JPH02207224A - Electrochromic element and production thereof - Google Patents

Abstract

PURPOSE:To provide sufficient insulation and isolation between electrodes and to reduce the thickness in an electrolyte part by forming a microporous film having many fine projections or many through-holes provided on an electrode surface in such a manner as to exist between the electrodes. CONSTITUTION:For example the electrode 7 coated with the microporous film consisting of a photoset layer formed with the many fine projections 6 preferably over the entire surface or the many very small through-holes over the entire surface on one or both surface of the electrode 7 is used. The many fine projections 6 or the microporous films are laminated so as to exist between the electrodes 7 and 8 and an electrolyte for an electrochromic element or solid high-polymer electrolyte 9 is interposed therebetween. The sufficient insulation and isolation between the electrodes 7 and 8 is obtd. in this way and the reduction of the electrolyte 9 part is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrochromic device that has a thin electrolyte portion and prevents short circuits when pressed from the outside.

[Prior Art and Problems] An electrochromic device (hereinafter abbreviated as an ECD device) is a display device that utilizes reversible color change due to applied voltage.

ECDs are characterized by being easy to view without display angle dependence, and have advantages such as memory performance, and are being actively researched and developed. Generally, the structure is an electrochemical cell consisting of a transparent conductive layer, an electrochromic layer (hereinafter abbreviated as EC layer), an electrolyte layer (EC layer), and a counter electrode. Since the characteristics of ECD largely depend on the movement process of ions, the response speed is slower than that of liquid crystal display elements, and improvements are desired.

In particular, the resistance of the electrolyte portion is a problem, and it is desired to make the electrolyte portion thinner in order to reduce the internal resistance.

Conventionally, liquid electrolytes and solid electrolytes have been known as electrolytes. As a liquid electrolyte, for example, Li as a supporting electrolyte is added to an organic solvent such as propylene carbonate i.
A solution of C-bun 04, LiCF3 SO3, etc. is used. Further, as solid electrolytes, solid polymer electrolytes and inorganic solid electrolytes in which the above-mentioned inorganic ions are mixed and dissolved in a polymer matrix having ion conductivity are known. Alternatively, a system in which the above liquid electrolyte is added to a solid polymer electrolyte is also known.

As mentioned above, the second method for improving ECD characteristics is to make the electrolyte part thinner, but in that case, when manufacturing the ECD element by laminating electrodes, there is a method of manufacturing the ECD element externally. has been reported (for example, Journal of the Photographic Society of Japan, Vol. 51, p. 375 (1986)).

However, the film thickness of the electrolyte portion is several tens of gm and the internal resistance is large, so it is desired to improve the characteristics of the ECD element such as response speed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ECD with a thin electrolyte portion that improves the problems of conventional ECD devices.
The purpose is to provide devices.

[Means for Solving the Problems] The present invention provides the following features: (1) The first electrode and the second electrode include (a) an electrochromic layer, (b) a large number of fine protrusions made of a photosensitive aromatic polymer, and/or Microporous membrane with many through holes,
(c) Electrochromic element, which is characterized by facing each other via an electrolytic solution and/or a solid electrolyte; (2) at least one electrode of an electrode or an electrode consisting of an electrode and an electrochromic layer; There is a problem in that when the substrate is pressed between the two electrodes, the first electrode and the opposing second electrode tend to short-circuit with each other.

In order to solve this problem, for example, JP-A-63-1
No. 39323 uses an electrolyte solution containing a photocurable resin, and as spacers for gap control, glass beads, glass fibers, ceramic particles, and plastic particles are placed on the first substrate before or at the same time as the electrolyte solution is supplied. A method for manufacturing an electrochromic device is described, which comprises: supplying a second substrate, then overlapping and pressing a second substrate, spreading an electrolyte solution within the substrate, and curing the electrolyte solution by irradiating ultraviolet rays. There is.

However, with this method, if the spacer is poorly dispersed, it may not necessarily be possible to obtain a uniform thickness, which may adversely affect the characteristics of the ECD element.

In addition, by using a poly(methacrylic oligooxyethylene)/lithium perchlorate composite system as a solid polymer electrolyte, a photosensitive aromatic polymer solution can be applied to opposing surfaces without using a spacer and then dried. A photosensitive film is formed, a negative or positive film with a fine film-like shape is adhered to the film, the surface is irradiated with light to harden the photosensitive film, and the uncured portion is removed with a developer. By exposing the surface of the electrode, the electrode has a microporous membrane with many fine protrusions and/or many through holes, and the surface with this membrane is used as the opposing surface of the two electrodes, and an electrochromic electrode is formed between the two electrodes. The above object has been achieved by providing the method for manufacturing an electrochromic device according to item 1 above, characterized in that an electrolytic solution and/or a solid electrolyte is interposed.

