JP2006267834A - Electrochromic display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrochromic display device which is patterned, wherein an observer never recognizes the pattern in a decolored state. <P>SOLUTION: The electrochromic display element which has at least a display electrode made of a substrate with a transparent conductive film, a counter electrode made of a substrate with a conductive film, and an electrochromic composition is characterized in that the conductive film of the transparent electrode is patterned by a laser. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display element, and more particularly to an element configuration of a display using an electrochromic display element, and is applied to a reflective display and electronic paper.

  Electronic paper has been actively developed as an electronic medium to replace 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. Examples of the electronic paper technology proposed so far include a reflective liquid crystal element, an electrophoretic element, a toner electrophoretic element, and the like, but all have low white reflectance.

  Electrochromism is a phenomenon in which a reversible color change or a reversible color change occurs when a voltage is applied. An EC element utilizing the coloring / decoloring of an electrochromic (hereinafter sometimes abbreviated as EC) compound that causes such a phenomenon is a reflective display element, and has a high white reflectance, and a memory effect. And because it can be driven at a low voltage, it is listed as a candidate for electronic paper.

  Patent Literature 1 (Japanese Patent Publication No. 2000-506629), Patent Literature 2 (Japanese Patent Publication No. 2001-510590), Patent Literature 3 (Japanese Patent Publication No. 2003-511837), Patent Literature 4 (Japanese Patent Laid-Open No. 2002-328401) ), Patent Document 5 (Japanese Patent Publication No. 2004-537743), and Patent Document 6 (Japanese Patent Application No. 2004-265054) describe an EC element in which an organic EC compound is supported on the surface of semiconductor fine particles such as titanium oxide. is doing. It is known that this EC element can be colored and decolored very efficiently due to the surface area effect of semiconducting fine particles, and has high repeated durability.

  As a method of forming a specific pattern on these electrochromic display elements, a method of patterning by masking or the like when the semiconductor fine particles are formed on the electrode can be considered. However, the display element manufactured by such a method has a problem that a pattern is recognized depending on the presence or absence of semiconductor fine particles even when an image is erased.

JP 2000-506629 A Special table 2001-510590 gazette Japanese translation of PCT publication No. 2003-511837 JP 2002-328401 A Special table 2004-537743 gazette Japanese Patent Application No. 2004-265054 Japanese Patent Publication No. 05-039289

  The present invention has been made in view of the above-described state of the art and problems, and in an electrochromic display device patterned, an electrochromic display device that does not allow a viewer to recognize a pattern in a decolored state. The purpose is to provide.

  As a result of various studies to solve the above problems, the inventors of the present invention have at least a display electrode made of a substrate with a transparent conductive film, a counter electrode made of a substrate with a conductive film, and an electrochromic display element having an electrochromic composition. It has been found that the above-mentioned problems can be solved when the conductive film of the transparent electrode is patterned by laser.

  Therefore, the above-mentioned problem is (1) in an electrochromic display element having at least a display electrode comprising a substrate with a transparent conductive film, a counter electrode comprising a substrate with a conductive film, and an electrochromic composition, the conductive film of the transparent electrode. Is achieved by an electrochromic display element characterized by being patterned by a laser.

  In addition, the above-mentioned problem is that the electrochromic composition (2) of the present invention comprises a conductive or semiconductive fine particle supporting an organic electrochromic compound, and the display electrode has the electrochromic composition on the electrode. This is achieved by the electrochromic display element described in the item (1), which is formed.

  The above-mentioned problem is described in (2) above, wherein the primary particle size of the conductive or semiconductive fine particles supporting the organic electrochromic compound (3) of the present invention is 50 nm or less. Of the electrochromic display element.

  Further, the above-described problem is (4) in the first aspect, wherein the conductive film of the transparent electrode has a difference in resistance value, and the density gradation is formed by the difference in resistance value of the transparent electrode. ) To the electrochromic display element according to any one of (3).

  Still further, in the electrochromic according to any one of (1) to (4), the (5) patterning by the laser according to the present invention is a line patterning. Achieved by a display element.

