JP2010160370A - Electrochromic display element and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochromic display element that is an inexpensive reflection type color display element having high image quality, and also to provide a display device using the electrochromic display element. <P>SOLUTION: The electrochromic display element has: a first medium 10 where at least a counter electrode 12, a reflection layer 13, a first display layer 14 containing electrochromic composition, and a first display electrode 15 are layered in this order on a counter substrate 11; and a second medium 20 where at least a second display electrode 22 and a second display layer 23 containing electrochromic composition that develops different color from the first display layer 14 are layered in this order on a display substrate 21. A principal plane on the first display electrode 15 side of the first medium 10 and a principal plane on the second display layer 23 side of the second medium 20 are faced with each other, with a space therebetween, and the space between both media is filled with electrolyte 30. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a display element, and more particularly to an element configuration of a multicolor display using an electrochromic compound.

  In recent years, electronic paper has been actively developed as an electronic medium replacing paper. The characteristics necessary for electronic paper compared to conventional displays such as CRTs and liquid crystal displays are reflective display elements, high white reflectance and high contrast ratio, high-definition display, display In other words, it has a memory effect, can be driven at a low voltage, is thin and light, and is inexpensive. In particular, white reflectance and contrast ratio equivalent to those of paper are required as display characteristics, and it is not easy to develop a display device having these characteristics. In addition, the conventional display and paper medium naturally display full color, and there is a great demand for colorization of electronic paper.

  As a technique of electronic paper that has been proposed so far, for example, a medium in which a color filter is formed on a reflective liquid crystal element has already been commercialized. However, since a polarizing plate is used, light utilization efficiency is low and dark. Only white display is possible. Furthermore, since black cannot be displayed, the contrast ratio is also poor.

  In addition, there is an electrophoretic method based on the principle of moving charged white particles and black particles with an electric field as a bright reflective display element. In this method, it is realistic to completely invert white particles and black particles. It is difficult to satisfy high white reflectance and high contrast ratio at the same time. Patent Documents 1 and 2 disclose a reflective color display medium in which a color filter is formed on an electrophoretic element. However, even if a color filter is formed on a display medium having a low white reflectance and a low contrast ratio, good image quality is achieved. It is clear that cannot be obtained.

  Further, Patent Documents 3 and 4 disclose an electrophoretic element that performs colorization by moving particles colored in a plurality of colors, but in principle, the above-described problem is achieved even if these methods are used. This is not a solution, and it is impossible to satisfy a high white reflectance and a high contrast ratio at the same time.

  By the way, the phenomenon of reversible color change and reversible color change when voltage is applied is called electrochromism. A display element utilizing the coloring / decoloring of an electrochromic compound that causes such a phenomenon is a reflective display element, and can have high white reflectance, a memory effect, and can be driven at a low voltage. , Cited as a candidate for electronic paper. Patent Documents 5 to 7 report a device in which an organic electrochromic compound is supported on the surface of semiconductor fine particles such as titanium oxide. This element has a higher white reflectance than the above-described liquid crystal element and electrophoretic element, and a certain degree of white reflectance can be secured even if a color filter is provided. However, it is difficult to obtain a sufficiently high-quality color display simply by providing a color filter in a monochrome electrochromic display element.

  In Japanese Patent Application Laid-Open No. H10-228867, the present inventors have disclosed a threshold voltage for entering a color development state or a threshold voltage for entering a decoloring state or a necessary charge amount or a desired color density for color development to a desired color density. It was shown that reflection type full-color display is possible by laminating three types of electrochromic compositions having different charge amounts for decoloring. The method shown here is the method that enables the highest-quality reflective full-color display, but it is difficult to ensure a sufficient difference in the threshold voltage and required charge amount of each electrochromic composition laminated on the display electrode. It was necessary to drive by precisely controlling the applied voltage, current amount, and application time. Therefore, there is a possibility that the driving portion is expensive.

JP 2003-161964 A JP 2004-361514 A Japanese translation of PCT publication No. 2004-520621 Special table 2004-536344 gazette Special table 2001-510590 gazette JP 2002-328401 A JP 2004-151265 A JP 2006-106669 A

  The present invention has been made in view of the above problems in the prior art, and provides an electrochromic display element which is a reflective color display element with high image quality and is inexpensive, and a display device using the electrochromic display element. For the purpose.

The present invention provided to solve the above problems is as follows.
[1] As a display layer / electrode stack in which a display layer containing an electrochromic composition and a display electrode are stacked in this order on a counter electrode / reflection layer stacked on a substrate, the first display layer / A display including an electrode laminate, a first display layer / electrode laminate (a is an integer of 0 or 2 or more), a display medium, a display electrode, and an electrochromic composition on a transparent substrate As an electrode / display layer stack in which layers are stacked in this order, layers are stacked in order from the first electrode / display layer stack to the b-th electrode / display layer stack (b is an integer of 0 or 2 or more). Each of the display layers includes an electrochromic composition that develops a color different from that of the other display layers, and the main surface on the display electrode side of the outermost layer of the first medium And the main surface on the display layer side of the outermost layer of the second medium, An electrochromic display element, wherein the electrochromic display element is disposed so as to face each other at an interval, and an electrolyte is filled between the first medium and the second medium.
[2] The electrochromic display element according to [1], wherein all of the display electrodes are transparent electrodes.
[3] The above [1] or [2], wherein an insulating layer is provided between the two adjacent display layers / electrode stacks and / or between the two adjacent electrode / display stacks. ] The electrochromic display element of description.
[4] A first medium in which at least a counter electrode, a reflective layer, a first display layer containing an electrochromic composition, and a first display electrode are laminated in this order on a substrate, and a first medium provided on a transparent substrate. The second display layer to the d-th display layer (d is an integer of 3 or more) containing the electrochromic composition that develops a color different from that of the other display layers are sequentially stacked on the second display electrode. Each of the electrochromic compositions in the second display layer to the d-th display layer of the second medium has at least a coloring threshold voltage, a decoloring threshold voltage, a charge amount necessary for coloring, One of the charge amounts necessary for erasing is different, and the main surface on the first display electrode side of the outermost layer of the first medium is spaced from the main surface on the d-th display layer side of the outermost layer of the second medium. Between the first medium and the second medium. An electrochromic display element characterized by being filled with an electrolyte.
[5] The electrochromic display element according to [4], wherein the first display electrode and the second display electrode are transparent electrodes.
[6] The electrochromic according to any one of [1] to [5], wherein an insulating layer is provided between the counter electrode and the reflective layer and / or between the reflective layer and the first display layer. Display element.
[7] The electrochromic display element according to any one of [1] to [6], wherein the electrochromic composition includes conductive or semiconductive fine particles carrying an organic electrochromic compound on a surface thereof. .
[8] The electrochromic display element according to any one of [1] to [7], wherein the electrochromic composition contains a viologen-based electrochromic compound.
[9] The electrochromic display element according to any one of [1] to [8], wherein the electrochromic composition contains a phthalic acid-based electrochromic compound.
[10] A display device using the electrochromic display element according to any one of [1] to [9].

