KR101348004B1 - Electrochromic display apparatus - Google Patents

Abstract

An electrochromic display device of the present invention includes a display substrate; An opposite substrate disposed opposite the display substrate; An opposite electrode disposed on the opposite substrate; A plurality of display electrodes electrically isolated from each other and disposed between the display substrate and the counter electrode; A plurality of electrochromic layers disposed over corresponding display electrodes; And an electrolyte disposed between the display electrode and the counter electrode. The electrical resistance between one display electrode and the other display electrode is greater than the electrical resistance of one or the other display electrode. The at least one display electrode disposed between the display electrode closest to the display substrate and the counter electrode is configured to be permeable to the electrolyte.

Description

Electrochromic display device {ELECTROCHROMIC DISPLAY APPARATUS}

BACKGROUND OF THE INVENTION Field of the Invention The present invention generally relates to electrochromic display apparatuses and methods for manufacturing and driving electrochromic display apparatuses. In particular, the present invention relates to an electrochromic display device capable of independently displaying a multicolor, and a method of manufacturing and driving such an electrochromic display device.

Various electronic paper technologies have been developed to realize electronic paper that can replace paper as a display medium. Electronic paper generally refers to a display unit that mimics the characteristics of paper. For this reason, different characteristics are required for electronic paper than were required in conventional display devices such as cathode ray tubes (CRTs) and liquid crystal displays. Some of the requirements for electronic paper include the use of light reflective display principles (not light emitting); High white reflectivity; High contrast ratio; High display resolution; Memory (image retention) effects; Low voltage driving capability; Small size and light weight; And low cost. Among the above-mentioned properties, a particularly high level is required for properties related to display quality such as white reflectance and contrast ratio equivalent to paper.

Various modes of operation of electronic paper have been developed. Examples are reflective liquid crystal type, electrophoretic type and toner transfer type. However, using any of these known techniques, it is very difficult to provide multicolor displays while maintaining high back reflectance and high contrast ratio. Multicolor display can be realized using a color filter, but the color filter itself absorbs light and the reflectance is lowered. In addition, since the color culturator separates individual pixels into red (R), green (G), and blue (B), the reflectance of the display device is reduced, and as a result, the contrast ratio is also reduced. Reduction of the back reflectance and / or contrast ratio has a negative effect on visibility, making it difficult to use the display device as an actual electronic paper.

Other electronic paper technologies use the principle of electrochromism to realize reflective displays without using the color filters mentioned above. Electrochromism is a phenomenon in which a color of a compound can be reversibly changed based on a reversible redox reaction generated by applying a voltage. The electrochromic display device utilizes color development and discoloration for a compound ("electrochromic compound") exhibiting an electrochromism phenomenon. The electrochromic display device is reflective, has a memory effect, and can be operated at low voltage. For this reason, research and development of electrochromic technologies have been actively conducted in various aspects, including material development and device design, in order to provide a possible technology for realizing useful electronic paper.

However, the electrochromic display technology has a disadvantage in that the rate of color development and bleaching ("coloring / coloring response speed") is low due to the principle of coloration and bleaching based on the redox reaction. Japanese Laid-Open Patent Application 2001-510590 (Patent Document 1) discusses an improvement in color development / coloring response speed by fixing an electrochromic compound near an electrode. Patent document 1 improved the time required for color development / coloring from colorless to blue or colorless from blue to colorless, from about tens of seconds to about 1 second. However, these improvements are insufficient, and the development of useful electrochromic display devices requires further improvement of the color / bleaching response speed.

Still, it is expected that an electrochromic display technology having the ability to develop various colors depending on the structure of the electrochromic compound used will provide a useful multicolor display device. Several multicolor display devices using electrochromic display techniques are known. For example, Japanese Laid-Open Patent Application No. 2003-121883 (Patent Document 2) discloses a multicolor display device using an electrochromic layer of fine particles of a plurality of types of electrochromic compounds. Specifically, Patent Document 2 discusses a multicolor display device using a multilayer electrochromic compound containing a polymer compound having a plurality of functional groups having different voltages.

Japanese Laid-Open Patent Application No. 2006-106669 (Patent Document 3) discloses a display device capable of forming a multicolor by forming a plurality of electrochromic layers that color at different voltage or current values on an electrode. Specifically, Patent Document 3 discusses a multicolor display device having a display layer formed by stacking or mixing a plurality of electrochromic compounds having different threshold voltages or charge amounts required for color development.

Japanese Laid-Open Patent Application No. 2003-270671 (Patent Document 4) discloses a multicolor display device having a plurality of layers of structural units including a pair of transparent electrodes disposed between an electrochromic layer and an electrolyte. Japanese Laid-Open Patent Application 2004-151265 (Patent Document 5) discloses a multicolor display device corresponding to RGB three colors, wherein a passive matrix panel and an active matrix panel are formed using structural units according to Patent Document 4.

Such known multicolor display devices using electrochromic display technology have the following disadvantages. In the technique according to Patent Document 2, since the stacked electrochromic compounds color different colors at different voltages, one color can be colored by controlling the applied voltage, but not multicolors at the same time.

In the technique according to Patent Document 3, although a plurality of colors can be simultaneously developed due to the presence of a plurality of types of electrochromic compounds capable of developing different colors, complex voltage and current control is required to selectively color predetermined colors. Is needed.

The technique according to Patent Documents 4 and 5 requires a layer of a pair of transparent electrodes in order for one electrochromic layer to develop color. Thus, when a plurality of electrochromic layers are stacked, a plurality of electrode layers are required, so that reflectance or contrast is reduced.

Summary of the Invention

Disadvantages of the prior art include a display substrate in one aspect; An opposite substrate disposed opposite the display substrate; An opposite electrode disposed on the opposite substrate; A plurality of display electrodes isolated from each other and disposed between the display substrate and the opposite electrode; A plurality of electrochromic layers disposed over corresponding display electrodes; And an electrochromic display device including an electrolyte disposed between the display electrode and the counter electrode. The electrical resistance between one display electrode and the other display electrode is greater than the electrical resistance of one or the other display electrode. The at least one display electrode disposed between the display electrode disposed closest to the display substrate and the opposite electrode is configured to be permeable to the electrolyte.

The above and further advantages of the present invention will be better understood with reference to the following description in conjunction with the accompanying drawings, wherein
1 is a cross-sectional view of an electrochromic display device according to a first embodiment of the present invention;
2 is a perspective view of a display substrate of the electrochromic display device according to the first embodiment;
3 is a sectional view of an electrochromic display device according to a first modification of the first embodiment;
4 is a perspective view of an electrochromic display device according to a second modification of the first embodiment;
5 is a sectional view of an electrochromic display device according to a third modification of the first embodiment;
6A is a sectional view of an electrochromic display device according to a fourth modification of the first embodiment;
6B is a perspective view of an opposing substrate of the electrochromic display device of the fourth modification;
7 is a flowchart of a method of manufacturing an electrochromic display device according to the first embodiment;
8 is a sectional view of an image display device according to a second embodiment of the present invention;
9 is a perspective view of a display substrate of an image display device;
10 shows a driving circuit of an image display device;
11A is a plan view of the electrochromic display device according to the first embodiment;
FIG. 11B is a sectional view taken along line AA of FIG. 11A;
FIG. 11C is a cross-sectional view taken along the line BB of FIG. 11A;
12 is a graph showing measurement results of inter-electrode resistance between the first display electrode and the second display electrode of the electrochromic display device according to the first and second embodiments;
FIG. 13 is a graph showing a relationship between the number of pulse voltage application and the back reflectance of the first display electrode of the electrochromic display device of Example 4; FIG.
14 is a graph showing a relationship between the number of pulse voltage application and the back reflectance of the second display electrode of the electrochromic display device according to the fourth embodiment;
FIG. 15 is a graph showing a reflection spectrum during blue coloration from an electrochromic display device according to Example 4; FIG.
16 is a graph showing a reflection spectrum during green generation from the electrochromic display device according to the fourth embodiment;
17 is a graph showing a reflection spectrum during black color development from the electrochromic display device according to the fourth embodiment;
18A is a plan view of the electrochromic display device according to the fifth embodiment;
FIG. 18B is a sectional view taken along the line AA of FIG. 18A;
FIG. 18C is a sectional view taken along line BB of FIG. 18A; FIG.
19A to 19C show various methods of applying voltage to the electrochromic display device according to the fifth embodiment in order for the electrochromic display device to display various colors;
20 is a graph showing a reflection spectrum during magenta coloration from the electrochromic display device according to the sixth embodiment;
21 is a graph showing a reflection spectrum during yellow color development from the electrochromic display device according to the sixth embodiment.

Best Mode for Carrying Out the Invention

DETAILED DESCRIPTION Various embodiments of the invention are described below with reference to the drawings, wherein like reference numerals refer to the same or corresponding parts throughout the several views.

Embodiment 1

1 is a cross-sectional view of an electrochromic display device 10 according to an embodiment of the present invention. The electrochromic display device 10 includes a display substrate 11, an opposing substrate 12 disposed to face the display substrate 11, an opposing electrode 15 and a cell 15 disposed on the opposing substrate 12. Include. The cell 19 is formed by connecting the display substrate 11 and the opposing substrate 12 through the spacers 18. 2 is a perspective view of the electrochromic display apparatus 10. First, the structure of the electrochromic display device 10 according to the present embodiment will be described.

As shown in FIGS. 1 and 2, the electrochromic display apparatus 10 may include a first display electrode 13a formed on the display substrate 11; A first electrochromic layer 14a disposed on the first display electrode 13a; An insulating layer 22 disposed on the first electrochromic layer 14a; A second display electrode 13b disposed on the insulating layer 22; And a second electrochromic layer 14b disposed on the second display electrode 13b. Thus, the display substrate 11 supports a stack of various layers.

