from the above is disposed, the oxygen atmosphere pressure in the vacuum chamber is maintained at 10 Pa, and the target is irradiated with laser light having an energy density of 5.5 J / cm ^2. Then, an amorphous solid electrolyte layer was laminated on the second ion supply layer.

(Formation of coloring layer)
A coloring layer target made of WO ₃ is placed at a predetermined distance from the outermost surface of the solid electrolyte layer provided on the first substrate, and the oxygen atmosphere pressure in the vacuum chamber is maintained at 12 Pa. An amorphous coloring layer was laminated on the solid electrolyte layer by irradiating with a laser beam having a density of 5.5 J / cm ² .

(Formation of transparent electrode layer)
A transparent electrode layer target made of tin-doped indium oxide is disposed at a predetermined distance from the outermost surface of the color forming layer provided on the first substrate, and the oxygen atmosphere pressure in the vacuum chamber is maintained at 2 Pa. An amorphous transparent electrode layer was laminated on the color-developing layer by irradiation with a laser beam having an energy density of 7.1 J / cm ² .

  Next, a second base material was stuck on the transparent electrode layer to obtain an all solid-type electrochromic device of the example.

“Comparative Example 1”
An all-solid-type electrochromic device of Comparative Example 1 was obtained in the same manner as in the example except that the second ion supply layer was not provided on the first ion supply layer.

“Comparative Example 2”
A target for a first ion supply layer made of lithium iron phosphate having an olivine structure (LiFePO ₄ ) is disposed at a predetermined distance from the outermost surface of the electrode layer provided on the first substrate, and an oxygen atmosphere in a vacuum chamber The pressure is maintained at 30 Pa, the target is irradiated with laser light having an energy density of 3 J / cm ² , the first ion supply layer is laminated on the electrode layer, and then the first substrate provided on the first substrate A target for the first ion supply layer made of spinel lithium manganate (LiMn ₂ O ₄ ) is disposed at a predetermined distance from the outermost surface of the one ion supply layer, and the oxygen atmosphere pressure in the vacuum chamber is maintained at 30 Pa. , the target, by irradiating a laser beam energy density 3J / cm ^2, on the first ion supplying layer, except for laminating a second ion supply layer in the same manner as in example, all of Comparative example 2 To obtain a type electrochromic device.

[Evaluation of initial contrast]
The reflectivity (percentage) of the electrochromic device before voltage application with respect to visible light of 680 nm when the voltage of 3 V was applied for 4 seconds to the all solid-state electrochromic devices of Examples and Comparative Examples 1 and 2. By dividing by the reflectance (percentage) after voltage application, the initial contrast of each all-solid-state electrochromic device was measured.

As a result, the initial contrast of the all solid-state electrochromic device of the example was 6.6.
The initial contrast of the all solid-state electrochromic device of Comparative Example 1 was 2.6.
The all solid-state electrochromic device of Comparative Example 2 did not operate (color development).

[Evaluation of color repetitive performance]
With respect to the all-solid-state electrochromic elements of Examples and Comparative Examples 1 and 2, a voltage of 3 V was applied for 4 seconds until the contrast reached 2, and it was confirmed how many times the color development could be repeated.

As a result, the all solid-state electrochromic device of the example could repeat the color development 800 times.
The all solid-state electrochromic device of Comparative Example 1 was able to repeat color development 50 times.
The all solid-state electrochromic device of Comparative Example 2 did not operate (color development).

  From the above evaluation results, it was confirmed that the all-solid-state electrochromic device of the example was excellent in contrast and coloring repeatability.

DESCRIPTION OF SYMBOLS 10 ... All-solid-state electrochromic element, 11 ... 1st base material, 12 ... Electrode layer, 13 ... 1st ion supply layer, 14 ... 2nd ion supply layer, 15 ... Solid electrolyte layer, 16 ... coloring layer, 17 ... transparent electrode layer, 18 ... second substrate.

Claims (2)

A first base material, and an electrode layer, a first ion supply layer, a second ion supply layer, a solid electrolyte layer, a coloring layer, a transparent electrode layer, and a second group, which are sequentially laminated on one surface of the first base material An all-solid-state electrochromic device comprising a material,
The all-solid-state electrochromic device, wherein the first ion supply layer is made of spinel lithium manganate and the second ion supply layer is made of olivine lithium iron phosphate. The all-solid-state electrochromic device according to claim 1, wherein the first base material and / or the second base material is a paper base material.

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