As an effect of the present invention, the invention according to claim 1 has a structure in which a display layer is provided on each of the transparent substrate (display substrate) side and the counter electrode side, and can be provided at a low cost as a color display element. At this time, when a structure having three display layers on each of the transparent substrate (display substrate) side and the counter electrode side is provided, a high-quality color display element can be provided at low cost.
According to the invention of claim 2, since the display electrode is a transparent electrode, it can be provided at a low cost as a high-quality color display element exhibiting a high white reflectance.
According to the invention of claim 3, the production yield can be improved by including the insulating layer, and it can be provided at a lower cost as a high-quality color display element.
According to invention of Claim 4, it is a structure with a display layer in each of a transparent substrate (display substrate) side and a counter electrode side, and can be provided at low cost as a color display element. At this time, when a structure having three display layers on each of the transparent substrate (display substrate) side and the counter electrode side is provided, a high-quality color display element can be provided at low cost.
According to the invention of claim 5, since the display electrode is a transparent electrode, it can be provided at a low cost as a high-quality color display element exhibiting a high white reflectance.
According to the invention of claim 6, by including an insulating layer, the production yield can be improved and it can be provided at a lower cost as a high-quality color display element.
According to the invention of claim 7, it is possible to provide a high-quality color display element with high-speed response and low power consumption at low cost.
According to the eighth aspect of the invention, it is possible to provide a high-quality color display element with high speed response, low power consumption, and high durability at low cost.
According to invention of Claim 9, a high quality full color display element can be provided at low cost.
According to the invention of claim 10, it is possible to provide a reflection type high quality full color display device at low cost.

It is sectional drawing which shows the structural example (1) in 1st Embodiment of the electrochromic display element which concerns on this invention. It is sectional drawing which shows the structural example (2) in 1st Embodiment of the electrochromic display element which concerns on this invention. It is sectional drawing which shows the structural example in 2nd Embodiment of the electrochromic display element which concerns on this invention. It is sectional drawing which shows the structure of the display apparatus which concerns on this invention. FIG. 5 is a schematic diagram illustrating a configuration of a drive circuit of the display device in FIG. 4. 3 is a schematic diagram illustrating a configuration of a first medium in Embodiment 1. FIG. FIG. 3 is a schematic diagram illustrating a configuration of a second medium in the first embodiment. 6 is a schematic diagram illustrating a configuration of a second medium in Embodiment 2. FIG. 10 is a schematic diagram illustrating a configuration of a second medium in Embodiment 3. FIG.

In Japanese Patent Application No. 2008-174866, the inventors have shown a method of performing reflective full-color display by laminating three display electrodes and three types of electrochromic compositions corresponding to the display substrate. This method is also a useful method capable of high-quality full-color display. However, since many layers are stacked on the display substrate, there is a concern that the yield may deteriorate in the manufacturing process, which may increase the manufacturing cost. was there.
Therefore, the present inventors have intensively studied to solve this problem, and have reached the present invention. Below, the structure of the electrochromic display element and display apparatus which concern on this invention is demonstrated.

In the first embodiment of the electrochromic display element according to the present invention, a display layer containing an electrochromic composition and a display electrode are laminated in this order on a counter electrode / reflective layer laminated on a substrate. As a display layer / electrode laminate, a first medium that is laminated in order from the first display layer / electrode laminate to the a-th display layer / electrode laminate (a is an integer of 0 or 2 or more), and a transparent substrate In addition, as the electrode / display layer laminate in which the display electrode and the display layer containing the electrochromic composition are laminated in this order, the first electrode / display layer laminate to the b electrode / display layer laminate (b is Each of the display layers includes an electrochromic composition that develops a color different from that of the other display layers, respectively. The outermost surface of the first medium The main surface on the display electrode side and the main surface on the display layer side of the outermost layer of the second medium are arranged to face each other with a space therebetween, and an electrolyte is filled between the first medium and the second medium. It is characterized by. Here, the values of a and b may be set so that the number of colors necessary and sufficient for displaying an image or the like as a display element is not particularly limited. For example, a + b ≦ 6 or a + b = 0. , 2.
One configuration example of this embodiment is shown in FIG. FIG. 1 shows a case where a = 0 and b = 0.

FIG. 1 is a cross-sectional view showing a configuration example (1) of the electrochromic display element according to the first embodiment of the present invention.
As shown in FIG. 1, the electrochromic display element 100 includes at least a counter electrode 12, a reflective layer 13, a first display layer 14 containing an electrochromic composition, and a first display electrode 15 on a counter substrate (substrate) 11. A first medium 10 sequentially laminated, and a second display layer 23 containing an electrochromic composition that develops a color different from at least the second display electrode 22 and the first display layer 14 on a display substrate (transparent electrode) 21. A second medium 20 stacked in this order, and the main surface of the first medium 10 on the first display electrode 15 side and the main surface of the second medium 20 on the second display layer 23 side are opposed to each other with a gap therebetween. The electrolyte 30 is filled between the two media.

  Note that a laminate of the first display layer 14 and the first display electrode 15 is called an eleventh display layer / electrode laminate 16, and a laminate of the second display electrode 22 and the second display layer 23 is the twenty-first electrode / electrode laminate. The display layer laminate 24 is referred to. The distance between the main surface of the first medium 10 on the first display electrode 15 side and the main surface of the second medium 20 on the second display layer 23 side is a spacer provided between the counter substrate 11 and the display substrate 21. 40.

(Display operation of electrochromic display element 100)
In the electrochromic display element 100, when a desired voltage is applied between the first display electrode 15 and the counter electrode 12, the electrochromic compound contained in the first display layer 14 that is in contact with the first display electrode 15 is colored / Can be decolored. At this time, since there is a gap between the first display electrode 15 and the second display layer 23, charge transfer does not occur, and the second display layer 23 does not react at all.

  On the other hand, when a desired voltage is applied between the second display electrode 22 and the counter electrode 12, the electrochromic compound contained in the second display layer 23 in contact with the second display electrode 22 can be colored / decolored. it can. At this time, since there is a gap between the second display electrode 22, the first display electrode 15, and the first display layer 14, no charge transfer occurs, and the first display layer 14 does not react at all.

  Therefore, the first display layer 14 and the second display layer 23 can be individually colored / decolored. In addition, since the electrochromic compound has memory properties, if the second display layer 23 is colored after the first display layer 14 is colored, the colors of both the first display layer 14 and the second display layer 23 are mixed. Can be displayed. As described above, the display element 100 can perform color display.

  Therefore, according to this structure, a plurality of display layers are separately provided on each of the counter substrate 11 side (first medium 10 side) and the display substrate 21 side (second medium 20 side), so that the yield can be improved. Therefore, a color display element can be provided at a low cost.

FIG. 2 is a sectional view showing a configuration example (2) in the first embodiment of the electrochromic display element according to the present invention. FIG. 1 shows a case where a = 0 and b = 2.
As shown in FIG. 2, the electrochromic display element 200 includes at least a counter electrode 12, a reflective layer 13, a first display layer 14 containing an electrochromic composition, and a first display electrode 15 on a counter substrate (substrate) 11. A first medium 10 sequentially laminated, and a second display layer 23a containing an electrochromic composition that develops a color different from at least the second display electrode 22a and the first display layer 14 on a display substrate (transparent substrate) 21; A second medium 20A in which a third display electrode 22b and a third display layer 23b containing an electrochromic composition that develops a different color from the first display layer 14 and the second display layer 23a are stacked in this order. The main surface of the first medium 10 on the first display electrode 15 side and the main surface of the second medium 20A on the third display layer 23b side are opposed to each other, and the electrolyte 30 is interposed between the two media. It is one that is Hama.