  Still further, the above problem is (6) the electrochromic display element according to any one of (1) to (5), wherein the transparent electrode is ITO or FTO, And (7) a display device using the electrochromic display element according to any one of (1) to (6) of the present invention.

As will be understood from the following detailed and specific description, according to the present invention, in a patterned electrochromic display device, an electrochromic display element that does not allow a viewer to recognize a pattern in a decolored state. In addition, an extremely excellent effect of providing a display device is exhibited.
In particular, according to the present invention, an electrochromic display element and a display device that do not cause a viewer to recognize a pattern in a decolored state while being patterned electrochromic display devices by patterning with a laser. An extremely excellent effect is provided.

  The electrochromic display element of the present invention will be described in detail and specifically below. The electrochromic display element of the present invention is characterized by at least a display electrode comprising a substrate with a transparent conductive film, a counter electrode comprising a substrate with a conductive film, and an electrochromic display element having an electrochromic composition, wherein the conductive film of the transparent electrode is An electrochromic display element characterized by being patterned by a laser.

  Any laser can be used as long as it changes the resistance of the transparent conductive film directly by irradiation of the transparent conductive film or indirectly by irradiation of the adjacent layer of the transparent conductive film. Laser, excimer laser marker, carbon monoxide laser, semiconductor laser, HF laser, iodine laser, glass laser, YLF laser, Alexandrite laser, semiconductor laser, dye laser, nitrogen laser, X-ray laser, free electron laser, etc. A laser can be used. The patterning method may be pattern formation by masking or pattern formation by scanning.

  In the electrochromic display element of the present invention, the electrochromic composition is one in which an organic electrochromic compound is supported on conductive or semiconductive fine particles, and the display electrode is formed by forming the electrochromic composition on the electrode. In this case, since the diffusion of the coloring material is limited, the electrochromic display element of the present invention can cope with higher definition patterning.

  Furthermore, if the average primary particle diameter of the conductive or semiconductive fine particles used in the electrochromic device of the present invention is 50 nm or less, the specific surface area of the fine particles is sufficiently large, that is, more chromophores can be adsorbed or bound. Further, since the light transmittance is greatly improved, the electrochromic device of the present invention is excellent in color development.

  The conductive or semiconductive fine particles used in the electrochromic display element of the present invention are not particularly limited as long as the organic electrochromic compound can be adsorbed thereon, but the metal is suitable for the characteristics as an electrochromic element. An 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 salt, niobium oxide, calcium phosphate, aluminosilicate, and the like. 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 the organic EC compound include, but are not limited to, viologen compounds, styryl compounds, phenothiazine compounds, anthraquinone compounds, pyrazoline compounds, fluoran compounds, talocyanine compounds, and the like. Among these, it is preferable to use a viologen-based compound because it has a reduction coloring property and can develop many colors depending on the molecular structure.

  In addition, it is preferable to have an adsorption site for supporting the fine particle surface. Adsorption sites include phosphonic acid (phosphonyl group), carboxylic acid (carboxyl group), sulfonic acid (sulfonyl group), salicylic acid (salicyl group) and other acidic structures, especially phosphonic acid structure has strong adsorption ability. Useful structure. The reflective display element of the present invention can also carry a plurality of types of organic EC compounds on conductive or semiconductive fine particles.

  Organic EC compounds such as viologen compounds can produce various colors depending on their molecular structure. Since the display element of the present invention can easily carry a plurality of types of compounds, for example, a dark purple (substantially black) color can be developed by simultaneously carrying a blue color developing compound and a red color developing compound. There are advantages such as an increase in color variations and the ability to display black with high visibility.

Further, the transparent electrode patterned with the conductive film of the present invention can express gradation without performing control by voltage or current when the pattern has a different resistance value depending on the part, and is simpler. The configuration, that is, the weight and size can be reduced.
In addition, the electrochromic display element of the present invention can be easily matrix driven by a combination with the counter electrode pattern when the conductive film of the display electrode is patterned on the line.