The formation of the photosensitive aromatic polymer in the present invention involves cross-linking the opposing surfaces of either the first electrode or the second electrode (the surface in contact with the electrolyte layer) with active light such as visible light, ultraviolet rays, and electron beams. A photosensitive aromatic polymer having a large number of "photosensitive groups" including ethylenically unsaturated groups to be polymerized (for example, photosensitive aromatic polyamide, photosensitive aromatic polyimide, etc.) is dissolved in an appropriate organic solvent. uniformly coated by a coating means at a coating temperature of preferably about 5 to 50°C, particularly 10 to 40°C, and drying the coated film by preferably gradually evaporating the solvent from the coated film (bribake); The thickness is preferably about 0.05-25 pLm, especially 0.3-1
A solidified film (photosensitive film) of the photosensitive aromatic polymer is formed.

The photosensitive aromatic polymer used in the present invention includes a large number of "photosensitive groups" having ethylenically unsaturated groups that can be photocrosslinked (photopolymerized) by active light such as visible light, ultraviolet rays, and electron beams. and retains highly photosensitive groups, such as N,N-dimethylformalumide.

N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-
Methyl-2-pyrrolidone, dimethyl sulfoxide.

High solubility that can be uniformly dissolved in organic polar solvents such as hexamethylene phosphoramide and diglyme, and active rays such as visible light, ultraviolet rays, and electron beams that pass through the difilm at approximately 100 to 300°C. The photosensitive film is sufficiently irradiated with a light beam so that a part of the photosensitive film (i.e., a part that will become a large number of minute protrusions) will not be easily dissolved in the developer used in the next step. is sufficiently photocured, and then, after removing the negative or positive film, "development" is carried out to expose the surface of the electrode in the uncured part of the photosensitive film, preferably at a temperature of about 0 to 80 °C. ``many fine protrusions'' or ``a microporous film having many minute through-holes'' made of a photocured layer formed by photocuring of a photosensitive film are preferably uniformly formed over the entire surface of the electrode. That's what I do.

As mentioned above, the negative or positive film j is
A large number of transparent parts (parts that allow light to pass through) correspond to parts such as "many minute protrusions" formed on the surface of the electrode, and other opaque parts (parts that do not allow light to pass through). Films with transparent parts and opaque parts with "fine patterns" can be made of photosensitive aromatic polyamides, which can be used at high temperatures, can be used at high temperatures, and are flame retardant against sparks. Photosensitive aromatic polymers such as polyaromatic polyimides are particularly preferred.

The solution of the photosensitive aromatic polymer is applied to the electrode using any means such as a roll coater, a doctor blade, a percoater, or a spin coater, so that the solution has a uniform thickness. It is sufficient to form a film.

In drying the coating film, the drying temperature is approximately 20 to 20°C.
It is preferable that the temperature is 0° C., especially about 30 to 150' C, and the drying time is about 0.1 to 100 minutes, particularly about 0.5 to 30 minutes.

In the present invention, after forming a photosensitive film on the surface of an electrode as described above, the portions that will become "many fine protrusions" etc. are then formed on the surface of the electrode by photo-curing of the photosensitive film. A "negative or positive film" on which "a large number of fine patterns" having a pattern corresponding to the planar shape of is formed is closely superimposed on the photosensitive film, and the negative or positive film may have a pattern, for example, Points: 9 circles, ellipses: 1 arc, crescent, star, L-shapes, crosses, quadrilaterals (squares, rhombuses, rectangles, etc.), triangles (isosceles triangles, equilateral triangles, etc.), hexagons, etc. planar shape (the maximum length is
Preferably about 0.5-2000gm, especially 1-500J
It is a precision machine in which a large number of "transparent parts" having a diameter of about Examples include negative or positive films having a pattern, and the area of the transparent portion is about 0.1 to 50%, particularly about 0.2 to 25%, of the total area of the negative or positive film. It is preferable that the ratio is .

Furthermore, the material of the negative or positive film is not particularly limited, and may be, for example, the same material as that commonly used for negative films such as photographs. An adhesive may be applied to one side of the negative or positive film so that it can be brought into close contact with the photosensitive film of the electrode.