The first display electrode 13a is configured to control the potential between the first electrochromic layer 14a and the counter electrode 15 to color the first electrochromic layer 14a. The first electrochromic layer 14a includes a first electrochromic compound 16a and a metal oxide 17 supporting the first electrochromic compound 16a. The first electrochromic compound 16a develops color based on the redox reaction. The metal oxide 17 is configured to support the first electrochromic compound 16a as well as to speed up the color development / discoloration.

1 shows a single molecule in which the electrochromic compound 16a is adsorbed onto the metal oxide 17, but this is only an example of an ideal state. In practice, the first electrochromic compound 16a is fixed as long as the electrochromic compound 16a is fixed and there is an electrical connection so that the exchange of electrons due to oxidation and reduction of the electrochromic compound 16a is not hindered. The structure of is not specifically limited. Preferably, the electrochromic compound 16a and the metal oxide 17 may be mixed in a single layer.

The insulating layer 22 is provided to electrically isolate the first display electrode 13a from the second display electrode 13b. Preferably, the insulating layer 22 may not be provided if sufficient resistance can be secured between the first display electrode 13a and the second display electrode 13b. The film thickness of the first electrochromic layer 14a may be increased to increase the resistance between the first display electrode 13a and the second display electrode 13b.

The second display electrode 13b is configured to color the second electrochromic layer 14b by controlling the potential between the second electrochromic layer 14b and the counter electrode 15 so as to color the second electrochromic layer 14b. Similar to). The second electrochromic layer 14b includes a second electrochromic compound 16b and a metal oxide 17 supporting the second electrochromic compound 16b. The second electrochromic compound 16b is configured to develop color corresponding to the redox reaction. The metal oxide 17 not only increases the color development / bleaching speed but also serves to support the second electrochromic compound 16b. The second electrochromic compound 16b and the first electrochromic compound 16a are configured to develop different colors.

The resistance ("inter-electrode resistance") between the first display electrode 13a and the second display electrode 13b needs to be high enough to independently control their potential with the counter electrode 15. Specifically, the interelectrode resistance needs to be at least larger than the sheet resistance of the first display electrode 13a or the second display electrode 13b. When the inter-electrode resistance is less than the sheet resistance of the first display electrode 13a or the second display electrode 13b, when the voltage is applied to the first display electrode 13a or the second display electrode 13b, approximately the same voltage This can be applied to other display electrodes. As a result, the corresponding electrochromic layers 14a and 14b of the first display electrode 13a and the second display electrode 13b cannot be independently colored or discolored. Preferably, the interelectrode resistance is at least 500 times the sheet resistance of each display electrode.

To obtain proper insulation, the interelectrode resistance can be controlled by changing the thickness of the first electrochromic layer 14a. Alternatively, the inter-electrode resistance may be controlled by changing the thickness of the insulating layer 22 disposed on the first electrochromic layer 14a.

The interelectrode resistance of the first display electrode 13a and the second display electrode 13b may correspond to an electrical resistance between one of the plurality of display electrodes and another of the plurality of display electrodes.

The counter electrode 15 disposed on the counter substrate 12 controls the potential between the first and second display electrodes 13a and 13b and the counter electrode 15 to control the first and second electrochromic layers 14a and 14b. Is developed). The cell 19 is filled with electrolyte 20. The electrolyte 20 causes the ions (charges) to move between the first or second display electrode 13a or 13b and the counter electrode 15 so as to color the first or second electrochromic layer 14a or 14b. It is composed. The electrolyte 20 may be supported by a polymer. In this case, the polymer can be patterned to easily form the chromogenic / discolored regions (ie pixels).

Cell 19 may also include a white reflective layer 21. The white reflective layer 21 may be provided to improve the reflectance of the electrochromic display device 10. The white reflective layer 21 may be formed by injecting an electrolyte 20 in which white dye particles are dispersed in the cell 19. Alternatively, the white reflective layer 21 may be formed by coating the counter electrode 15 with a resin in which white dye particles are dispersed.

The white reflecting layer 21 is arranged in close proximity to the opposing substrate 12 such as the electrochromic layer 14b of FIG. 1 (first and second display electrodes 13a and 13b, first and second electro). One of the chromic layers 14a and 14b and the insulating layer 22, and the counter electrode 15. Preferably, the white reflective layer 21 may be disposed on the side of the counter substrate 12 opposite to the side on which the counter electrode 15 is formed.

Also preferably, a protective layer of an organic polymer material may be formed on the surface of the first or second electrochromic layer 14a or 14b on the side facing the display substrate 11. In this way, improved adhesion between the first or second electrochromic layers 14a or 14b and their respective proximal layers, and also the resistance of the first or second electrochromic layers 14a or 14b to solvents The durability of the electrochromic display device 10 may be improved by improving.

Preferably, an inorganic protective layer may be formed between the second electrochromic layer 14b and the electrolyte 20. In this way, improved solvent resistance and corrosion resistance of the second electrochromic layer 14b with respect to the electrolyte 20 can be obtained, thereby improving durability of the electrochromic display device 10.

The multicolor display operation of the electrochromic display device 10 will be described below. By the structure of the electrochromic display device 10 described above, multicolor display can be easily performed. That is, since the first and second display electrodes 13a and 13b are separated by the insulating layer 22, the potentials of the first and second display electrodes 13a and 13b with respect to the counter electrode 15 are independent. Can be controlled by This makes it possible to independently colorize or discolor the first electrochromic layer 14a disposed on the first display electrode 13a and the second electrochromic layer 14a disposed on the second display electrode 13b.

Since the first and second electrochromic layers 14a and 14b are stacked on the display substrate 11, a multicolor display can be provided according to the color development / discoloration pattern of the first and second electrochromic layers 14a and 14b. have. That is, the following three different color / bleaching patterns can be produced: 1) color only from the first electrochromic layer 14a; 2) color development only from the second electrochromic layer 14b; And 3) color development from both the first and second electrochromic layers 14a and 14b. For example, the first and second electrochromic layers 14a and 14b are configured to develop two different colors selected from red, green and blue to achieve multicolor display.

In this embodiment, the white reflective layer 21 disposed in the cell 19 provides improved back reflectance. As a result, it is possible to compensate for the decrease in reflectance due to the layered structures of the first and second electrochromic layers 14a and 14b, thereby enabling multicolor display with improved visibility.

In addition, according to this embodiment, the first and second electrochromic compounds 16a and 16b are supported by the respective metal oxides 17. This structure enables multicolor display with increased color / color response. This structure is particularly effective when an organic compound material having a low electron (or hole) mobility is used for the first or second electrochromic compound 16a or 16b. This means that according to this embodiment, the electrons (or holes) are electrons (or holes) rather than the first or second electrochromic compounds 16a or 16b rather than the first or second electrochromic compounds 16a or 16b. This is because the metal oxide 17 having high mobility can move from the first or second display electrode 13a or 13b. Therefore, color development / discoloration can occur at a high speed, which enables multicolor display with increased coloration / discoloration response speed.

According to this embodiment, while the electrolyte 20 penetrates the electrochromic display element of the electrochromic display device 10 for the color development / coloring reaction, electric charges are injected into the respective electrochromic layers 14a and 14b. . This means that the applied voltage and the response speed may be influenced by the penetration of the electrolyte 20, so that the color reaction may not occur depending on the electrolyte penetration. Therefore, the electrolyte must be properly infiltrated into both the first and second display electrodes 13a and 13b, the insulating layer 22, the first and second electrochromic layers 14a and 14b, and the white reflective layer 21.

This can be accomplished by various methods. For example, one method may involve stacking electrolytes while penetrating the display electrodes 13a and 13b, insulating layers 22, and electrochromic layers 14a and 14b during device fabrication. Another method may involve applying an electrolyte containing polymer between the layers. In another method, a polymer film containing an electrolyte or the like can be used as the insulating layer 22. In another method, an electrolyte containing resin can be used as a binder for the white particles in the white reflective layer. Thus, the white reflective layer may comprise a dispersion of white particles in the electrolyte containing resin.

Alternatively, one display electrode disposed between the other display electrode closest to the display substrate 11 and the counter electrode 15, that is, the second display electrode 13b of the present embodiment, has a permeability to the electrolyte 20. It can be configured to. The insulating layer 22 can also be configured to be permeable to the electrolyte 20. The electrolyte layer may be disposed between any two layers of the first and second display electrodes 13a and 13b, the first and second electrochromic layers 14a and 14b, and the insulating layer 22.

Thus, according to this embodiment, a plurality of display electrodes and an electrochromic layer are laminated, wherein the individual display electrodes and the electrochromic layer are insulated from each other. Therefore, only the corresponding electrochromic layer of each display electrode, that is, the electrochromic layer positioned between the counter electrode and the specific display electrode, can be colored or quenched. This is a method of controlling the first and second electrochromic layers separately to color or discolor. However, when a high voltage is applied to one display electrode (e.g., the second display electrode 13b), the charge is displayed as well as the corresponding electrochromic layer (e.g., the second electrochromic layer 14b) facing the counter electrode 15. It may diffuse toward the opposite side of the electrode (eg, the first electrochromic layer 14a). As a result, color development / discoloration can be induced in the first electrochromic layer (for example, the first electrochromic layer 14a) on the opposite side facing the display substrate 11 of the display electrode.

To prevent the above phenomenon, one of the electrochromic layers closest to the display substrate 11, for example, the first electrochromic layer 14a, which has the highest threshold voltage for color development or discoloration, may be provided. In this way, since no electrochromic layer exists on the opposing layer of the display electrode (for example, the first display electrode 13a) that does not face the opposing electrode 15, application of a high voltage to the second display electrode 13b is prevented. It does not induce the undesirable color development / coloring reactions described above.