  Note that a laminate of the first display layer 14 and the first display electrode 15 is called an eleventh display layer / electrode laminate 16, and a laminate of the second display electrode 22a and the second display layer 23a is a twenty-first electrode / electrode laminate. The display layer laminate 24a is referred to as a laminate of the third display electrode 22b and the third display layer 23b, and is referred to as a 22nd electrode / display layer laminate 24b. The distance between the main surface of the first medium 10 on the first display electrode 15 side and the main surface of the second medium 20A on the third display layer 23b side is a spacer provided between the counter substrate 11 and the display substrate 21. 40.

(Display operation of electrochromic display element 200)
In the electrochromic display element 200, when a desired voltage is applied between the first display electrode 15 and the counter electrode 12, the electrochromic compound contained in the first display layer 14 in contact with the first display electrode 15 is colored / Can be decolored. At this time, since the first display electrode 15 is not in contact with the second display electrode 22a, the second display layer 23a, the third display electrode 22b, and the third display layer 23b, charge transfer does not occur, and the second display layer 23a and the third display layer 23b do not react at all.

  On the other hand, when a desired voltage is applied between the second display electrode 22a and the counter electrode 12, the electrochromic compound contained in the second display layer 23a in contact with the second display electrode 22a can be colored / decolored. . At this time, the second display electrode 22a, the first display electrode 15, the first display layer 14, the third display electrode 22b, and the third display layer 23b are not in contact with each other, so that no charge transfer occurs and the first display layer 14. The third display layer 23b does not react at all.

  Similarly, when a desired voltage is applied between the third display electrode 22b and the counter electrode 12, the electrochromic compound contained in the third display layer 23b in contact with the third display electrode 22b can be colored / decolored. it can. At this time, the third display electrode 22b, the first display electrode 15, the first display layer 14, the second display electrode 22a, and the second display layer 23b are not in contact with each other, so that no charge transfer occurs and the first display layer 14. The second display layer 23a does not react at all.

  Based on the above operation principle, the first display layer 14, the second display layer 23a, and the third display layer 23b can be individually colored / decolored. Further, since the electrochromic compound has a memory property, various mixed colors can be displayed using the colors of the first display layer 14, the second display layer 23a, and the third display layer 23b. If the first display layer 14, the second display layer 23 a, and the third display layer 23 b use materials that develop the three primary colors yellow, magenta, and cyan, respectively, high-quality full-color display by subtractive color mixture can be performed. .

  The present inventors have proposed a full-color display method using three display electrodes and three display layers in Japanese Patent Application No. 2008-174866 described above. The difference from the present invention is that, in Japanese Patent Application No. 2008-174866, all of the display electrodes and the display layer are laminated on the display substrate side, whereas in the present invention, a plurality of display electrodes and a part of the display layer are provided. For example, the first display electrode 15 and the first display layer 14 are divided on the counter substrate side. In general, when a multilayer structure element is manufactured, the probability of failure increases and the yield decreases as the number of layers increases. In addition, the tact time of production is greatly influenced by the slowest process. Therefore, rather than forming six layers on one substrate, dividing one layer (for example, the first medium 10) into four layers and the other (for example, the second medium 20A) into two layers increases the yield, and the tact time is also reduced. Shorter. Therefore, an equivalent high-quality full color display can be obtained and the cost can be reduced.

Next, in the second embodiment of the electrochromic display element according to the present invention, at least a counter electrode, a reflective layer, a first display layer including an electrochromic composition, and a first display electrode are stacked in this order on a substrate. The second display layer to the d-th display layer containing an electrochromic composition that develops a different color from the other display layers on the first medium and the second display electrode provided on the transparent substrate. d is an integer greater than or equal to 3), and the electrochromic compositions in the second display layer to the d-th display layer of the second medium are mutually at least The main surface on the first display electrode side of the outermost layer of the first medium and the second medium are different in any one of the coloring threshold voltage, the decoloring threshold voltage, the charge amount necessary for color development, and the charge amount necessary for decoloration The outermost d-th display layer The principal surface of, but are oppositely spaced apart, said first medium, in which the electrolyte between the second medium is characterized by comprising been filled. Here, the value of d may be set so that the number of colors necessary and sufficient for displaying an image or the like as a display element is not particularly limited. For example, d ≦ 6 or d = 3. . Note that a structure in which a plurality of display layers are stacked on the first medium side may also be employed. Alternatively, a configuration in which a plurality of display layers are provided on the first medium side and a single display layer is provided on the second medium side may be employed.
One configuration example of this embodiment is shown in FIG. FIG. 3 shows a case where d = 3.

FIG. 3 is a cross-sectional view showing a configuration example in the second embodiment of the electrochromic display element according to the present invention.
As shown in FIG. 3, in the electrochromic display element 300, at least the counter electrode 12, the reflective layer 13, the first display layer 14 including the electrochromic composition, and the first display electrode 15 are stacked in this order on the counter substrate 11. Included in the first medium 10, the second display electrode 22 on the display substrate 21, and the second display layer 23a and the second display layer 23a containing an electrochromic composition that develops a color different from that of the first display layer 14. A third display comprising an electrochromic composition having at least one of a color development threshold voltage, a decoloration threshold voltage, a charge amount necessary for color development, a charge amount necessary for decolorization, and a color to be developed different from the electrochromic composition to be developed A second medium 20B in which the layers 23b are stacked in this order, the main surface of the first medium 10 on the first display electrode 15 side, and the third display layer 2 of the second medium 20B. And b-side of the main surface opposed at intervals, in which the electrolyte 30 is filled in between two media.

  The distance between the main surface of the first medium 10 on the first display electrode 15 side and the main surface of the second medium 20B on the third display layer 23b side is a spacer provided between the counter substrate 11 and the display substrate 21. 40.

(Display operation of electrochromic display element 300)
In the electrochromic display element 300, when a desired voltage is applied between the first display electrode 15 and the counter electrode 12, the electrochromic compound contained in the first display layer 14 that is in contact with the first display electrode 15 is colored / Can be decolored. At this time, the first display electrode 15, the second display electrode 22, the second display layer 23a, and the third display layer 23b are not in contact with each other, so that no charge transfer occurs, and the second display layer 23a and the third display layer 23b does not react at all.

  On the other hand, when a desired voltage is applied between the second display electrode 22 and the counter electrode 12, the electrochromic compound contained in the second display layer 23a and the third display layer 23b in contact with the second display electrode 22 is colored. / Can be erased. At this time, since the second display electrode 22, the first display electrode 15, and the first display layer 14 are not in contact with each other, charge transfer does not occur and the first display layer 14 does not react at all.

  The second display layer 23a and the third display layer 23b are different in any one of the coloring threshold voltage, the decoloring threshold voltage, the charge amount necessary for color development, and the charge amount necessary for decoloration. Therefore, the second display layer 23a and the third display layer 23b can be individually colored / decolored by changing the voltage value, current value, and application time applied to the second display electrode 22.

  Note that the present inventors have reported a multicolor display element in which display layers having different threshold voltages and charge amounts are stacked in Japanese Patent Application Laid-Open No. 2006-106669. This prior art assumes a structure in which all three display layers are stacked on a display substrate, and the difference in threshold voltage and charge amount in each layer is not so large, so a precise drive circuit is required to control the three layers. is required. On the other hand, in the present invention, since the display layers are separately laminated on the counter substrate side (first medium 10 side) and the display substrate side (second medium 20B side), the number of layers to be controlled is reduced. (In FIG. 3, the display substrate side has two layers) Control becomes easy, and driving can be performed with an inexpensive driving circuit as compared with the prior art.

Based on the above operation principle, the first display layer 14, the second display layer 23a, and the third display layer 23b can be individually colored / decolored. Further, since the electrochromic compound has a memory property, various mixed colors can be displayed using the colors of the first display layer 14, the second display layer 23a, and the third display layer 23b. If the first display layer 14, the second display layer 23a, and the third display layer 23b are made of materials that develop the three primary colors yellow, magenta, and cyan, respectively, high-quality full-color display by subtractive color mixing can be performed. is there.
As described above, according to the electrochromic display element 300, high-quality full-color display can be obtained, and the cost can be reduced as compared with the prior art.

  Here, as the display electrodes (first display electrode 15, second display electrodes 22, 22a, and third display electrode 22b) used in the electrochromic display elements 100, 200, and 300 of the present invention, it is desirable to use transparent electrodes. . Examples of the transparent electrode include metal oxide thin films such as ITO (tin-doped indium oxide), FTO (fluorine-doped tin oxide), ZnO (zinc oxide), and IZO (indium oxide / zinc oxide). As a method for forming these metal oxide thin films, the sputtering method is most efficient, and a uniform film can be formed. Other methods include applying metal oxide fine particles.

  Examples of the counter electrode 12 include metal oxide thin films such as ITO, FTO, ZnO, and IZO, conductive metal films such as zinc and platinum, and conductive films such as carbon. In the case of using a metal oxide thin film such as ITO, FTO, or ZnO, electric charges can be efficiently transferred by forming conductive particles having a large specific surface area such as tin oxide fine particles and ITO fine particles.

  The counter substrate 11 and the display substrate 21 may be made of any material such as glass or plastic. The display substrate 21 is preferably transparent, but there is no problem even if the counter substrate 11 is colored.

  As the electrochromic compound used in the present invention, either an inorganic electrochromic compound or an organic electrochromic compound may be used. Conductive polymers can also be used because they exhibit electrochromism. Examples of the inorganic electrochromic compound include tungsten oxide, molybdenum oxide, iridium oxide, and titanium oxide. Examples of the organic electrochromic compound include viologen, rare earth phthalocyanine, styryl, terephthalic acid, and the like. Examples of the conductive polymer include polypyrrole, polythiophene, polyaniline, and the like.

  Examples of the electrolyte 30 include lithium perchlorate, lithium borofluoride, tetrabutylammonium perchlorate, and tetrabutylammonium hexafluoroborate in organic solvents such as acetonitrile, propylene carbonate, N-methylpyrrolidone, dimethyl sulfoxide, and polyethylene glycol. In addition, an electrolyte such as tetrabutylammonium butylborate, a solid system such as a perfluorosulfonic acid polymer film, an ionic liquid, or a combination thereof can be used.

  The reflective layer 13 may have a mirror-like surface or a white scattering surface. However, when it is desired to display a white color close to paper such as electronic paper, it is desirable that the reflecting layer 13 is white scattered. As a white scattering system reflection layer, it is the simplest production method to disperse and apply white pigment particles in a resin. As the white pigment fine particles, particles made of a general metal oxide can be applied, and specific examples include titanium oxide, aluminum oxide, zinc oxide, silicon oxide, cesium oxide, yttrium oxide and the like.

  In the electrochromic display elements 100, 200, and 300 of the present invention, an insulating layer can be provided between the counter electrode 12 and the reflective layer 13 and / or between the reflective layer 13 and the first display layer 14. In each of the electrochromic display elements 100, 200, and 300 of the present invention, the first display layer 15 is colored by applying a voltage between the first display electrode 15 and the counter electrode 12, and thus the first display electrode 15. The counter electrode 12 should not be short-circuited. Since there is the first display layer 14 and the reflective layer 13 between the first display electrode 15 and the counter electrode 12, there is almost no possibility of short-circuiting, but the first display electrode 15 is used by using a high-power sputtering device or the like. It is conceivable that a short circuit will occur if the film is formed. Therefore, by providing an insulating layer between the first display electrode 15 and the counter electrode 12, the possibility of a short circuit can be made almost zero and the yield of device manufacturing can be improved, resulting in a reduction in cost. Note that an insulating layer cannot be provided between the first display electrode 15 and the first display layer 14 because the first display layer 14 does not develop color.

The material for the insulating layer is not particularly limited, but a material having high insulating properties, high durability, and excellent film forming properties is preferable. Particularly preferred is a material containing at least ZnS. ZnS can be formed at high speed by a sputtering method, and can be formed without damaging the display layer containing the electrochromic compound. Examples of the film containing ZnS as a main component include ZnS—SiC, ZnS—Si, and ZnS—Ge in addition to ZnS—SiO ₂ . At this time, the ZnS ratio is preferably about 50 to 90 mol% from the viewpoint of crystallinity. Particularly preferred materials are ZnS—SiO ₂ (8/2), ZnS—SiO ₂ (7/3), ZnS, ZnS—ZnO—In ₂ O ₃ —Ga ₂ O ₃ (60/23/10/7). Yes (component ratio in parentheses).

  In the electrochromic display element 200, an insulating layer can be provided between adjacent electrode / display layer stacks, that is, between the second display layer 23a and the third display electrode 22b in FIG. In the electrochromic display element 200, when the second display electrode 22a and the third display electrode 22b are short-circuited, the second display layer 23a and the third display layer 23b cannot be individually colored / decolored. Since the second display layer 23a exists between the second display electrode 22a and the third display electrode 22b, there is almost no possibility of a short circuit, but the third display electrode 22b is formed using a high-power sputtering device or the like. If you try to do so, you may be short-circuited. Therefore, by providing an insulating layer between the second display electrode 22a and the third display electrode 22b, the possibility of short-circuiting can be made almost zero and the yield of element manufacturing can be improved, resulting in a reduction in cost. It becomes.

In the electrochromic display element of the present invention, the electrochromic composition contained in the display layer is preferably composed of conductive or semiconductive fine particles carrying an organic electrochromic compound. Specifically, it is a composition structure in which an organic electrochromic compound is adsorbed on the surface of fine particles having a particle diameter of about 5 nm to 50 nm. This composition develops a color when the charge is transferred from the display electrode through the fine particles to the organic electrochromic compound (decolored by reverse movement). For this reason, it is possible to efficiently perform coloring and decoloring reactions and to reduce power consumption.
In addition, since organic electrochromic compounds can develop various colors depending on their molecular structures, high-quality color display elements can be produced.

  The conductive or semiconductive fine particles are not particularly limited as long as the organic electrochromic compound can be adsorbed, but a metal oxide is preferably used. Specific examples of conductive or semiconductive fine particles include, but are not limited to, titanium oxide, zinc oxide, tin oxide, alumina, zirconia, ceria, silica, yttria, boronia, magnesia, strontium titanate. , Potassium titanate, barium titanate, calcium titanate, calcia, ferrite, hafnia, tungsten trioxide, iron oxide, copper oxide, nickel oxide, cobalt oxide, barium oxide, strontium oxide, vanadium oxide, barium titanate, aluminosilicate Examples thereof include metal oxides mainly composed of a salt, calcium phosphate, aluminosilicate, etc. These may be used alone or in combination of two or more. Preferred examples include titanium oxide, zinc oxide, tin oxide, alumina, zirconia, zirconia, iron oxide, magnesium oxide, indium oxide, and tungsten oxide. Titanium oxide is particularly preferably used because of its electrical characteristics and physical characteristics. .

  Examples of organic electrochromic compounds include known electrochromic compounds such as viologen compounds, phthalic acid compounds, styryl compounds, phenothiazine compounds, anthraquinone compounds, pyrazoline compounds, fluoran compounds, and talocyanine compounds. Of these, viologen-based compounds are generally the most commonly used compounds because of their good color development efficiency, memory characteristics and durability. In addition, since phthalic acid compounds have an existing structure that develops three primary colors of yellow, magenta, and cyan, they are useful compounds for producing full-color display elements.

  Examples of viologen compounds include 1-Ethyl-1 '-(2-phosphonoethyl) -4,4'-bipyridinium dichloride, 1-p-cyanophenyl-1'-(2-phosphonoethyl) -4,4'-bipyridinium and dichloride, Bis (2-phosphonylethyl) -4,4′-bipyridinium dichloride, 1-Ethyl-1′-acetic acid -4,4′-bipyridinium dichloride, and the like.

  Examples of the phthalic acid compounds include 3- (4- (methoxycarbonyl) phenyl) -3-oxopropylphosphonic acid, 3- (4 '-(methoxycarbonyl) biphenyl-4-yl) -3-oxopropylphosphonic acid, 3- (4 -acetylphenyl) -3-oxopropylphosphonic acid.

  Examples of the styryl compound include 2- [2- [4- (dimethylamino) -5-carboxy-phenyl] ethenyl] -3,3-dimethylindolino [2,1-b] oxazolidine, 2- [2- [ 4- (dimethylamino) -5-carboxy-phenyl] -1,3-butadienyl] -3,3-dimethylindolino [2,1-b] oxazolidine, 2- [2- [4- (dimethylamino) phenyl] -1, 3-butadienyl] -3,3-dimethyl-5-sulfonylindolino [2,1-b] oxazolidine, and the like.

  Examples of the phenothiazine-based compound include (2-Phenothiazin-10-yl-ethyl) -phosphinic acid, 3-Phenothiazin-10-yl-propionic acid, 3-Phenothiazin-10-yl-methanesuffonic acid, and the like. .

  In addition, the organic electrochromic compound needs to have an adsorption site in order to be supported on the surface of the conductive or semiconductive fine particles. As the adsorption site, an acidic structure such as phosphonic acid, carboxylic acid, sulfonic acid, and salicylic acid is good. In particular, the phosphonic acid structure is the most useful structure because it has a strong adsorption ability. Or you may couple | bond with the surface of electroconductive or semiconductive fine particle using a silane coupling agent etc.

The electrochromic display element according to the present invention may be performed, for example, by the following procedure. Here, a manufacturing procedure of the electrochromic display element 100 shown in FIG. 1 will be described.
(S11) First, the counter electrode 12 is formed on the counter substrate 11 by vacuum film formation such as vapor deposition, sputtering, or ion plating.
(S12) Next, the reflective layer 13 is formed on the counter electrode 12 by applying a resin in which white pigment particles are dispersed.
(S13) Next, the first display layer 14 made of an electrochromic compound and metal oxide particles is formed on the reflective layer 13 by spin coating or screen printing. That is, a liquid coating ink in which metal oxide particles and an electrochromic compound are dispersed or dissolved in a solvent is prepared, and the coating ink is spin-coated on the reflective layer 13 to form the first display layer 14. Alternatively, the first display layer 14 is formed by screen printing the coating ink on the reflective layer 13. A known solvent (for example, water, alcohol, cellosolve, halogenated carbon, ketone, ether, etc.) can be used as a solvent for adjusting the coating ink. In addition, the method for applying the first display layer 14 is not only a method of applying at once using a coating ink in which an electrochromic compound and metal oxide particles are mixed, but also applying a metal oxide particle dispersion, and thereafter It is also possible to apply the electrochromic compound on the metal oxide particle dispersion.
(S <b> 14) Next, the first display electrode 15 is formed on the first display layer 14 by vacuum film formation such as vapor deposition, sputtering, or ion plating, and the first medium 10 is obtained.

(S15) Next, the second display electrode 22 is formed on the display substrate 21 by vacuum film formation such as vapor deposition, sputtering, or ion plating.
(S16) Next, the second display layer 23 is formed on the second display electrode 22 by the same method as in step S13, and the second medium 20 is obtained.

(S17) Finally, the first medium 10 and the second medium 20 are bonded together. Specifically, a predetermined interval is provided through the main surface on the first display electrode 15 side of the outermost layer of the first medium 10 and the main surface on the second display layer 23 side of the outermost layer of the second medium 20. Then, the electrochromic display element 100 is completed by sealing the injection port after the electrolyte solution is vacuum-injected into the space.

Next, the display device according to the present invention will be described.
The display device according to the present invention is characterized by using any of the electrochromic display elements 100, 200, and 300 of the present invention. The display device (display device 500) of the present invention includes a plurality of electrochromic display elements 100, 200, and 300 of the present invention as electrochromic display elements (electrochromic display elements 51) that display one pixel. is there. With the electrochromic display element of the present invention, the display device can hold display / non-display of an image for a long time. Hereinafter, a display device using the electrochromic display element 100 will be described as an example.

FIG. 4 is a cross-sectional view showing the configuration of the display device according to the present invention.
The display device 500 includes a plurality of electrochromic display elements 51, and includes a counter substrate 11 and a display substrate 21. On the counter substrate 11, the counter electrodes 12 constituting each electrochromic display element 51, A plurality of sets of the reflective layer 13, the first display layer 14, and the first display electrode 15 are provided, and the second display electrode 22 and the second display layer 23 that constitute each electrochromic display element 51 are provided on the display substrate 21. Multiple sets are provided. One set of the counter electrode 12, the reflective layer 13, the first display electrode 15, the first display layer 14, the second display electrode 22, and the second display layer 23 constitutes one electrochromic display element 51. The display device 500 that displays an image can be provided by arranging the plurality of electrochromic display elements 51 configured in this manner in a matrix in the plane of the counter substrate 11 and the display substrate 21.
By having the above configuration, the display device 500 is used as a reflective display device such as electronic paper.

Next, a driving method of the electrochromic display element 51 in the display device 500 of the present invention will be described.
The means for applying an electric field to the electrochromic display element 51 included in the display device 500 is not particularly limited. For example, a known active matrix driving type electric circuit is adopted, and a known active matrix driving method is employed. Can be driven according to Examples of the active matrix driving type electric circuit include an electric circuit in which an electrode of a thin film transistor (TFT) as an active matrix driving element is connected to the electrochromic display element 51. Since this type of electric circuit can drive each electrochromic display element 51 at a higher speed, it is possible to provide a display device 500 that can display a high-definition image at a high speed.

FIG. 5 shows an example of a driving circuit of the display device 500 of the present invention.
A display device 500 shown in FIG. 5 includes a plurality of thin film transistors 33a and 33b connected to the plurality of electrochromic display elements 51, the first display electrode 15 and the second display electrode 22 of the plurality of electrochromic display elements 51, respectively. The plurality of lateral conducting wires 34a and 34b connected to the gate electrodes of the thin film transistors 33a and 33b, and the plurality of longitudinal conducting wires 35a and 35b connected to the source electrodes of the plurality of thin film transistors 33a and 33b. Each of the drain electrodes of the plurality of thin film transistors 33 a is connected to the first display electrode 15 of the plurality of electrochromic display elements 51. Each of the drain electrodes of the plurality of thin film transistors 33 b is connected to the second display electrodes 22 of the plurality of electrochromic display elements 51. Further, the counter electrodes 12 of the plurality of electrochromic display elements 51 have a constant potential, and may be grounded, for example.

  In the image display device 30 shown in FIG. 5, when a voltage is applied to each of one of the plurality of horizontal conducting wires 34a and one of the plurality of vertical conducting wires 35a, the selected one of the horizontal conducting wires 34a. In the thin film transistor 33a connected to the selected one vertical conductor 35a, a voltage is applied to the gate electrode to turn on the thin film transistor 33a, and the resistance between the source electrode and the drain electrode is reduced. A voltage is applied to the first display electrode 15 of the electrochromic display element 51 connected to the thin film transistor 33a. As a result, the electrochromic compound of the first display layer 14 included in the electrochromic display element 51 develops a predetermined color. Similarly, when a predetermined current is supplied to each of one of the plurality of horizontal conducting wires 34b and one of the plurality of vertical conducting wires 35b, the selected second display electrode 22 and the selected one are displayed. A voltage is applied between the two counter electrodes 12, and the electrochromic compound of the second display layer 23 included in the electrochromic display element 51 develops a predetermined color. By these operations, the pixel located between the selected one display electrode (the first display electrode 15 or the second display electrode 22) and the selected one counter electrode 12 is moved to the first display layer 14. A color developed only by the electrochromic compound, a color developed only by the electrochromic compound of the second display layer 23, a color developed by the electrochromic compound of the first display layer 14 and the electrochromic compound of the second display layer 23, Color can be developed in three stages. Similarly, the first display electrode 15 and the second display electrode 22 are selected so that the color of an arbitrary pixel is changed to a predetermined color, and the selected first display electrode 15 and second display electrode 22 are selected. An arbitrary image can be displayed on the display device 500 by applying a voltage to the counter electrode 12.

  Here, in order to maintain color development for a long time, there is no low resistance portion between one display electrode selected for color development and other display electrodes and counter electrodes other than the one display electrode, It is preferably electrically insulated. By being electrically isolated, the charge injected into the electrochromic compound is released through the electrode and the low resistance portion, or the charge released from the electrochromic compound is injected through the low resistance portion and the electrode. The color retention time can be improved.

  Furthermore, when each display electrode is colored, it is preferable to apply a voltage for erasing each display electrode in advance, and then color the display layer one layer at a time by the above-described color driving method. By applying a decoloring voltage to each display electrode in advance, it is possible to initialize the charge state (redox state) of the electrochromic compound. It can be controlled with good reproducibility.

  The redox state of each display layer is an intermediate state between an oxidized state in which all electrochromic particles are completely oxidized and a reduced state in which all electrochromic particles are completely reduced. Can be controlled. By controlling to the intermediate state, the color of each display layer can be controlled to an intermediate color which is an intermediate color between color development and decoloration.

  Here, in order to control each display layer to the intermediate state, it is performed by controlling the product of the applied voltage and time applied to each display electrode corresponding to each display layer and the time (that is, the injected or discharged charge amount). . In this case, the intermediate color can be controlled by continuously changing the applied voltage and time, but the intermediate color is controlled by changing the number of times of applying a voltage pulse having a predetermined maximum voltage value and a predetermined pulse width. You can also

  As described above, the display device 500 of the present invention can display various images because the display layers including the stacked display electrodes and the electrochromic composition are arranged in a matrix on the substrate surface. Become.

  When the thin film transistor 33b is connected to the second display electrode 22 provided on the display substrate 21 side, the thin film transistor 33b is opposite to the display substrate 21 so as not to reduce the color visibility of the electrochromic display element 51. It is also possible to form the counter substrate 11 on the side.

  Further, here, in the display device 500, an example in which two display electrodes and display layers are provided (electrochromic display element 100) is shown, but a configuration in which three or more display electrodes and display layers are provided (electrochromic display element). 200), or a configuration in which three or more display layers are provided (electrochromic display element 300).

Examples of the present invention will be described below.
Example 1
The electrochromic display element 100 shown in FIG. 1 was produced, and the light emitting operation was evaluated.
(1) Production of First Medium 10 First, the first medium 10 having the configuration shown in FIG. 6 was produced. Here, a glass substrate was used as the counter substrate 11, and a carbon paste (Jujo Chemical: CH10) was applied as a counter electrode 12 to a partial region of the main surface, followed by heating and drying at 120 ° C. for 1 hour. Next, a dispersion liquid in which 50 wt% of white titanium oxide particles (Ishihara Sangyo: CR50) are dispersed in a 5 wt% polyvinyl alcohol aqueous solution (Nippon Synthetic Chemical: Z-100) is applied on the counter electrode 12 to a thickness of 20 μm. The reflective layer 13 was formed by drying at 120 ° C. for 1 hour. And after apply | coating the titanium oxide nanoparticle slurry (Showa Denko: SP210) on the reflective layer 13, it dried at 120 degreeC for 15 minutes (sample 1).
Next, Bis (2-phosphonoethyl) -4,4′-bipyridinium dichloride (hereinafter abbreviated as EC1), which is an organic electrochromic compound, is dissolved in water to prepare a 0.04M solution. EC1 was adsorbed on the surface of the titanium oxide nanoparticle layer by immersing the first display layer 14.
Finally, as shown in FIG. 6, the first display electrode 15 was formed by forming the first display electrode 15 by mask sputtering with ITO so as not to contact the counter electrode 12.

(2) Production of Second Medium 20 Next, the second medium 20 shown in FIG. 7 was produced. Here, a glass substrate was used as the display substrate 21, and the second display electrode 22 was formed by mask sputtering deposition of ITO in a partial region of the main surface. Next, a titanium oxide nanoparticle slurry (Showa Denko: SP210) was applied on the second display electrode 22 and then dried at 120 ° C. for 15 minutes (Sample 2). Subsequently, 1-p-cyanophenyl-1 ′-(2-phosphonoethyl) -4,4′-bipyridinium dichloride (hereinafter abbreviated as EC2), which is an organic electrochromic compound, is dissolved in water to prepare a 0.04M solution. By immersing the sample 2 in this aqueous solution, EC2 was adsorbed on the surface of the titanium oxide nanoparticle layer, and the second display layer 23 was formed, whereby the second medium 20 was obtained.

(3) Fabrication of electrochromic display element 100 The first medium 10 and the second medium 20 are respectively arranged such that the main surface on the first display electrode 15 side faces the main surface on the second display layer 23 side, and a 75 μm spacer 40 is formed. Then, the cells were bonded together. Next, 0.2 M of lithium perchlorate as an electrolyte was dissolved in propylene carbonate to prepare an electrolytic solution, and this electrolytic solution was injected into the space of the cell to produce an electrochromic display element 100.

(Characteristic evaluation)
The obtained electrochromic display element 100 was operated and the color development state was observed from the display substrate 21 side.
First, white was shown in a state where no voltage was applied, and the reflectance was measured to show a high value of about 60%. For this measurement, a reflected light measuring device (Otsuka Electronics: LCD5000) was used, and measurement was performed under conditions of 30 ° incidence and 0 ° light reception.
Subsequently, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, a color was developed in blue. This color is caused by the first display layer 14 being colored blue, and the second display layer 23 was not colored. Next, when a voltage of −1.0 V was sufficiently applied, the blue color disappeared and became white again.
Further, when the second display electrode 22 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 1.5 V was applied, the color was green. This color is due to the second display layer 23 being colored green, and the first display layer 14 was not colored. Next, when a voltage of −2.0 V was sufficiently applied, the green color disappeared and became white again.
In addition, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, the color developed blue. Subsequently, when the second display electrode 22 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 1.5 V was applied, the color was black. This color was attributed to the color development of the first display layer 14 and the second display layer 23.

(Example 2)
The electrochromic display element 200 shown in FIG. 2 was produced and the light emission operation was evaluated.
(1) Production of Second Medium 20A A second medium 20A shown in FIG. 8 was produced. Here, first, the second display electrode 22a and the second display layer 23a were formed on the display substrate 21 as in the first embodiment. Next, as shown in FIG. 8, the third display electrode 22b was formed by mask sputtering of ITO so as not to contact the second display electrode 22a. Next, a titanium oxide nanoparticle slurry was applied on the third display electrode 22b, and then dried at 120 ° C. for 15 minutes (Sample 3). Then, 1-phenyl-1 ′-(2-phosphonoethyl) -4,4′-bipyridinium dichloride (hereinafter abbreviated as EC3), which is an organic electrochromic compound, is dissolved in a 2.2.3.3. Tetrafluoropropanol solution. A 1 wt% solution was prepared and applied to the sample 3 by a spin coating method so as to be adsorbed to the titanium oxide nanoparticle layer to form a third display layer 23b, thereby forming the second medium 20A.

(2) Production of electrochromic display element 200 The first display electrode 15 side main surface and the third display layer 23b side main surface of the first medium 10 and the second medium 20A manufactured in Example 1 are opposed to each other. The cells were bonded together through a spacer 40 of 75 μm. Next, 0.2 M of lithium perchlorate as an electrolyte was dissolved in propylene carbonate to prepare an electrolytic solution, and this electrolytic solution was injected into the space of the cell to produce an electrochromic display element 200.

(Characteristic evaluation)
The obtained electrochromic display element 200 was operated and the color development state was observed from the display substrate 21 side.
First, white was shown in the state where no voltage was applied, and the reflectance was measured to show a high value of about 50%.
Subsequently, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, a color was developed in blue. This color is due to the first display layer 14 being colored blue, and the second display layer 23a and the third display layer 23b were not colored. Next, when a voltage of −1.0 V was sufficiently applied, the blue color disappeared and became white again.
Further, when the second display electrode 22a was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 1.5 V was applied, the color was green. This color is caused by the second display layer 23a being colored green, and the first display layer 14 and the third display layer 23b were not colored. Next, when a voltage of −2.0 V was sufficiently applied, the green color disappeared and became white again.
Further, when the third display electrode 22b was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 2.5 V was applied, the color was red. This color is caused by the third display layer 23b being colored red, and the first display layer 14 and the second display layer 23a were not colored. Next, when a voltage of -1.5 V was sufficiently applied, the red color disappeared and became white again.
In addition, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, the color developed blue. Subsequently, when the second display electrode 22a was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 1.5 V was applied, the color was black. This color is attributed to the color development of the first display layer 14 and the second display layer 23a.
Further, when the second display electrode 22a was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 1.5 V was applied, the color was green. Subsequently, when the third display electrode 22b was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 2.5 V was applied, the color was dark brown. This color is caused by the coloration of the second display layer 23a and the third display layer 23b.
In addition, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, the color developed blue. Subsequently, when the third display electrode 22b was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 2.5 V was applied, the color was dark purple. This color is attributed to the color development of the first display layer 14 and the third display layer 23b. Further, when the second display electrode 22a was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 1.5 V was applied, the color was black. This color is caused by the first display layer 14, the second display layer 23a, and the third display layer 23b being colored.

(Example 3)
The electrochromic display element 300 shown in FIG. 3 was produced, and the light emission operation was evaluated.
(1) Production of Second Medium 20B A second medium 20B shown in FIG. 9 was produced. Here, first, the second display electrode 22 and the second display layer 23a were formed on the display substrate 21 as in the first embodiment. Next, a titanium oxide nanoparticle slurry was applied on the second display layer 23a, and then dried at 120 ° C. for 15 minutes (Sample 4). Next, EC3 is dissolved in a 2.2.3.3. Tetrafluoropropanol solution to prepare a 0.1 wt% solution, which is applied to the sample 4 by spin coating to be adsorbed on the titanium oxide nanoparticle layer, and the third display layer 23b To form a second medium 20B.

(2) Production of electrochromic display element 300 In the first medium 10 and the second medium 20B produced in Example 1, the main surface on the first display electrode 15 side and the main surface on the third display layer 23b side face each other. The cells were bonded together via a spacer 40 having a thickness of 75 μm. Next, 0.2 M of lithium perchlorate, which is an electrolyte, was dissolved in propylene carbonate to prepare an electrolytic solution, and this electrolytic solution was injected into the space of the cell to produce an electrochromic display element 300.

(Characteristic evaluation)
The obtained electrochromic display element 300 was operated and the color development state was observed from the display substrate 21 side.
First, white was shown in a state where no voltage was applied, and the reflectance was measured to show a high value of about 60%.
Next, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, the color developed blue. This color is due to the first display layer 14 being colored blue, and the second display layer 23a and the third display layer 23b were not colored. Next, when a voltage of −1.0 V was sufficiently applied, the blue color disappeared and became white again.
Further, when the second display electrode 22 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 1.5 V was applied, the color was green. This color is caused by the second display layer 23a being colored green, and the first display layer 14 and the third display layer 23b were not colored. Next, when a voltage of −2.0 V was sufficiently applied, the green color disappeared and became white again.
Further, when the second display electrode 22 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 2.5 V was applied, the color was dark brown. This color is due to the fact that the second display layer 23a and the third display layer 23b were colored simultaneously, and the first display layer 14 was not colored. Next, it turned green when a voltage of -1.5 V was applied. This color is due to the fact that only the second display layer 23a is decolored and the color of the third display layer 23b remains.
In addition, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, the color developed blue. Subsequently, when the second display electrode 22 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 1.5 V was applied, the color was black. This color is attributed to the color development of the first display layer 14 and the second display layer 23a.
In addition, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, the color developed blue. Subsequently, when the second display electrode 22 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 2.5 V was applied, the color was black. This color is caused by the first display layer 14, the second display layer 23a, and the third display layer 23b being colored. Furthermore, when -1.5V was applied, it developed dark purple. This color is due to the fact that only the second display layer 23a is decolored and the first display layer 14 and the third display layer 23b remain colored.

Example 4
In Example 2, the organic electrochromic compound is 3- (4- (methoxycarbonyl) phenyl) -3-oxopropylphosphonic acid (EC4), 3- (4 '-(methoxycarbonyl) biphenyl-4-yl, which is a phthalic acid group. ) -3-oxopropylphosphonic acid (EC5) and 3- (4-acetylphenyl) -3-oxopropylphosphonic acid (EC6) were used to produce an electrochromic display element 200 under the same conditions as in Example 2. The first display layer 14 is EC4, the second display layer 23a is EC5, and the third display layer 23b is EC6.

(Characteristic evaluation)
The obtained electrochromic display element 200 was operated and the color development state was observed from the display substrate 21 side.
First, white was shown in the state where no voltage was applied, and the reflectance was measured to show a high value of about 50%.
Next, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, a magenta color was developed. This color is caused by the first display layer 14 having a magenta color, and the second display layer 23a and the third display layer 23b were not colored. Next, when a voltage of 0 V was sufficiently applied, the magenta color disappeared and became white again.
In addition, when the second display electrode 22a was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 4.5 V was applied, a yellow color was developed. This color is due to the second display layer 23a being colored yellow, and the first display layer 14 and the third display layer 23b were not colored. Next, when a voltage of 0 V was sufficiently applied, the yellow color disappeared and became white again.
Further, when the third display electrode 22b was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 4.0 V was applied, the color was developed to cyan. This color is attributed to the fact that the third display layer 23b is colored cyan, and the first display layer 14 and the second display layer 23a are not colored. Next, when a voltage of 0 V was sufficiently applied, the cyan color disappeared and became white again.
Further, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, a magenta color was developed. Subsequently, when the second display electrode 22a was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 4.5 V was applied, the color was red. This color is attributed to the color development of the first display layer 14 and the second display layer 23a.
In addition, when the second display electrode 22a was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 4.5 V was applied, a yellow color was developed. Subsequently, when the third display electrode 22b was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 4.0 V was applied, the color was green. This color is caused by the coloration of the second display layer 23a and the third display layer 23b.
Further, when the first display electrode 15 was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 3.0 V was applied, a magenta color was developed. Subsequently, when the third display electrode 22b was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 4.0 V was applied, the color was red. This color is attributed to the color development of the first display layer 14 and the third display layer 23b. Further, when the second display electrode 22a was connected to the negative electrode, the counter electrode 12 was connected to the positive electrode, and a voltage of 4.5V was applied, the color was black. This color is caused by the first display layer 14, the second display layer 23a, and the third display layer 23b being colored.
As described above, the electrochromic display element of this example was capable of full color display.

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

DESCRIPTION OF SYMBOLS 10 1st medium 11 Counter substrate 12 Counter electrode 13 Reflective layer 14 1st display layer 15 1st display electrode 16 11th display layer / electrode laminated body 20, 20A, 20B 2nd medium 21 Display substrate 22, 22a 2nd display electrode 22b 3rd display electrode 23,23a 2nd display layer 23b 3rd display layer 24,24a 21st electrode / display layer laminated body 24b 22nd electrode / display layer laminated body 30 Electrolyte 33a, 33b Thin film transistor 34a, 34b, 35a, 35b Conductor 40 Spacer 51, 100, 200, 300 Electrochromic display element 500 Display device

Claims (10)

As a display layer / electrode laminate in which a display layer containing an electrochromic composition and a display electrode are laminated in this order on a counter electrode / reflection layer laminated on a substrate, a first display layer / electrode laminate To the a-th display layer / electrode stack (a is an integer of 0 or an integer of 2 or more), and a first medium,
As an electrode / display layer laminate in which display electrodes and a display layer containing an electrochromic composition are laminated in this order on a transparent substrate, the first electrode / display layer laminate to the b electrode / display layer laminate (B is 0 or an integer greater than or equal to 2), and a second medium laminated in order.
Each of the display layers includes an electrochromic composition that develops a different color from the other display layers,
The main surface on the display electrode side of the outermost layer of the first medium and the main surface on the display layer side of the outermost layer of the second medium are arranged to face each other with an interval, and between the first medium and the second medium An electrochromic display element filled with an electrolyte.   The electrochromic display element according to claim 1, wherein all of the display electrodes are transparent electrodes.   The electrochromic according to claim 1, further comprising an insulating layer between the two adjacent display layers / electrode stacks and / or between the two adjacent electrode / display layer stacks. Display element. A first medium in which at least a counter electrode, a reflective layer, a first display layer containing an electrochromic composition, and a first display electrode are laminated in this order on a substrate;
From the second display layer to the d-th display layer (d is an integer of 3 or more) containing an electrochromic composition that develops a different color from the other display layers on the second display electrode provided on the transparent substrate. A second medium in which are stacked in order,
The electrochromic compositions in the second display layer to the d-th display layer of the second medium have at least a coloring threshold voltage, a decoloring threshold voltage, a charge amount necessary for color development, and a charge amount necessary for decoloration. Either one is different,
A main surface on the first display electrode side of the outermost layer of the first medium and a main surface on the d-th display layer side of the outermost layer of the second medium are arranged to be opposed to each other, with the first medium, An electrochromic display element comprising an electrolyte filled between two media.   The electrochromic display element according to claim 4, wherein the first display electrode and the second display electrode are transparent electrodes.   The electrochromic display element according to claim 1, further comprising an insulating layer between the counter electrode and the reflective layer and / or between the reflective layer and the first display layer.   The electrochromic display element according to any one of claims 1 to 6, wherein the electrochromic composition contains conductive or semiconductive fine particles carrying an organic electrochromic compound on a surface thereof.   The electrochromic display element according to claim 1, wherein the electrochromic composition contains a viologen-based electrochromic compound.   The electrochromic display element according to claim 1, wherein the electrochromic composition includes a phthalic acid-based electrochromic compound.   A display device comprising the electrochromic display element according to claim 1.