In the present invention, by photocuring a photosensitive film using the above-mentioned Neka or positive film, a large number of extremely fine protrusions etc. are precisely and accurately arranged on the surface of the electrode. It can be easily formed with good reproducibility.

In the above-mentioned development, the developer may be one whose main component is the same solvent as the organic polar solvent used in the preparation of the photosensitive aromatic polymer solution, and the development operation is generally carried out according to the conventional method. A dipping method, a spray method, etc. can be used.

In the immersion method, ultrasonic waves may be applied.

The "many fine protrusions" or "microporous membrane having a large number of through holes" made of the photocured layer formed on the surface of the electrode retains the electrolyte in the gaps or through holes between the electrode and each projection. The height (thickness), size, shape, gap between each protrusion or each through-hole, alignment, etc. of the protrusion or microporous membrane may be adjusted as appropriate to enable the formation of a large number of microporous protrusions. When forming, the height of the protrusion is approximately 0.01 to 20p.
m. In the present invention, the above-mentioned large number of fine protrusions (protrusions made of a photocured layer) are preferably provided on one side or both sides of the "electrode" produced as described above. By using an electrode covered with a microporous film consisting of a photocured layer, which is formed uniformly over the entire surface or has many microscopic through holes formed over the entire surface, the large number of microscopic protrusions or The microporous membranes are stacked so that they are present between the electrodes, and an electrolytic solution or solid polymer electrolyte for the ECD element is interposed therebetween to produce an ECD element.

As the electrolytic solution or solid polymer electrolyte for the ECD element, an electrolytic solution in which a supporting electrolyte is dissolved in a non-aqueous organic solvent, or a solid polymer electrolyte in which the supporting electrolyte is dissolved in an ion-conducting polymer is used. As a supporting electrolyte,
Ions that cause the EC substance to develop and fade in color, such as protons and lithium ions.

Any substance that retains sodium ions etc. may be used.
For example, Li0Bun04, LiBF4.

LiAsF6, LiPF6, Li5CN, LiI.

In particular, it is preferably about 0.05 to 10 gm, and furthermore, the maximum length of each protrusion (maximum length in the same plane direction as the surface of the electrode) is about 0.05 to 10 gm. ．． 5-2000 pLm, especially 1-50
0 gm, and the cross-sectional area of each protrusion is approximately I x 1
0-7~1mm', especially lXl0-6-0.5mrri
It is preferable that it be about '.

The area of the portion where the above-mentioned "many fine projections" or "microporous film having many through-holes" are formed on the surface of the electrode is , based on the total area of the electrode, about 0.1 to 50%, especially 0
．． The proportion is preferably about 2 to 25%.

As mentioned above, "many fine protrusions" made of the photocured layer
The electrodes, which are uniformly formed over the entire surface, can be further heat treated (post-I bake) at a temperature of about 100 to 400°C, especially 150 to 250°C, for about 5 to 60 minutes. Increasing the adhesion between minute protrusions (photocured layer) and the electrode surface, or improving the physical properties of minute protrusions.

This is suitable for improving chemical resistance and the like.

Examples include LiBr, Na5CN, NaBF+, HCM04, etc. Two or more of these can be used in combination.

Examples of non-aqueous organic solvents include propylene carbonate, acetonitrile, and r-butyrolactone.

Ethylene carbonate, tetrahydrofuran.

Examples include organic solvents known as components of liquid electrolytes such as dimethoxyethane, dimethyl sulfoxide, dioxolane, and sulfolane, and liquid substances such as low molecular weight polyethylene glycol, polypropylene glycol, and copolymers thereof.

Ion-conducting polymers include polyethylene oxide,
Polymers such as polypropylene oxide, polyethylene sulfide, poly-β-propiolactone, and polyethylene succinate, or polymers obtained by polymerizing polyethylene glycol methacrylate and polyethylene glycol acrylate, and polyethylene oxide-added glycerin are crosslinked with diincyanate. Examples include polymers such as polysiloxane and polyphasphazene having polyethylene oxide in their side chains, and crosslinked polymers thereof.

Furthermore, in order to improve the mechanical properties of these polymers, thermoplastic elastomers such as polyurethane, high molecular weight polyethylene oxide, etc. may be mixed. In addition, for the purpose of increasing the ionic conductivity of the above-mentioned organic polymer, within the range of not impairing the mechanical strength of the solid polymer electrolyte,
The liquid electrolyte described above may also be included.