Next, the material used for the electrochromic display device 10 according to the first embodiment will be described. First, the materials of the display substrate 11 and the various layers formed on the display substrate 11 will be described. The material of the display substrate 11 is not particularly limited as long as it is transparent. Examples are glass and plastic films.

The materials of the first and second display electrodes 13a and 13b are not particularly limited as long as they are electrically conductive and optically transparent. These characteristics are necessary to improve the visibility of the color developed by the electrochromic layers 14a and 14b. Examples of such transparent conductive materials include inorganic materials such as indium oxide ("ITO") doped with tin; Tin oxide doped with fluorine ("FTO"); And tin oxide ("ATO") doped with antimony. A preferred example is an electrochromic film of an organic material comprising at least one of indium oxide, tin oxide and zinc oxide, formed by a vacuum film forming method. Such indium oxide, tin oxide and zinc oxide materials can be easily formed into a film by sputtering, which can also provide adequate transparency and electrical conductivity. Among these, InSnO, GaZnO, SnO, In ₂ O ₃ , ZnO are particularly preferable.

The material of the first and second electrochromic compounds 16a and 16b of the first and second electrochromic layers 14a and 14b may include a material exhibiting color change based on the redox reaction. Examples of such materials include known electrochromic compounds of the polymer type, dye type, metal complex type and metal oxide type.

Examples of polymeric and dye-type electrochromic compounds are low molecular weight organic electrochromic compounds such as azobenzene, anthraquinone, diarylethene, dihydropyrene, styrene, styryl, spiropyran, spiroxazine, spirothio Pyran, thioindigo, tetrathiafulvalene, terephthalic acid, triphenylmethane, triphenylamine, naphthopyran, viologen, pyrazoline, phenazine, phenylenediamine, phenoxazine, phenothiazine, phthalocyanine, fluorane, Fulgide, benzopyran and metallocene compounds. Examples also include electrically conductive high molecular compounds such as polyaniline and polythiophene.

Among those mentioned above, a viologen compound represented by the following general formula (1) or a terephthalic acid compound represented by the following general formula (2) is particularly preferable.

상기 화학식에서, R1, R2 및 R3은 독립적으로 치환기를 포함할 수 있는 탄소수 1, 2, 3 또는 4의 알킬기 또는 아릴기이고, R1 및 R2 중 하나는 COOH, PO(OH)₂ 및 Si(OC_kH_2k+1)₃에서 선택되며; X는 1가 음이온이고; n은 0, 1 또는 2이며; m은 0, 1, 2, 3 또는 4이고; k는 0, 1 또는 2이다.

In the above formula, R 1, R 2 and R 3 are independently an alkyl or aryl group having 1, 2, 3 or 4 carbon atoms which may include substituents, and one of R 1 and R ₂ is COOH, PO (OH) ₂ and Si (OC). _k H _{2k + 1} ) ₃ ; X is a monovalent anion; n is 0, 1 or 2; m is 0, 1, 2, 3 or 4; k is 0, 1 or 2;

상기 화학식에서, R4, R5 및 R6은 탄소수 1, 2, 3 또는 4의 알킬기, 알콕시기 또는 아릴기이고, R4 및 R5 중 하나는 COOH, PO(OH)₂ 및 Si(OC_kH_2k+1)₃에서 선택되며; q는 1 또는 2이며; p는 0, 1, 2, 3 또는 4이고; k는 0, 1 또는 2이다.

In the above formula, R 4, R 5 and R 6 are alkyl, alkoxy or aryl groups having 1, 2, 3 or 4 carbon atoms, and one of R 4 and R 5 is COOH, PO (OH) ₂ and Si (OC _k H _{2k + 1} ) Is selected from ₃ ; q is 1 or 2; p is 0, 1, 2, 3 or 4; k is 0, 1 or 2;

Since such a material has a low coloration / coloring potential, it is possible to provide an appropriate color value in an electrochromic display device having a plurality of display electrodes.

Preferably, the first and second electrochromic compounds 16a and 16b may include a compound represented by the following formula (3), wherein the heterocyclic compound derivative structure is located between two pyridine ring alkyl cation structures. . These materials have high memory characteristics, which increase image retention time and reduce power consumption.

상기 화학식에서, R1, R2 및 R3은 독립적으로 치환기를 포함할 수 있는 탄소수 1, 2, 3 또는 4의 알킬기 또는 아릴기이고, R1 및 R2 중 하나는 COOH, PO(OH)₂ 및 Si(OC_kH_2k+1)₃에서 선택되며; X는 1가 음이온이고; n은 0, 1 또는 2이며; m은 0, 1 또는 2이고; k는 0, 1 또는 2이며; A는 복소환 화합물 유도체이다.

In the above formula, R 1, R 2 and R 3 are independently an alkyl or aryl group having 1, 2, 3 or 4 carbon atoms which may include substituents, and one of R 1 and R ₂ is COOH, PO (OH) ₂ and Si (OC). _k H _{2k + 1} ) ₃ ; X is a monovalent anion; n is 0, 1 or 2; m is 0, 1 or 2; k is 0, 1 or 2; A is a heterocyclic compound derivative.

Preferably, the first and second electrochromic compounds 16a and 16b may comprise a viologen compound. Preferably, they may comprise terephthalic acid compounds. Preferably, they may comprise a compound in which the heterocyclic compound derivative structure is located between two pyridine ring alkyl cation structures. By using a material having a similar molecular structure, the first and second display electrodes 13a and 13b having substantially similar color development / coloring potentials can be provided, thereby facilitating their coloration / coloration using the same electrolyte. Control is possible.

 Examples of the electrochromic compounds of the metal complex type and the metal oxide type include inorganic electrochromic compounds such as titanium oxide, vanadium oxide, tungsten oxide, indium oxide, iridium oxide, nickel oxide and prussian blue. The material of the metal oxide 17 is not specifically limited. Examples include metal oxides comprising any of the following as main components: titanium oxide, zinc oxide, tin oxide, aluminum oxide ("alumina"), zirconium oxide, cerium oxide, silicon oxide ("silica"), yttrium oxide Boron oxide, magnesium oxide, strontium oxide, potassium titanate, barium titanate, calcium titanate, calcium oxide, ferrite, hafnium oxide, tungsten oxide, iron oxide, copper oxide, nickel oxide, cobalt oxide, barium oxide, strontium oxide, vanadium oxide, Aluminum silicate, calcium phosphate and alumina silicate. These metal oxides can be used individually or in mixtures with two or more of the aforementioned components.

In terms of electrical and physical properties such as electrical conductivity and optical properties, color development using compounds selected from titanium oxide, zinc oxide, tin oxide, alumina, zirconium oxide, iron oxide, magnesium oxide, indium oxide and tungsten oxide or mixtures thereof Multicolor display with high color response speed can be achieved. In particular, by using titanium oxide, a multicolor display with a high color development / coloring response speed can be achieved.

The shape of the metal oxide 17 is not particularly limited. Preferably, the shape of the metal oxide 17 has a large surface area (“specific surface area”) per unit volume so that the metal oxide 17 can efficiently support the first and second electrochromic compounds 16a and 16b. It is a shape to make it. For example, by forming the metal oxide 17 from an aggregate of nanoparticles, a large specific surface area can be achieved, and the metal oxide 17 can efficiently support the electrochromic compound, thereby improving the color / color display contrast ratio. Multicolored display becomes possible.

Also preferably, plural kinds of particles having different particle diameters may be mixed. The presence of particles with different particle diameters can provide voids in the electrochromic layer, resulting in improved electrolyte permeability. Layers comprising mixtures of such particles having different particle diameters can also have improved strength against deformation of the layer that occurs upon coating, such as to improve yield during device fabrication.

Electrochromic compounds 16a and 16b may be supported on metal oxide 17 through a mixture of layers of electrochromic compounds 16a or 16b and metal oxides 17. However, in order to improve the coloration / discoloration display contrast ratio in the multicolor display, it is preferable to use a structure in which the electrochromic compound 16a or 16b is adsorbed to the metal oxide 17 through the adsorbent group.

The material of the insulating layer 22 is not particularly limited as long as it is porous and has appropriate insulating properties. Preferably, the material is durable and excellent in film formation characteristics. Preferably, the material may comprise ZnS. ZnS provides the advantage that it can be formed into a film on the electrochromic layer 14a quickly by sputtering without damaging the electrochromic layer 14a. Examples of materials containing ZnS as main components include ZnO-SiO ₂ , ZnS-SiC, ZnS-Si, and ZnS-Ge, where the content of ZnS is such that appropriate crystal properties will be maintained when forming the insulating layer 22. So that it may preferably range from about 50 to about 90 mole percent. Thus, particularly preferred examples are ZnS-SiO ₂ (8/2), ZnS-SiO ₂ (7/3), ZnS and ZnS-ZnO-In ₂ O ₃ -Ga ₂ O ₃ (60/23/10/7) to be.

By using the above-mentioned materials for the insulating layer 22, an appropriate insulating effect can be obtained from the thin film, thereby reducing the strength of the insulating layer 22 due to the multilayer stacking which can cause peeling of the insulating layer 22. Can be prevented. By forming the insulating layer 22 as a particle film, the porous film of the insulating layer 22 can be obtained. For example, when sputtering ZnS, a porous film of ZnS can be formed by forming a particle film as an undercoat layer in advance. In this case, the metal oxide 17 may be formed as such a particle film, but a porous particle film including, for example, silica or alumina, may be formed as part of the insulating layer 22. By forming the insulating layer 22 as a porous film, permeation of the electrolyte 20 through the insulating layer 22 becomes possible, thereby enabling movement of ions (charges) in the electrolyte 20 reacting to the redox reaction. Therefore, multicolor display with improved color / coloring response speed becomes possible.

The film thickness of insulating layer 22 may preferably range from 20 to 500 nm, more preferably from 50 to 150 nm. If the film thickness is less than the above range, the predetermined insulation cannot be obtained. If the film thickness exceeds the above range, manufacturing cost may increase, and visibility may decrease due to coloring.