Examples of the transparent electrode substrate used in the electrochromic display element of the present invention include glass and plastic films. In particular, if a plastic film is used, a lightweight and flexible display device can be manufactured. As the transparent electrode film, general-purpose known transparent electrode films such as indium oxide, tin oxide, and zinc oxide can be used, but ITO or FTO is preferable in terms of resistance and transparency.
As the counter electrode, a conductive film may be formed on a substrate such as a crow or a plastic, but the substrate itself may be conductive like a metal plate.

EXAMPLES Hereinafter, the present invention will be described specifically and in detail with reference to examples, but these examples are for explaining the present invention and are not intended to limit the scope of the present invention.
[Example 1]
[Patterning of transparent electrode]
A carbon dioxide laser (beam diameter 200 μm, pulse width pulse width 20 μs, pulse frequency 24 kHz) on a part (5 × 5 mm square) of a glass substrate with tin oxide transparent electrode doped with fluorine (50 × 50 mm, about 40 Ω / cm) And an average output energy of 60 W and a wavelength of 10.6 μm) were repeatedly irradiated until the resistance value of the irradiated portion reached 1 kΩ / cm or more.

[Preparation of fine particle dispersion]
As the conductive or semiconductive fine particles, titanium oxide fine particles having a primary particle diameter of 6 nm (TKS-203 manufactured by TEIKA CORPORATION) were used. This was prepared according to the following formulation to obtain a titanium oxide paste.
Titanium oxide fine particle 20wt% dispersion (TKS-203, manufactured by Teika Co., Ltd.) 10g
Polyethylene glycol 0.7g
The above was mixed and stirred to obtain a fine particle dispersion.

[Display electrodes]
As the organic EC compound, 1-ethyl-1 ′-(3-phosphonopropyl) -4,4′-bipyridinium dichloride (hereinafter abbreviated as EC1) was used. EC1 is known and can be prepared by known methods described in Solar Energy Materials and Sollar Cells, 57, (1999), 107-125.
The display electrode was produced as follows. The above-prepared titanium oxide paste was applied to the substrate prepared above to a thickness of about 2 μm by spin coating and sintered at 400 ° C. for 1 hour. EC1 was dissolved in water to prepare a solution of 0.04 M, and EC1 was adsorbed by immersing the display electrode in this aqueous solution.

[Counter electrode]
The counter electrode has a thickness of about 2 μm by spin coating on a glass substrate on which a tin oxide transparent electrode film is attached to the entire surface of a 20 wt% aqueous dispersion of tin oxide particles (manufactured by Mitsubishi Materials Corporation) having a primary particle size of 30 nm. It was produced by applying such a method and sintering at 400 ° C. for 1 hour.

[Production of electrochromic display elements]
The display substrate and the counter substrate were bonded to each other through a 75 μm spacer to produce a cell. Displayed by preparing an electrolyte solution by dispersing 35 wt% of titanium oxide particles (manufactured by Ishihara Sangyo Co., Ltd.) with a primary particle size of 300 nm in a solution of perchloric acid chloride dissolved in propylene carbonate in 0.2 M, and sealing it in a cell. An element was produced.

[Example 2]
An electrochromic display element of the present invention was produced in the same manner as in Example 1 except that the patterning of the transparent electrode was changed to the following method.
Carbon dioxide laser (beam diameter 200 μm, pulse width pulse width 20 μs, pulse frequency 24 kHz, average output energy 60 W on a part (5 × 5 mm square) of a glass substrate with ITO transparent electrode (50 × 50 mm, about 10 Ω / cm) , Wavelength 10.6 μm) was repeatedly irradiated until the resistance value of the irradiated portion reached 1 kΩ / cm or more.

Example 3
An electrochromic display element of the present invention was produced in the same manner as in Example 1 except that the patterning of the transparent electrode was changed to the following method.
A YAG laser (beam diameter 30 μm, pulse width 10 ms, pulse frequency) oscillated from a Xe lamp-pumped YAG laser on a glass substrate with ITO transparent electrode (50 × 50 mm, approx. 10 Ω / cm) (5 × 5 mm square) (30 Hz, average output energy 200 W, wavelength 1064 nm) was repeatedly irradiated until the resistance value of the irradiated portion reached 50 Ω / cm or more.