Alternatively, polyalkyl methacrylate may be added to a liquid electrolyte in which the lithium ion salt is dissolved in the above organic solvent.
), etc., or a liquid mixture consisting of a polymerizable monomer or macromer, a non-aqueous solvent, and a lithium ion salt, which is gelled by heat or irradiation with actinic rays. can also be used.

Specific examples of polymers and macromers that can be polymerized by actinic rays or heat include the following. Examples include acrylic acid ester, methacrylic esterate, triethylene glycol trimethylol propane triacrylate, and the above-mentioned ones in which the ethylene glycol structure is changed to a propylene glycol structure can also be used.

Alternatively, the ethylene glycol structure may be changed to a random or block copolymer structure of ethylene oxide and propylene oxide units.

Alternatively, reactive oligomers or polymers used in UV-curing paints can also be used. Examples include unsaturated acrylate prepolymers obtained by modifying unsaturated polyesters with acrylic acid, acrylic-modified siloxanes, and acrylic-modified polyurethane prepolymers. Two or more of these can be used in combination.

In addition to these, in order to improve the mechanical strength of the solid polymer electrolyte, a small amount of an elastomer such as polyurethane or a polymer such as high-molecular polyethylene oxide may be added.

Examples include methyl acrylate, ethyl acrylate,
Propyl acrylate, butyl acrylate.

Pentyl acrylate, aryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, aryl methacrylate, 2-hydroxyethyl acrylate.

Examples include 2-hydroxyethyl methacrylate, 1,6-hexanediol acrylate, and 1,6-hexanediol methacrylate.

Further, examples of acryloyl-modified polyalkylene oxide include diethylene glycol monoacrylate and diethylene glycol methacrylate.

Triethylene glycol monoacrylate, polyethylene glycol monoacrylate, methoxytetraethylene glycol monoacrylate.

Phenoxytetraethylene glycol monoacrylate, triethylene glycol monomethacrylate, polyethylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate, polyethylene glycol dimethacrylate. 0.01 to 50 wt%, preferably 0
．． The range of 1 to 30 wt% is preferable. If the lithium ion content is too high, the excess lithium ion salt will not dissociate and become a solid solution, but will simply be mixed together, resulting in a decrease in ionic conductivity. Furthermore, if the content is too low, the number of dissociated lithium ions, which are charge carriers, will decrease, resulting in a decrease in ionic conductivity.

As the electrode in the present invention, at least one substrate is made of a light-transmitting material and a transparent conductive layer is formed on the surface thereof. Furthermore, an EC layer is used on the surface of the transparent conductive layer of at least one electrode.

As the light-transmitting substrate, the transparent conductive layer, and the EC layer, conventionally known ones can be used as appropriate.

As the light-transmitting substrate, for example, a glass plate, an acrylic resin plate, etc. can be used.

As for the transparent conductive layer, for example, indium oxide-tin oxide (ITO), zinc oxide, titanium oxide.

Cadmium oxide or the like can be used.

The EC layer is, for example, tungsten oxide.

Molybdenum oxide, vanadium oxide, etc. can be used.

Next, one embodiment of the present invention will be described with reference to the drawings.

First, as shown in FIG. 1, a solution of a photosensitive aromatic polymer is applied to one side of the electrode 1 to form a coating film, and the coating film is dried (brined) to a thickness of about 0.05~ 25
gm photosensitive film (solidified film) 2 is formed. Then the second
As shown in the figure, a transparent portion 3, such as a small circle with a diameter of about 1 to 500 gm, is formed on the surface of the photosensitive film 2 of the electrode 1.
A negative film 4 having a large number of arranged at intervals of about 0.01 to 10 mm is brought into close contact with the negative film 4.
Light from a mercury lamp is applied to the photosensitive film 2 from above in the direction of arrow P.
irradiate and photocure. Next, the negative film 4
After removal, the insulation isolation between the developing devices is sufficient, and the characteristics of the ECD element are better than those of the prior art.

In addition, in conventional ECD elements, the electrolyte portion is approximately 20 pm
In the case of the fine protrusions of the present invention, the height is 0.01 to 20 pLm, especially 0.
．． It is easily possible to make it about 0.05-10 gm, and with such a large number of fine protrusions, sufficient E
Since it is possible to insulate and isolate the electrodes of the CD element, it is possible to significantly reduce the thickness of the ECD element that is finally manufactured.