Next, the material of the counter substrate 12 and the counter electrode 15 formed on the counter substrate 12 will be described. The material of the opposing substrate 12 is not particularly limited. The material of the counter electrode 15 is not particularly limited as long as it is electrically conductive. When the opposing substrate 12 comprises a glass substrate or a plastic film, examples of the material of the opposing electrode 15 include a transparent conductive film of ITO, FTO or zinc oxide; Conductive metal films of zinc or platinum; And carbon. Such a transparent conductive film or conductive film of the counter electrode 15 may be coated on the counter substrate 12. When a metal plate such as zinc is used as the counter substrate 12, the counter substrate 12 can also serve as the counter electrode 15.

When the material of the counter electrode 15 is configured to exhibit an inverse reaction with the redox reaction exhibited by the first electrochromic layer 14a or the second electrochromic layer 14b, stable color development / discoloration can be achieved. have. Specifically, when the first and second electrochromic layers 14a and 14b color by oxidation, the material of the counter electrode 15 may be configured to exhibit a reduction reaction. When the first and second electrochromic layers 14a and 14b are configured to color by reduction, the material of the counter electrode 15 may be configured to exhibit an oxidation reaction. In this way, the color development / discoloration reaction of the first and second electrochromic layers 14a and 14b can be made more stable.

Next, the materials of the electrolyte 20 and the white reflective layer 21 will be described. In general, the material of the electrolyte 20 includes a supporting salt dissolved in a solvent. Examples of supported salts include inorganic ionic salts such as alkali metal salts and alkaline earth metal salts; Quaternary ammonium salts; mountain; And alkalis. Specific examples include LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ COO, KCl, NaClO ₃ , NaCl, NaBF ₄ , NaSCN, KBF ₄ , Mg (ClO ₄ ) ₂ and Mg (BF ₄ ) ₂ . Examples of the solvent include propylene carbonate, acetonitrile, γ-butyrolactone, ethylene carbonate, sulfolane, dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,2-dimethoxyethane, 1, 2-ethoxymethoxyethane, propylene glycol and alcohols. The material of the electrolyte 20 is not limited to a liquid electrolyte containing a supporting salt dissolved in a solvent. Preferably, electrolyte 20 may comprise a solid electrolyte, such as a gel electrolyte or a polymer electrolyte.

Examples of the material of the white pigment particles included in the white reflective layer 21 include titanium oxide, aluminum oxide, zinc oxide, silica, cesium oxide and yttrium oxide. By mixing particles having light-storing properties with the pigment particles, the luminance of the reflective layer 21 can be improved by external light energy, and brighter display can be performed. Thus, the white reflective layer 21 may preferably comprise a material having photoluminescence. The white reflective layer 21 can improve reflection contrast and visibility. As described below with reference to the fourth modification of the first embodiment, the function of the white reflective layer can be provided by mixing the white pigment particles with the polymer electrolyte.

Therefore, according to this embodiment, the potentials of the first and second display electrodes in the electrochromic display device 10 are independently controlled so that the first and second electrochromic layers 14a and 14b independently color / develop. It may be possible to perform bleaching. Therefore, an electrochromic display device capable of generating a predetermined color by a simple control process can be provided.

The organic polymer material of the above-mentioned protective layer formed on the first and / or second electrochromic layers 14a and 14b may be selected from conventional resins in view of the adhesion of the electrochromic layer 14. Examples of such resins include polyvinyl alcohol, poly-N-vinyl amides, polyesters, polystyrenes and polypropylenes.

Modification 1

With reference to FIG. 3, the 1st modification of the specific example 1 is demonstrated. 3 is a schematic cross-sectional view of the electrochromic display device 10 according to Modification Example 1. FIG. The electrochromic display device 10a differs from the electrochromic display device 10 according to Embodiment 1 in that the electrochromic display device 10a includes three display electrode layers and three electrochromic layers.

As shown in FIG. 3, the electrochromic display apparatus 10 includes a display substrate 11a; A first display electrode 13a formed on the display substrate 11a; A first electrochromic layer 14a disposed on the first display electrode 13a; A first insulating layer 22a disposed on the first electrochromic layer 14a; A second display electrode 13b disposed on the first insulating layer 22a; A second electrochromic layer 14b disposed on the second display electrode 13b; A second insulating layer 22b disposed on the second electrochromic layer 14b; A third display electrode 13c disposed on the second insulating layer 22b; And a third electrochromic layer 14c disposed on the third display electrode 13c.

Such a structure of the electrochromic display device 10a facilitates multicolor display. Since the first, second and third display electrodes 13a, 13b and 13c are isolated from each other by the first and second insulating layers 22a and 22b, the first, second and third display electrodes ( The potential between 13a, 13b and 13c and counter electrode 15 can be controlled independently. As a result, the first, second, and third electrochromic layers 14a, 14b, and 14c disposed on the first, second, and third display electrodes 13a, 13b, and 13c respectively independently colorize / discolor. You can do it. Since the first, second, and third electrochromic layers 14a, 14b, and 14c are laminated on the display substrate 11a, various color development / discoloration patterns can be realized to provide multicolor display.

For example, 1) it is possible to color the first, second or third electrochromic layer 14a, 14b or 14c; 2) can develop first and second electrochromic layers 14a and 14b; 3) first and third electrochromic layers 14a and 14c can be colored; 4) can develop second and third electrochromic layers 14b and 14c; 5) The first, second and third electrochromic layers 14a, 14b and 14c can all be colored.

Preferably, the first, second and third electrochromic layers 14a, 14b and 14c may be configured to color yellow, magenta and cyan, respectively. In this way, the electrochromic display device 10 may perform full color display by independently controlling the potentials of the first, second, and third display electrodes 13a, 13b, and 13c.

Therefore, according to this modification of the specific example 1, the electrochromic display device 10a can develop various colors by a simple control operation.

Modification 2

With reference to FIG. 4, the 2nd modified example of the specific example 1 is demonstrated. 4 is a schematic perspective view of a display substrate 11b of the electrochromic display device according to Modification Example 2. FIG. The electrochromic display device of Modification 2 is different from the electrochromic display device 10 of Modification 1 in that the second display electrode 13b has a mesh lattice structure in plan view. The structure is contrasted with the specific example 1 in which the second display electrode 13b is formed on the entire surface of the display substrate 11.

The mesh lattice structure of the second display electrode 13b may promote the movement of ions (charges) in the electrolyte 20 in response to the redox reaction, thereby improving the color development / coloring response speed of the multicolor display. Therefore, according to the modification 2 of the specific example 1, the electrochromic display apparatus can perform multicolor display at high speed based on a simple control operation.

Modification 3

Next, the third modification of the specific example 1 is demonstrated with reference to FIG. 5 is a schematic cross-sectional view of an electrochromic display device 10c according to a third modification. The electrochromic display device 10c differs from the electrochromic display device 10 of Embodiment 1 in that the insulating film 22 is not provided.

Referring to FIG. 5, according to the third modified example, in the electrochromic display device 10c, the first electrochromic layer 14a disposed on the first display electrode 13a does not have an insulating layer therebetween. And is substantially isolated from the display electrode 13b. By controlling the resistance of the first electrochromic layer 14a, the inter-electrode resistance between the first display electrode 13a and the second display electrode 13b can be set higher than the sheet resistance of both display electrodes.

Therefore, the potentials of the first and second display electrodes 13a and 13b can be controlled independently without providing the insulating layer 22. Since the first and second electrochromic layers 14a and 14b can be independently colored / decolored, the electrochromic display device 10c can develop various colors by a simple control operation.

Modification 4

6A and 6B, an electrochromic display device 10d according to a fourth modified example of the specific example 1 will be described. 6A is a schematic cross-sectional view of the electrochromic display device 10d. 6B is a schematic perspective view of the opposing substrate 12a of the electrochromic display device 10d.

The electrochromic display device 10d differs from the electrochromic display device 10 of the specific example 1 in that the electrolyte 20a is patterned in a matrix form. Preferably, the white reflective layer 21 can be similarly patterned. In this case, the white reflective layer 21 may be stacked on the patterned electrolyte 20a. Alternatively, as shown in FIG. 6A, the white reflective layer 21 may be mixed with the electrolyte 20a.

The electrolyte 20a can be patterned by various methods. In one example, the electrolyte 20a may be mixed with a solvent, a transparent ink, or a white ink, and then the electrolyte 20a may be patterned by applying a mixture according to a predetermined pattern using an inkjet method or a screen printing method. Such inks may include conventional UV curable inks or thermal curable inks. In order to hold the electrolyte 20a or the solvent, a material having a low density structure having a low crosslinking ratio can be used.

The electrolyte 20a may comprise a polymer electrolyte. In this case, the insulating layer 22 may include an electrolyte 20a including a polymer electrolyte. In general, the patterning of the plurality of display electrodes and the electrochromic layer in a matrix form excessively increases the manufacturing cost. This increase in manufacturing cost can be prevented by a simple application method of the electrolyte 20a according to the present embodiment, and the polymer electrolyte is applied in a predetermined matrix pattern.

When the electrolyte 20a is patterned into a matrix as shown in FIGS. 6A and 6B, the counter electrode 15a may also be patterned to independently control the voltage between the electrolyte 20a and each display electrode. .

Preferably, the electrolyte 20a can be patterned in correspondence with the pixel electrode, and as described later with reference to the specific example 2, the plurality of display electrodes or the plurality of electrochromic layers are individually patterned by the active matrix without patterning. The pixels can be driven independently.

Manufacturing Method of Electrochromic Display Device According to Specific Example 1

The manufacturing method of the electrochromic display device 10 according to the specific example 1 will be described with reference to the flowchart of FIG. 7.

Formation of the first display electrode

In step S11, the first display electrode 13a is formed on the display substrate 11 by, for example, a vacuum deposition technique such as vapor deposition, sputtering or ion plating.

Formation of the First Electrochromic Layer

In step S12, the first electrochromic layer 14a including the first electrochromic compound 16a and the metal oxide particles 17 is formed on the first display electrode 13a by, for example, spin coating or screen printing. . Specifically, a liquid coating ink may be prepared by dispersing or dissolving the metal oxide particles 17 and the electrochromic compound 16a in a solvent, and then coating the coating ink on the first display electrode 13a by spin coating. Can be applied to form the first electrochromic layer 14a. Alternatively, the coating ink may be applied to the display substrate 11 by screen printing to form the first electrochromic layer 14a.

Inks for adjusting the coating ink may include a variety of known solvents such as water, alcohols, cellosolves, halogenated carbons, ketones and ethers. A coating ink mixture of the electrochromic compound 16a and the metal oxide particles 17 may be applied to coat the first electrochromic layer 14a at a time. Alternatively, after applying the dispersion of the metal oxide particles 17, the electrochromic compound 16a may be applied to the layer of the metal oxide particles 17 to coat the first electrochromic layer 14a.

Formation of the first insulating layer

In step S13 of FIG. 7, the first insulating layer 22 is formed on the first electrochromic layer 14a by a vacuum deposition method such as vapor deposition, sputtering and ion plating.

Formation of Second Display Electrode and Electrochromic Layer

In steps S14 and S15, the second display electrode 13b and the first electrochromic layer 14b are formed. Steps S14 and S15 can be performed similarly to steps S11 and S12.

Formation of counter electrode

In step S16, the counter electrode 15 is formed on the counter substrate 12 by vacuum deposition methods such as vapor deposition, sputtering and ion plating.

Fixation of the board

In step S17, the display substrate on which the counter substrate 12, on which the counter electrode 15 is formed, forms various layers from the electrolyte 20 including particles for the white reflective layer 21 to the first insulating layer 22 is formed. Fix to (11). Specifically, the display substrate 11 and the opposing substrate 12 are fixed to each other through the spacers 18 forming the cells 19. The cell 19 is then vacuum injected with an electrolyte solution 20 comprising particles for the white reflective layer 21 through an opening (not shown) in the cell 19. Then, the opening is hermetically sealed. The white reflective layer 21 may be formed by applying a resin dispersion of white pigment particles to the counter electrode 15.

Alternatively, the polymer electrolyte and the UV curable ink may be mixed, and the mixture may be applied to the display substrate 11 or the counter substrate 12 according to a predetermined pattern by screen printing or ink jet printing. Then, the display substrate 11 and the opposing substrate 12 are fixed to each other so that their electrodes face each other. Then, after the space between the substrates is filled with the electrolyte solution, the UV curable ink is irradiated with UV light to cure the UV curable ink, and the display substrate and the counter substrate are fixed to each other.

Embodiment 2

8 to 10, an image display device 30 according to another embodiment of the present invention will be described. The image display device 30 includes the electrochromic display device 10 according to the first embodiment. Specifically, the image display device 30 includes a plurality of electrochromic display devices 10 and uses it as an electrochromic display element 31 for displaying individual pixels. The electrochromic display element 31 can maintain a color development state or a discoloration state for a long time, so that the image display device 30 can maintain an image display state or an image non-display state for a long time.

The image display device 30 can be used as a reflective display device such as electronic paper.

8 is a schematic cross-sectional view of the image display device 30. The image display device 30 includes a display substrate 11 and an opposing substrate 12. 9 is a schematic perspective view of the display substrate 11. On the opposing substrate 12, a plurality of opposing electrodes 15 is provided for each electrochromic display element 31. On the display substrate 11, the first display electrode 13a, the first electrochromic layer 14a, the insulating film 22, the second display electrode 13b, and the respective electrochromic display elements 31 are formed. The second electrochromic layer 14b is disposed. Each electrochromic display element 31 includes a set of first display electrodes 13a, a first electrochromic layer 14a, an insulating film 22, a second display electrode 13b, and a second electrochromic layer ( 14b). A plurality of electrochromic display elements 31 are disposed in the plane of the display substrate 11 in the form of a matrix.

The image display device 30 includes a white reflective layer 21 in the cell 19. The white reflective layer 21 may be formed by injecting an electrolyte 20 including white pigment particles dispersed in the cell 19. Alternatively, a resin dispersion of white pigment particles may be applied to the counter electrode 15 to form the white reflective layer 21. Also preferably, the polymer electrolyte may be formed in a pattern according to the matrix electrode shape as mentioned above. This last method may be more advantageous in terms of manufacturing costs.

Hereinafter, the driving method of the electrochromic display element 31 of the image display device 30 will be described. Various units or circuits may be used to apply an electric field to the electrochromic display element 31 of the image display device 30. For example, a known active matrix driving electrical circuit can be employed to drive the electrochromic display element 31 according to a known active matrix driving method. The active matrix driving electric circuit may include an electric circuit in which an electrode of the thin film transistor TFT as the active matrix driving element is connected to the electrochromic display element 31. This type of electric circuit can drive the individual electrochromic display elements 31 at high speed, which enables the image display device 30 to display fine resolution images at high speed.

Next, a driving circuit for driving the electrochromic display element 31 of the image display device 30 using the active matrix driving method will be described with reference to FIG. As shown in Fig. 10, the image display device 30 includes a plurality of electrochromic display elements 31; Thin film transistors 33a and 33b connected to the first and second display electrodes 13a and 13b of the plurality of electrochromic display elements 31, respectively; Conducting wires 34a and 34b arranged in the horizontal direction and connected to the gate electrodes of the thin film transistors 33a and 33b; And conducting wires 35a and 35b disposed in the vertical direction and connected to the source electrodes of the thin film transistors 33a and 33b. The drain electrode of the thin film transistor 33a is connected to the first display electrode 13a of the electrochromic display element 31. The drain electrode of the thin film transistor 33b is connected to the second display electrode 13b of the electrochromic display element 31. The counter electrode 15 of the electrochromic display element 31 has a constant potential equal to the ground potential.

In the image display device 30 shown in FIG. 10, when a voltage is applied to one of the conductive wires 34a in the horizontal direction and to one of the conductive wires 35a in the vertical direction, the voltage is selected by the selected conductive wires 34a and 35a. It is applied to the gate electrode of the thin film transistor 33a connected to the thin film transistor 33a, so that the resistance between the source electrode and the drain electrode is reduced. As a result, a voltage is applied to the first display electrode 13a of the electrochromic display element 31 connected to the thin film transistor 33a. This causes the first electrochromic compound included in the electrochromic display element 31 to develop a predetermined color.

Similarly, when a voltage is applied to one of the conductors 34b in the horizontal direction and to one of the conductors 35b in the vertical direction, the voltage crosses the selected second display electrode 13b and the selected counter electrode 15. Is approved. This causes the second electrochromic compound included in the corresponding electrochromic display element 31 to develop a predetermined color. By these operations, a pixel located between the selected display electrode and the selected counter electrode is moved to a color due to the first electrochromic alone, a color due to the second electrochromic compound alone, or both the first and second electrochromic compounds. You can make the color develop.

Therefore, by selectively applying a voltage between the first and / or second display electrodes 13a and 13b and the counter electrode 15, the image display device 30 can display a predetermined image.

In order to maintain the color developed for an extended duration, there should be no low resistance portion between the selected display electrode and another display electrode or counter electrode. That is, the selected display electrode must be electrically insulated from other electrodes. Such electrical insulation makes it possible to prevent the discharge of the charge from the electrochromic compound through the electrode or the low resistance portion, or the injection of the discharge discharged from the electrochromic compound through the low resistance portion or the electrode. In this way, color retention time can be improved.

Preferably, when colorizing the display electrode, a discoloration voltage can first be applied to each of the display electrodes, and then the electrochromic layer can be colored one layer at a time by the color driving method described above. This application of the bleaching voltage to the display electrode can initiate the charged state (redox reaction state) of the electrochromic compound. Thereafter, color can be developed one by one. In this way, the color development / coloring operation of the individual electrochromic layers can be controlled with high reproducibility.

The redox reaction state of each electrochromic layer can be controlled to an intermediate state between an oxidation state in which all electrochromic particles are completely oxidized and a reduction state in which all electrochromic particles are fully reduced. This intermediate state allows the electrochromic layer to develop an intermediate color between the colored and bleached states.

The electrochromic layer can be controlled to be in an intermediate state by controlling the product of the voltage applied to the display electrode corresponding to the specific electrochromic layer and the time (that is, by controlling the amount of injected or emitted charge). In this case, the intermediate color can be controlled by continuously changing the applied voltage and time. Alternatively, the intermediate color can be controlled by changing the number of application of voltage pulses having a predetermined maximum voltage value and a predetermined pulse width.

Therefore, according to the second embodiment of the present invention, the stacked layers of the display electrode and the electrochromic layer are arranged in a matrix form in the plane of the substrate of the image display device 30, so that the image display device 30 displays various images. Do it.

The first display electrode 13a and the second display electrode 13b on the display substrate 11, respectively, so that the thin film transistors 33a and 33b do not reduce the visibility of the color developed by the electrochromic display element 31. The thin film transistors 33a and 33b connected to the opposing substrate 12 may be formed.

Although the image display device 30 has been described as including two display electrodes and two electrochromic layers disposed on the display electrodes, the number of layers and / or electrochromic layers of the display electrodes may be three or more.

Example 1

Formation of display electrode and electrochromic layer

After manufacturing the glass substrate measured by 30 mm x 30 mm, an ITO film was formed in the 16 mm x 23 mm area | region on the upper surface of a glass substrate by sputtering to about 100 nm thickness, and the 1st display electrode was formed. The sheet resistance between the electrode ends of the first display electrode was about 200 Ω.

The glass substrate on which the first display electrode was formed was coated with SP210 (available from Showa Titanium Co., Ltd.) as a titanium oxide nanoparticle dispersion by spin coating, followed by annealing at 120 ° C. for 15 minutes to form titanium dioxide. A particle film was formed. Then, a coating solution was prepared by mixing 5% by weight of 2,2,3,3-tetrafluoropropanol solution of the viologen compound according to the formula (4) and the aforementioned SP210 at a ratio of 2.4 / 4.

The coating solution was applied to the glass substrate by spin coating, and then annealed at 120 ° C. for 10 minutes to form a first electrochromic layer containing titanium dioxide particles and an electrochromic compound.

Next, on the glass substrate on which the first electrochromic layer was formed, 0.1 wt% ethanol solution of poly-N-vinyl amide and 0.5 wt% aqueous solution of polyvinyl alcohol were applied by spin coating to form a protective layer. . Subsequently, a film of ZnS-SiO _{2 having} a composition ratio of 8/2 was formed by sputtering to form an inorganic insulating layer with a film thickness in the range of 25 to 150 nm. Further, an ITO film of ZnS-SiO ₂ was formed by sputtering to a thickness of about 100 nm in a 10 mm x 20 mm region of the inorganic insulating layer on the surface of the glass substrate to form a second display electrode. The sheet resistance between the ends of the second display electrode was about 200 Ω.

On the glass substrate on which the second display electrode was formed, SP210 (Showa Titanium Co., Ltd.) as a dispersion of titanium dioxide nanoparticles was further applied by spin coating, followed by annealing at 120 ° C. for 15 minutes to form dioxide. Titanium particle film was formed.

A coating solution was prepared by mixing 1 wt% 2,2,3,3-tetrafluoropropanol solution and SP210 in a ratio of 2.4 / 4 of a viologen compound represented by the following formula (5).

After the coating solution was applied by spin coating, annealing was performed at 120 ° C. for 10 minutes to form a second electrochromic layer including titanium dioxide particles and an electrochromic compound to complete the display substrate.

Formation of counter electrode

Apart from the glass substrate, a glass substrate measuring 30 mm x 30 mm was produced, and a transparent conductive thin film of tin oxide was formed on the entire upper surface of the glass substrate. A solution was prepared by adding 25 wt% 2-ethoxyethyl acetate to CH10 (available from Jujo Chemical Co., Ltd.) as a thermosetting conductive carbon ink. The solution was applied to the upper surface of the glass substrate while forming a transparent conductive thin film of tin oxide thereon by spin coating. This was followed by annealing at 120 ° C. for 15 minutes to complete the counter substrate.

Assembly of Electrochromic Display

The display substrate and the opposing substrate were fixed to each other through a spacer having a length of 75 μm to form a cell. An electrolyte solution was prepared by dispersing 35 wt% titanium dioxide particles (manufactured by Ishihara Sangyo Kaisha, Ltd.) having a primary particle diameter of 300 nm in a propylene carbonate solution in which 0.1 M of perchlorate chloride was dissolved. The electrolyte solution was placed in the cell in a hermetically sealed manner to obtain the electrochromic display device 10e shown in FIG.

11A, 11B and 11C show the electrochromic display device 10e according to the first embodiment. 11A, 11B, and 11C are plan views of the electrochromic display device 10e, cross-sectional views taken along the line A-A of FIG. 11A, and cross-sectional views taken along the line B-B of FIG. 11A, respectively.

11B and 11C, the electrochromic display device 10e includes a first display electrode 13a (ITO1), a first electrochromic layer 14a (EC1), an insulating layer 22a, and a second display electrode. (13b) (IT02) and the second electrochromic layer 14b (EC2). As shown in FIG. 11A, the electrochromic display apparatus 10e has a center region (with a screen) in which all of ITO1, EC1, ITO2, and EC2 are stacked. The central area with this screen is referred to as the color / bleaching evaluation area used in the color / bleaching test, which will be described below.

Measurement of interelectrode resistance

The interelectrode resistance between the first display electrode 13a and the second display electrode 13b of the electrochromic display device 10e according to Example 1 was measured. 12 is a graph of the measurement results. As can be seen from the graph of Fig. 12, the film thickness of the inorganic insulating layer was set to 50 nm or more to obtain good insulation property (about 500 times more than the end-to-end sheet resistance of the display electrode).

Coloring / coloring test

The discoloration evaluation was performed by applying a voltage to the electrochromic display device 10e according to Example 1 while changing the film thickness of the inorganic insulating layer. The voltage was 1.7 V applied for 2 seconds. The display electrode was connected to the cathode, and the opposite electrode was connected to the anode.

When the thickness of the inorganic insulating layer is 50 nm or more and the inter-electrode resistance is 100 kΩ or more, blue color is emitted from the first display electrode independently of the application of voltage to the first or second display electrode, or the second display electrode is formed. Green color was developed from. In addition, it was possible to stably maintain the color developed.

When the thickness of the inorganic insulating layer is less than 50 nm and the inter-electrode resistance is less than 100 kΩ, when the voltage is applied to the first display electrode, the first display electrode is independently colored during the initial period of color development, but the second display electrode is As time progressed, color development gradually started, which prevented the stable development of color independently.

Example 2

An electrochromic display device (not shown) according to Example 2 was manufactured in the same manner as in Example 1, except that the formation of the titanium dioxide particle film was omitted. The interelectrode resistance between the first display electrode and the second display electrode of the electrochromic display device was measured. 12 shows the measurement results. As can be seen from FIG. 12, by setting the film thickness of the inorganic insulating layer to 75 nm or more, good insulation (about 500 times of the end-to-end sheet resistance of the display electrode) was obtained.

Coloring / coloring test

As in Example 1, color change / discoloration evaluation was performed by applying a voltage to the electrochromic display device according to Example 2 while changing the film thickness of the inorganic insulating layer. Specifically, the applied voltage was 1.7 V and the duration was 2 seconds. The display electrode was connected to the anode, and the opposite electrode was connected to the cathode.

When the thickness of the inorganic insulating layer is 75 nm or more and the inter-electrode resistance is 100 kΩ or more, blue color is emitted from the first display electrode independently of application of voltage to the first or second display electrode, or the second display electrode Green color was developed from. The color developed independently could be stably maintained.

When the thickness of the inorganic insulating layer is less than 75 nm and the inter-electrode resistance is less than 100 kΩ, when the voltage is applied to the first display electrode, the first display electrode is independently colored during the initial period of color development, but the second display electrode is Over time, its own color began to develop gradually, making it impossible to maintain a stable color independently.

Example 3

The material of the inorganic insulating layer of one device contains ZnS and the material of the inorganic insulating layer of another device contains ZnO-ZnO-In ₂ O ₃ -Ga ₂ O ₃ (60/23/10/7) and inorganic insulation Two electrochromic display devices (not shown) according to Example 3 were manufactured in the same manner as in Example 2, except that the layer thickness was 140 nm.

The interelectrode resistance between the first display electrode and the second display electrode of the electrochromic display device was measured. As a result, good insulation of about 10 MΩ was obtained in both electrochromic display devices.

Example 4

An electrochromic display device (not shown) was manufactured in the same manner as in Example 1, except that the display electrode and the electrochromic layer were manufactured by the following procedure.

Manufacture of Electrochromic Display

The glass substrate measured by 30 mm x 30 mm was produced. An ITO film was formed in a 16 mm by 23 mm area on the upper surface of the glass substrate by sputtering to a thickness of about 100 nm to form a first display electrode. The sheet resistance between the ends of the first display electrode was about 200 Ω.

The glass substrate on which the first display electrode was formed was coated with SP210 (Showa Titanium Co., Ltd.) as a titanium oxide nanoparticle dispersion by spin coating, followed by annealing at 120 ° C. for 15 minutes to form a titanium dioxide particle film. I was. The glass substrate was further coated with the coating liquid by spin coating. The coating solution contained a 1 wt% 2,2,3,3-tetrafluoropropanol solution of the viologen compound represented by the formula (5). An annealing treatment was then performed at 120 ° C. for 10 minutes to form a first electrochromic layer comprising titanium dioxide particles and an electrochromic compound.

On the glass substrate on which the first electrochromic layer was formed, a film of ZnS-SiO ₂ (composition ratio 8/2) was formed to a thickness of 140 nm by sputtering to form an inorganic insulating layer. Further, by sputtering, an ITO film was formed to a thickness of about 100 nm in a 10 mm by 20 mm region on the surface of the glass substrate to form a second display electrode. The sheet resistance between the ends of the second display electrode was about 200 Ω.

After further applying SP210 (Showa Titanium Co., Ltd.) as a titanium dioxide nanoparticle dispersion by spin coating on the glass substrate on which the second display electrode was formed, annealing treatment was performed at 120 ° C. for 15 minutes. Titanium dioxide particle film was formed. The glass substrate was further coated by spin coating with a coating solution containing a 1 wt% 2,2,3,3-tetrafluoropropanol solution of the viologen compound represented by the formula (4). Then, an annealing treatment was performed at 120 ° C. for 10 minutes to form a second electrochromic layer including titanium dioxide particles and an electrochromic compound to complete the display substrate. Then, similar steps to those described with reference to Example 2 were performed to obtain an electrochromic display device.

Measurement of interelectrode resistance

The interelectrode resistance between the first display electrode and the second display electrode of the electrochromic display device was about 10 MΩ, which suggested good insulation.

Coloring / coloring test

The electrochromic display device according to Example 4 was subjected to color development / discoloration evaluation in the same manner as in Example 2. Color development / discoloration evaluation is Otsuka Electronics Co., Ltd. It was accompanied by irradiation with diffused light using a manufactured LCD-5000 spectrophotometer. For voltage application, a FG-02 function generator (Toho Giken) was used. The applied voltage was 2.55 V, the duration of application was 100 ms, and the pulse interval was 10 ms when multiple pulses were applied.

The electrochromic display device according to Example 4 developed white color without applying voltage, and exhibited a white reflectance of about 50%. When the first display electrode is connected to the cathode and the opposite electrode is connected to the anode, the electrochromic display device displays green color when the pulse voltage is applied. When the second display electrode was connected to the negative electrode and the opposite electrode was connected to the positive electrode, the electrochromic display device developed blue color when the pulse voltage was applied. In addition, when the first and second display electrodes are connected to the cathode and the opposite electrode is connected to the anode, the electrochromic display device 10i has developed a black color when the pulse voltage is applied.

FIG. 13 is a graph showing the relationship between the number of pulse voltages applied to the first display electrode and the back reflectivity. 14 is a graph showing a relationship between the number of pulse voltages applied to the second display electrode and the back reflectivity. 15 is a graph showing the reflection spectrum during the development of blue color. 16 is a graph showing the reflection spectrum during green color development. 17 is a graph showing the reflection spectrum during black color development.

As can be seen in FIGS. 13 and 14, the white reflectance decreased continuously as the number of pulses applied when the pulse voltage was applied to the first display electrode and when the pulse voltage was applied to the second display electrode was increased. That is, as the number of pulse application increases, the color continues to darken, which suggests the possibility that an intermediate color can be displayed.

In the case of the application of the pulse voltage between the first display electrode and the opposite electrode, FIG. 15 shows an increase in reflectance at a wavelength of about 440 nm, which suggests a blue color development. In the case of applying the pulse voltage between the second display electrode and the counter electrode, FIG. 16 shows an increase in reflectance at a wavelength of about 490 nm, which suggests green color development. In the case of applying the pulse voltage between the first and second display electrodes and the counter electrode, FIG. 17 shows a general decrease in reflectance compared to FIGS. 15 and 16, which suggests black color development.

Therefore, multicolor display can be easily performed by selecting the first display electrode or the second display electrode for voltage application. By controlling the number of voltage pulse application times, the intermediate color can be displayed.

Example 5

Except for including three display electrode layers and three electrochromic layers, the electrochromic display device 10j shown in FIGS. 18A to 18C was manufactured in the same manner as in Example 1. FIG.

Formation of display electrode and electrochromic layer

A glass substrate measuring 30 mm x 30 mm was prepared, and an ITO film was formed in a 16 mm x 23 mm area on the upper surface of the glass substrate by sputtering to a thickness of about 100 nm to form a first display electrode. The sheet resistance between the ends of the first display electrode was about 200 Ω.

On the glass substrate on which the first display electrode was formed, SP210 (Showa Titanium Co., Ltd.) as a titanium oxide nanoparticle dispersion was coated by spin coating, followed by annealing at 120 ° C. for 15 minutes to make titanium dioxide particles. A film was formed. The glass substrate was then further coated with a coating solution by spin coating, which included a 1 wt% 2,2,3,3-tetrafluoropropanol solution of the viologen compound represented by the formula (5). . An annealing treatment was then performed at 120 ° C. for 10 minutes to form a first electrochromic layer comprising titanium dioxide particles and an electrochromic compound.

On the glass substrate on which the first electrochromic layer was formed, 0.1 wt% ethanol solution of poly-N-vinyl amide and 0.5 wt% aqueous solution of polyvinyl alcohol were further applied by spin coating to form a protective layer. Next, a sputtering film of ZnS-SiO _{2 having} a composition ratio of 8/2 was formed to a thickness of 140 nm to form an inorganic insulating layer. Further, an ITO film on the surface of the glass substrate was formed by sputtering to a thickness of about 100 nm in a 10 mm x 20 mm region in which an inorganic insulating layer of ZnS-SiO ₂ was formed thereon, thereby forming a second display electrode. The sheet resistance between the ends of the second display electrode was about 200 Ω.

The glass substrate on which the second display electrode was formed was further coated with SP210 (manufactured by Showa Titanium Co., Ltd.) as a titanium dioxide nanoparticle dispersion by spin coating, followed by annealing at 120 ° C. for 15 minutes to form titanium dioxide. A particle film was formed. Next, the glass substrate was spun into a coating solution comprising a mixture of 1 wt% 2,2,3,3-tetrafluoropropanol solution of the viologen compound represented by the formula (5) and a mixture of SP210 at a mixing ratio of 2.4 / 4. Coated by coating. This was followed by annealing at 120 ° C. for 10 minutes to form a second electrochromic layer comprising titanium dioxide particles and an electrochromic compound.

The glass substrate on which the first electrochromic layer was formed was coated by spin coating with a 0.1 wt% ethanol solution of poly-N-vinyl amide and a 0.5 wt% aqueous solution of polyvinyl alcohol to form a protective layer. Next, a sputtering film of ZnS-SiO _{2 having} a composition ratio of 8/2 was formed to a thickness of 140 nm to form an inorganic insulating layer. Further, an ITO film on the surface of the glass substrate was formed by sputtering to a thickness of about 100 nm in a 10 mm x 20 mm region where an inorganic insulating layer of ZnS-SiO ₂ was formed thereon, to form a third display electrode. The sheet resistance between the ends of the third display electrode was about 200 Ω.

The glass substrate on which the third display electrode was formed was further coated with SP210 (manufactured by Showa Titanium Co., Ltd.) as a titanium dioxide nanoparticle dispersion by spin coating, followed by annealing at 120 ° C. for 15 minutes to form titanium dioxide. A third electrochromic layer containing the particles was formed. The glass substrate on which the third electrochromic layer was formed was further coated by spin coating with a 0.1 wt% ethanol solution of poly-N-vinyl amide and a 0.5 wt% aqueous solution of polyvinyl alcohol to form a protective layer. Then, a film of ZnS-SiO _{2 having} a composition ratio of 8/2 was formed by sputtering at a film thickness of 35 nm to form an inorganic insulating layer.

18A, 18B, and 18C show the electrochromic display device 10j according to the fifth embodiment. 18A, 18B, and 18C are plan views of the electrochromic display device 10j, sectional views taken along the line A-A of FIG. 18A, and sectional views taken along the line B-B, respectively.

As shown in FIGS. 18B and 18C, the electrochromic display device 10j includes a first display electrode 13a (ITO1), a first electrochromic layer 14a (EC1), a first insulating layer 22a, Second display electrode 13b (ITO2), second electrochromic layer 14b (EC2), second insulating layer 22b, third display electrode 13c (ITO3) and third electrochromic layer 14c (EC3). As shown in FIG. 18A, the electrochromic display apparatus 10j has a center region (with a screen) in which all of ITO1, EC1, ITO2, EC2, ITO3, and EC3 are stacked. The central area with this screening is referred to as the color / bleaching evaluation area where the color / bleaching test, which will be described below, is performed.

Measurement of interelectrode resistance

The interelectrode resistance between the first display electrode and the second display electrode of the electrochromic display device 10j was about 10 MΩ, while the interelectrode resistance between the second display electrode and the third display electrode was about 0.5 MΩ.

Coloring / coloring test

The electrochromic display device 10j according to Example 5 was subjected to color evaluation with voltage application for 2 seconds so that a potential difference appeared between the display electrode and the counter electrode as shown in FIGS. 19A to 19C.

Specifically, in FIG. 19A, a voltage was applied such that ITO1 / EC1 had a potential of 0V while the counter electrode had a potential of 1.5V, and no voltage was applied to ITO2 / EC2 and ITO3 / EC3. In the case of Fig. 19B, voltage was applied such that ITO2 / EC2 had a potential of 0V while the counter electrode had a potential of 1.5V, and no voltage was applied to ITO1 / EC1 and ITO3 / EC3. In the case of Fig. 19C, voltage was applied such that ITO3 / EC3 had a potential of 0 V while the counter electrode had a potential of 1.5 V, and no voltage was applied to ITO1 / EC1 and ITO2 / EC2.

As a result, in Fig. 19, only the region of ITO1 / EC1 was colored. In the case of Fig. 19B, only the ITO2 / EC2 region is developed. In the case of Fig. 19C, only the region of ITO3 / EC3 was colored. Thus, the first, second and third display electrodes could be colored independently.

Example 6

The first electrochromate was prepared using a 2,2,3,3-tetrafluoropropanol solution containing 4 wt% of a terephthalic acid compound represented by the following formula (6) and 20 wt% of AMT10 titanium oxide particles (Tayca Corporation): An electrochromic display device (not shown) was manufactured in the same manner as in Example 1 except that the mixed layer was formed. Another difference from Example 1 is that the second, using 2,2,3,3-tetrafluoropropanol solution containing 4% by weight of the terephthalic acid compound represented by the following formula (7) and 20% by weight of AMT100 The electrochromic layer was formed.

The electrochromic display apparatus 10k comprises 35 wt% titanium oxide particles (manufactured by Ishihara Sangyo Kaisha, Ltd.) having a primary particle diameter of 300 nm in an electrolyte of dimethyl sulfoxide in which 0.1 M tetrabutylammonium perchlorate is dissolved. It was further different from Example 1 that it was dispersed in the solution.

The interelectrode resistance between the first display electrode and the second display electrode of the electrochromic display device 10k was about 10 MΩ, which suggests good insulation.

Coloring / coloring test

Coloring / coloring evaluation was performed for the electrochromic display device according to Example 6. Colorimetric / discoloration evaluation involved irradiating the electrochromic display device 10k with diffused light using an LCD-5000 spectrophotometer (Otsuka Electronics Co., Ltd.). For voltage application, a pulse of 4.5 V was provided for 100 ms using a FG-02 function generator (Toho Giken), and the pulse interval was 10 ms when multiple pulses were applied.

The electrochromic display device developed a white color without applying a voltage, suggesting a back reflectance of about 45%. When the first display electrode 13a is connected to the cathode and the opposite electrode 12 is connected to the anode, magenta is developed when the pulse electrode is applied. When the second display electrode 13b is connected to the cathode and the opposite electrode 12 is connected to the anode, yellow color is generated when the pulse voltage is applied. When the first and second display electrodes 13a and 13b are connected to the cathode and the opposite electrode 12 is connected to the anode, red color is generated when the pulse voltage is applied.

20 is a graph showing the reflection spectrum at the time of magenta color development. 21 is a graph showing the reflection spectrum at the time of yellow color development. In the case of FIG. 20, when a pulse voltage is applied between the first display electrode 13a and the counter electrode 12, the reflectance increases at wavelengths of about 420 nm and 600 nm or more, which suggests color development of magenta. In the case of FIG. 21, when a pulse voltage is applied between the second display electrode 13b and the counter electrode 12, the reflectance increases at a wavelength of about 500 to 600 nm, which suggests yellow color development.

Therefore, by selecting the first display electrode 13a or the second display electrode 13b for voltage application, multicolor display can be easily realized. By controlling the number of voltage pulse application times, the intermediate color can be displayed.

Example 7

An electrochromic display device (not shown) was manufactured in the same manner as in Example 4 except that the conditions for the manufacture of the counter electrode and the assembly of the electrochromic display device were different.

Formation of counter electrode

Apart from the substrate on which the display electrode is formed, a glass substrate measured by 30 mm x 30 mm was produced, and a transparent conductive thin film of tin oxide was formed on the entire upper surface of the glass substrate. The top surface of the glass substrate on which the transparent conductive thin film was formed was spin-coated to dissolve 20% by weight of a 2,2,3,3-tetrafluoropropanol dispersion [primary particle diameter of 30 nm] at a thickness of about 2 μm. Coated tin oxide particles (including Mitsubishi Materials Corporation). An annealing treatment was then performed at 120 ° C. for 15 minutes to form the counter electrode.

Manufacture of Electrochromic Display

PTC10 UV curable ink (Jujo Chemical Co., Ltd.), perchlorate chloride, propylene carbonate, and titanium oxide particles (Ishihara Sangyo Kaisha, Ltd.) having a primary particle diameter of 300 nm were weighed in 10/1/2/2. Mixing in the ratio produced electrolyte white ink.

Then, the electrolyte white ink was applied to the counter electrode prepared as described above in a pattern such that dots of 1 mm in diameter and about 5 μm in thickness were arranged at intervals from the center to the center of 2.5 mm.

Then, the display substrate was placed on the opposing substrate so that the display electrode and the electrochromic layer of the display substrate opposed the coating of the electrolyte white ink on the opposing substrate. After being left for 10 minutes, UV irradiation was performed to cure the electrolyte white ink to fix the display substrate on the opposite substrate.

Measurement of resistance between display electrodes

The interelectrode resistance between the first display electrode and the second display electrode of the electrochromic display device was measured. The resistance was about 10 MΩ, suggesting good insulation.

Coloring / coloring test

Color evaluation was performed by applying a voltage to the electrochromic display device according to the seventh embodiment. The applied voltage was 2.5 V and the application duration was 2 seconds. The display electrode was connected to the cathode while the opposite electrode was connected to the anode.

As a result, the first display electrode and the second display electrode were able to independently develop blue and green colors. It was also possible to develop only the patterned electrolyte white ink portion.

Example 8

Except that the viologen compound represented by the general formula (4) was replaced with the viologen compound represented by the following general formula (8) in which the furan structure as the heterocyclic compound was introduced between the pyridine ring alkyl cation structures. An electrochromic display device was manufactured in the same manner as in 1.

Another exception was that the viologen compound represented by the formula (5) was replaced by the viologen compound represented by the following formula (9), in which a thiophene structure as a heterocyclic compound was introduced between a pyridine ring alkyl cation structure. Will be.

When a voltage was applied to the display electrode of the electrochromic display device, the first and second display electrodes could each independently develop magenta and yellow color. In addition, the color once developed independently could be stably maintained.

Comparative Example 1

An electrochromic display device according to Comparative Example 1 was manufactured in the same manner as in Example 4 except that the insulating layer was not formed.

The interelectrode resistance between the first display electrode and the second display electrode of the electrochromic display device was measured. The measurement showed a resistance of about 200 Ω, suggesting poor insulation.

The electrochromic display device according to Comparative Example 1 was also subjected to the color development / discoloration test in the same manner as in Example 4. When the second display electrode was connected to the cathode and the opposite electrode was connected to the anode, the electrochromic display device developed black color at the voltage of the pulse applied, which was independently blue due to the first electrochromic layer, and the second electrochromic. This indicates that the mixed layer failed to develop green color.

Although the invention has been described in detail with reference to specific embodiments, variations and modifications are within the scope and spirit of the invention as described and defined in the following claims.

The present application is based on Japanese Priority Application No. 2009-112006, filed May 1, 2009, which is hereby incorporated by reference in its entirety.

Claims (14)

A display substrate;
An opposite substrate disposed opposite the display substrate;
An opposite electrode disposed on the opposite substrate;
A plurality of display electrodes isolated from each other and disposed between the display substrate and the opposite electrode;
A plurality of electrochromic layers disposed over corresponding display electrodes; And
Electrolyte disposed between display electrode and counter electrode
An electrochromic display device comprising:
The electrical resistance between one display electrode and another display electrode is greater than the electrical resistance of one or the other display electrode,
And at least one display electrode disposed between the display electrode closest to the display substrate and the opposite electrode is permeable to the electrolyte. The electrochromic display device of claim 1, wherein the electrochromic layer comprises an electrochromic compound and metal oxide particles. The electrochromic display device according to claim 1, further comprising a reflective layer disposed between the electrochromic layer closest to the opposing substrate and the opposing electrode or on the opposing substrate side opposite the opposing electrode. The electrochromic display device of claim 1, wherein the electrolyte is patterned in the form of a matrix. The electrochromic display device of claim 1, further comprising an insulating layer between the display electrodes to mutually insulate the display electrodes. The electrochromic display device according to claim 1, wherein one of the electrochromic layers having the highest threshold voltage for color development is disposed corresponding to the display electrode closest to the display substrate. The electrochromic display device according to claim 1, wherein one of the electrochromic layers having the highest threshold voltage for discoloration is disposed corresponding to the display electrode closest to the display substrate. The electrochromic display device according to claim 1, wherein the electrochromic layer disposed on the corresponding display electrode is configured to color different colors. The electrochromic display device according to claim 1, wherein at least one of the electrochromic layers comprises a viologen compound represented by the following general formula (1):

In the above formula, R 1, R 2 and R 3 are independently an alkyl or aryl group having 1, 2, 3 or 4 carbon atoms which may include substituents, and one of R 1 and R ₂ is COOH, PO (OH) ₂ and Si (OC). _k H _{2k + 1} ) ₃ ; X is a monovalent anion; n is 0, 1 or 2; m is 0, 1, 2, 3 or 4; k is 0, 1 or 2; The electrochromic display device according to claim 1, wherein at least one of the electrochromic layers comprises a terephthalic acid compound represented by the following general formula (2):

In the above formula, R 4, R 5 and R 6 are alkyl, alkoxy or aryl groups having 1, 2, 3 or 4 carbon atoms, and one of R 4 and R 5 is COOH, PO (OH) ₂ and Si (OC _k H _{2k + 1} ) Is selected from ₃ ; q is 1 or 2; p is 0, 1, 2, 3 or 4; k is 0, 1 or 2; The electrochromic display device according to claim 1, wherein at least one of the electrochromic layers comprises a compound represented by the following formula (3), wherein a heterocyclic compound derivative structure is positioned between two pyridine ring alkyl cation structures.

In the above formula, R 1, R 2 and R 3 are independently an alkyl or aryl group having 1, 2, 3 or 4 carbon atoms which may include substituents, and one of R 1 and R ₂ is COOH, PO (OH) ₂ and Si (OC). _k H _{2k + 1} ) ₃ ; X is a monovalent anion; n is 0, 1 or 2; m is 0, 1 or 2; k is 0, 1 or 2; A is a heterocyclic compound derivative. The electrochromic display device according to claim 9, wherein all of the electrochromic layers include a viologen compound represented by the following general formula (1):

In the above formula, R 1, R 2 and R 3 are independently an alkyl or aryl group having 1, 2, 3 or 4 carbon atoms which may include substituents, and one of R 1 and R ₂ is COOH, PO (OH) ₂ and Si (OC). _k H _{2k + 1} ) ₃ ; X is a monovalent anion; n is 0, 1 or 2; m is 0, 1, 2, 3 or 4; k is 0, 1 or 2; The electrochromic display device according to claim 10, wherein all of the electrochromic layers include a terephthalic acid compound represented by the following general formula (2):

In the above formula, R 4, R 5 and R 6 are alkyl, alkoxy or aryl groups having 1, 2, 3 or 4 carbon atoms, and one of R 4 and R 5 is COOH, PO (OH) ₂ and Si (OC _k H _{2k + 1} ) Is selected from ₃ ; q is 1 or 2; p is 0, 1, 2, 3 or 4; k is 0, 1 or 2; The electrochromic display device according to claim 11, wherein all of the electrochromic layers include a compound represented by the following formula (3), wherein a heterocyclic compound derivative structure is positioned between two pyridine ring alkyl cation structures.

In the above formula, R 1, R 2 and R 3 are independently an alkyl or aryl group having 1, 2, 3 or 4 carbon atoms which may include substituents, and one of R 1 and R ₂ is COOH, PO (OH) ₂ and Si (OC). _k H _{2k + 1} ) ₃ ; X is a monovalent anion; n is 0, 1 or 2; m is 0, 1 or 2; k is 0, 1 or 2; A is a heterocyclic compound derivative.

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