[Comparative Example 1]
[Patterning of transparent electrode]
The glass substrate with a tin oxide transparent electrode doped with fluorine was subjected to a mask treatment of 5 × 5 mm using a cellophane tape.
[Preparation of fine particle dispersion]
Adjustments were made in the same manner as in Example 1.
[Display electrodes]
The display electrode was produced as follows. The above-prepared substrate was coated with the titanium oxide paste to a thickness of about 2 μm by spin coating, the mask was removed, and then sintered at 400 ° C. for 1 hour. EC1 was dissolved in water to prepare a solution of 0.04M, and EC1 was adsorbed by immersing the display electrode in this aqueous solution.

[Counter electrode]
It was produced in the same manner as in Example 1.
[Production of electrochromic display elements]
It was produced in the same manner as in Example 1 using the above composition.

[Comparative Example 2]
[Patterning of transparent electrode]
The plate with ITO transparent electrode was subjected to a mask treatment of 5 × 5 mm using a cellophane tape.
[Preparation of fine particle dispersion]
Adjustments were made in the same manner as in Example 1.

[Display electrodes]
The display electrode was produced as follows. The above-prepared substrate was coated with the titanium oxide paste to a thickness of about 2 μm by spin coating, the mask was removed, and sintered at 400 ° C. for 1 hour. EC1 was dissolved in water to prepare a solution of 0.04 M, and EC1 was adsorbed by immersing the display electrode in this aqueous solution.

[Counter electrode]
It was produced in the same manner as in Example 1.
[Production of electrochromic display elements]
It was produced in the same manner as in Example 1 using the above composition.

(Characteristic evaluation)
When the display electrode was connected to the negative electrode and the counter electrode was connected to the positive electrode and a voltage of 3.0 V was applied for 1 second, only a portion of the display electrode having the fine particle layer was colored reddish purple. This color is attributed to the development of the organic electrochromic compound. When a voltage of −1.0 V was applied for 1 second, the reddish purple color disappeared and became white again.
In addition, the color development / decoloration measurement of the element was performed by irradiating diffused light using a spectrocolorimeter LCD-5000 manufactured by Otsuka Electronics Co., Ltd. For the application of voltage, a function generator FG-02 manufactured by Toho Giken Co., Ltd. was used.

[Color development test]
The results of the color development / decoloration test of each electrochromic device are shown below. However, “inside” used in Table 1 represents a portion processed by laser in the example or a portion masked in the comparative example (outside) represents the other portion.
In the third embodiment, the color density is lower than that in the first embodiment, that is, gradation expression is possible.

[Pattern hiding characteristics]
Whether or not the pattern formed on each element can be recognized at the time of image erasing was visually judged. The evaluation is as follows.
○: The pattern is not visible at all visually.
Δ: A slight pattern can be confirmed.
X: A pattern can be confirmed clearly.

Claims (7)

  An electrochromic display element having at least a display electrode comprising a substrate with a transparent conductive film, a counter electrode comprising a substrate with a conductive film, and an electrochromic composition, wherein the conductive film of the transparent electrode is patterned by a laser. Electrochromic display element.   The electrochromic composition is obtained by supporting an organic electrochromic compound on conductive or semiconductive fine particles, and the display electrode is formed by forming the electrochromic composition on the electrode. The electrochromic display element described in 1.   The electrochromic display element according to claim 2, wherein the conductive or semiconductive fine particles carrying an organic electrochromic compound have a primary particle size of 50 nm or less.   The electrochromic display element according to claim 1, wherein the conductive film of the transparent electrode has a difference in resistance value, and a density gradation is formed by the difference in resistance value of the transparent electrode.   5. The electrochromic display element according to claim 1, wherein the patterning by the laser is a line patterning.   6. The electrochromic display element according to claim 1, wherein the transparent electrode is ITO or FTO. A display device comprising the display element according to claim 1.