[Examples and Comparative Examples] Example 1 An ITO glass electrode (surface resistance 7Ω/c) was used as an electrode substrate.
m') on the surface by electron beam evaporation method,
Tungsten oxide layer 2 as electrochromic layer
000 people were formed and the first electrode was created. A photosensitive aromatic polyimide varnish (PI-400 manufactured by Ube Industries Ltd., rotational viscosity: 130 centivoise) is applied to the surface of the first electrode using a spin coater device to form a coating film,
A developing operation is performed using the solution to remove the uncured portion of the surface of the electrode and expose the surface 5 of the electrode, and after immersing it in a rinsing solution of the developer, the entire electrode is dried in air at room temperature, and then Heat treatment is performed at 150-250°C for 10-30 minutes. As a result, a large number of fine protrusions (about 0.05 to 10 pm in height, 1 to 50 pm in diameter) as shown in Figs.
A circular cross section (about 0.0 m) 6 is formed in close contact with one side of the electrode 1. This obtained electrode will be referred to as the first electrode 7. next,
As shown in FIG. 5, the first electrode 7 shown in FIG. 3 and FIG. The electrode (counter electrode) 8 is superimposed on the first electrode 7 so that a large number of minute protrusions are present between the second electrode 8 and the electrolytic solution or solid polymer electrolyte 9 for the ECD element is applied thereto. An ECD element is manufactured by interposing the following steps.

The ECD element manufactured in the manner described above has "many fine protrusions" provided on the electrode surface between the electrodes that make up the ECD element, so the electrode coating film is immediately heated to 65°C.
Dry for 30 minutes (pre-baking process) to a thickness of 2.
, 3 pLm photosensitive film was formed on the electrode. On the surface of the photosensitive film of the electrode, a diameter of 30 gm and a diameter of 10 pm were applied.
A negative film having circular transparent parts at intervals of about 250 gm is closely attached to the mercury lamp, and a light beam from a mercury lamp (wavelength: 300 ~
The photosensitive film was irradiated with light (450 nm) for about 50 seconds to photocure portions corresponding to minute protrusions.

Next, using a special developer, the electrode having the irradiated photosensitive film is subjected to immersion development for 2 minutes to remove the uncured portion of the photosensitive film and form a large number of fine protrusions. Finally, the first layer was dried in air at room temperature, and then heat treated at 230°C for 30 minutes to form a photocured layer with many fine protrusions of 2 gm in height on one side. The electrode was manufactured.

The same ITO glass electrode as above was used as a counter electrode (second electrode) and laminated so that there were many fine protrusions between it and the above first electrode. The ECD element was manufactured by impregnating it with a dissolved electrolyte for an ECD element and electrically sealing the outside with an epoxy resin.

As a characteristic evaluation of the ECD element, a direct current voltage was applied, and the response change of color development and fading was measured using an ultraviolet-visible spectrophotometer. below,
The results are shown in Figure 6.

In addition, as a result of the suppression test, no short circuit between the first electrode and the second electrode was observed.

Comparative Example 1 In Example 1, a solid polymer electrolyte (50%
ECD by interposing a layer (m thickness) between the first electrode and the second electrode.
We created a device and measured the response change in color development and fading.

Comparative Example 2 In Example 1, a solid polymer electrolyte (2g
Although an ECD element was created by interposing a layer (m layer) between the first electrode and the second electrode, a short circuit between the electrodes was observed as a result of a pressure test.

[Effect of the invention] 8... second electrode, 9... Electrolyte, P...Direction of the light source (arrow).

Claims (2)

[Claims] (1) A microporous membrane in which the first electrode and the second electrode have (a) an electrochromic layer, (b) a large number of fine protrusions and/or a large number of through holes made of a photosensitive aromatic polymer,
(c) An electrochromic element, characterized in that the electrochromic elements are opposed to each other via an electrolytic solution and/or a solid electrolyte. (2) A solution of a photosensitive aromatic polymer is applied to the opposing surfaces of at least one electrode of an electrode or an electrode consisting of an electrode and an electrochromic layer, and then dried to form a photosensitive film. By closely adhering a negative or positive film with a fine film-like shape to the top, irradiating this surface with light to harden the photosensitive film, and removing the uncured part with a developer to expose the surface of the electrode, An electrode having a microporous membrane having many minute protrusions and/or many through holes, the surface with this membrane being the opposing surface of the two electrodes, and an electrochromic electrolyte and/or solid electrolyte interposed between the two electrodes. A method for manufacturing an electrochromic device according to claim 1, characterized in that: