JP5656208B2 - Medium and display device - Google Patents

Description

  The present invention relates to a medium and a display device, and more particularly to a display device using electrochromic characteristics and a medium used therefor.

  With the spread of information processing devices such as personal computers, display devices such as liquid crystal display devices have become very important devices for displaying the processing results of the information processing devices.

  Currently, a display device using so-called electrochromic characteristics has been proposed as a new display device. The electrochromic property refers to a property in which an electrochemical redox reaction occurs when a voltage is applied, and the color of the substance reversibly changes. A display using this characteristic has the following advantages: (1) excellent in viewability, (2) large size, (3) little dependency on viewing angle, and (4) clear display. In particular, application to ultra-thin displays such as so-called electronic paper is expected.

  By the way, viologen is known as a material used for a display device using the electrochromic characteristics. In general, viologen has a remarkable color change between a colored state and a decolored state, and is considered to be a very important material in the future development of display devices using electrochromic characteristics.

  However, the viologen is certainly a useful change in color between the colored state and the decolored state, but when the voltage is applied repeatedly, the color disappears from the colored state to the decolored state. There is a problem that it becomes difficult to disappear in the process, and the remaining disappearance occurs on the electrode.

  As techniques for solving this problem, for example, there are the following Non-Patent Documents 1 to 6.

The following Non-Patent Document 1 describes a technique for devising the viologen structure, and the following Non-Patent Documents 2 and 3 confine viologen molecules in cyclodextrins and prevent the disappearance of viologen by preventing the interaction between viologens. Non-Patent Document 4 below discloses a technique for devising a supporting electrolyte, and Non-Patent Documents 5 and 6 below disclose techniques for chemically adsorbing viologen on the surface of titanium oxide nanoparticles.
J. et al. Bruink, C.I. G. A. Kregting, J.A. J. et al. Ponjee, Journal of Electrochemical Society, 124, 1854, 1977 A. Yasuda, H .; Mori, J. et al. Mizuguchi, Japan Journal of Applied Physics, 26, 1352, 1987 A. Yasuda, J .; Seto, Journal of Applied Electrochemistry, 18, 333, 1988 A. Yasuda, H .; Mori, Y .; Takehana, A .; Ohkoshi, N .; Kamiya, Journal of Applied Electrochemistry, 14, 323, 1984 D. Cummins, G.M. Boschloo, M.C. Ryan, D.C. Corr, S .; Nagaraja, D.A. Fitzmaurice, Journal of Physical Chemistry B, 104, 11449, 2000 M.M. Gratzel, Nature, 409, 575, 2001

  However, in the description of Non-Patent Document 1, the design guideline for the viologen molecule is not clear, and the synthesis requires a lot of effort. In the techniques described in Non-Patent Documents 2 and 3, in order to include a specific viologen molecule, a cyclodextrin having a specific size must be used. Is not a good solution. In the technique described in Non-Patent Document 4, there is no clear guideline for selecting a supporting electrolyte, and this selection work becomes complicated. In the techniques described in Non-Patent Documents 5 and 6, in order to chemically adsorb viologen on the surface of titanium oxide nanoparticles, a functional group for that purpose must be provided in the viologen derivative, which requires a great deal of effort for synthesis.

  In view of the above problems, an object of the present invention is to provide a display device having excellent color development and decoloring characteristics by a simpler method and a medium that can be used therefor.

  Regarding the above problems, the inventor has been diligently examining, by adding at least one of a ferrocene derivative, a hydroquinone derivative, a ferrocyanide salt, a naphthoquinone derivative, a naphthohydroquinone derivative to a display device containing a viologen derivative, It has been discovered that a display device with less coloring can be provided while maintaining excellent color-developing characteristics, and the present invention has been completed.

  That is, the medium according to one means of the present invention includes a solvent, a viologen derivative, and a supporting electrolyte, and further includes at least one of a ferrocene derivative, a hydroquinone derivative, a ferrocyan ion salt, a naphthoquinone derivative, and a naphthohydroquinone derivative.

  In addition, a display device according to another means of the present invention includes a pair of substrates, a pixel electrode formed on each of opposing surfaces of the pair of substrates, a medium layer sandwiched between the pair of substrates, The medium layer includes a solvent, a viologen derivative and a supporting electrolyte, and further includes at least one of a hydroquinone derivative, a ferrocyanine ion salt, a naphthoquinone derivative, and a ferrocene derivative.

  According to the above configuration, the present invention can provide a display device having excellent color development and decoloring characteristics with a simpler configuration.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be implemented in many different forms, and is not limited to only the embodiments described below. Moreover, in this specification, the same code | symbol is attached | subjected about the component which show | plays the same function, and the description is abbreviate | omitted.

(Embodiment 1)
FIG. 1 is a schematic view of a partial cross section of a display device according to the present embodiment. As shown in FIG. 1, the display device 1 according to this embodiment includes a pair of substrates 2a and 2b, pixel electrodes 3a and 3b formed on opposite surfaces of the pair of substrates, and a pair of substrates. One of the features is that the medium layer 4 includes a solvent, a viologen derivative, a supporting electrolyte, and a ferrocene derivative.

  In the present embodiment, the pair of substrates 2a and 2b has a function of holding the pixel electrodes 3a and 3b and the liquid layer. The material of each of the pair of substrates 2a and 2b may be the same or different, but it is preferable that at least one of the substrates 2a and 2b is made of a transparent member so that the coloration and decoloring by viologen can be seen. Although it does not necessarily limit as a material of the board | substrates 2a and 2b, For example, a glass plate, plastic sheets, such as a polyethylene terephthalate, metal plates, such as stainless steel, etc. can be used suitably, and it aims at a flexible display apparatus. In this case, it is more preferable to use a transparent or translucent plastic sheet such as polyethylene terephthalate, polycarbonate, or polymethyl methacrylate. The distance between the pair of substrates can be appropriately adjusted depending on the material used for the liquid layer, the thickness of the pixel electrode, the range of applied voltage, and the like, but is preferably approximately 10 μm to 1 cm. More preferably, it is 100 μm or more and 5 mm or less.

  In the present embodiment, the pixel electrodes 3a and 3b are formed on opposite surfaces of the pair of substrates 2a and 2b, respectively, and a predetermined voltage is applied between them to control the color development and decoloration of the viologen. be able to. An area occupied by the pixel electrode is a single pixel area, and by providing a plurality of pixel electrodes, it is possible to realize complicated image display such as characters. The shape of the pixel region may be a segment that has a shape that is desired to be displayed in advance, or may be a polygon (for example, a rectangle) that can be easily arranged in a matrix. In the case where a plurality of pixel areas are arranged in a matrix and image display is to be used in a finer display, it is preferable to provide a plurality of independent pixel electrodes for each pixel area facing a pair of substrates. From the viewpoint of facilitating, etc., it is a preferable form that one pixel electrode is a so-called common electrode common to all pixels (in this embodiment, the common electrode is a form of the pixel electrode). Here, FIG. 2 shows a conceptual diagram of an example in which a plurality of independent pixel electrodes are arranged on one of a pair of substrates. A plurality of pixel electrodes 3 a are arranged on the substrate 2 a shown in the example of FIG. 2, and each pixel electrode 3 a intersects with the plurality of scanning electrodes 31 arranged substantially in parallel with the plurality of scanning electrodes 31. Each pixel electrode is connected to a signal electrode via a switching element 33 in which a gate 331 is connected to a scan electrode, for example.

  The material of the pixel electrodes 3a and 3b is not limited as long as it is conductive and does not dissolve when a voltage is applied. For example, it is a preferable embodiment that it is a metal or a conductive metal oxide. . In the case of a metal, platinum, gold, and stainless steel and alloys thereof may be used, and the metal oxide having conductivity may be an alloy including any combination of ITO, IZO, and FTO. From the viewpoint of visibility, Translucent or transparent is a preferred embodiment.

  In the present embodiment, the medium layer 4 is a layer exhibiting so-called electrochromic characteristics, and includes at least a solvent, a viologen derivative, a supporting electrolyte, and a ferrocene derivative.

  The solvent according to the present embodiment is used to retain a viologen derivative, a supporting electrolyte, and a ferrocene derivative, and is not limited to water or an organic solvent (acetonitrile, N-methyl-2-pyrrolidone, γ-butyrolactone, polyethylene glycol, tetrahydrofuran, propylene carbonate, nitromethane, dimethylformamide, dimethyl sulfoxide, methanol, ethanol, acetic anhydride, dichloromethane) and mixed solvents thereof can be used, but the solvent is not limited. In order to maintain the viologen aggregation state efficiently when the viologen derivative is colored, it is more preferably water.

The viologen derivative according to the present embodiment includes the viologen itself, and develops or decolors by giving and receiving electrons. Specifically, the reaction shown in the following formula can be performed. In the present embodiment, the viologen derivative refers to a compound represented by the following formula (1) in a state where electrons are transferred. The viologen derivative represented by the following general formula (1) emits one electron to become a compound (colored) represented by the following formula (2), and then receives one electron and is a compound represented by the following formula (1) ( (Colorless).

In the above formulas (1) and (2), there is no limitation as long as coloring and decoloring can be performed. Specific examples of R ₁ and R ₂ include an alkyl moiety, an aryl moiety, an arylalkyl moiety, and a cyano moiety. The functional group containing either of these can be mentioned. Examples of the alkyl moiety include chain and branched hydrocarbons represented by C _n H _{2n + 1} (n = 1 to 10). Examples of the aryl moiety include a phenyl group and a naphthyl group. In addition, examples of the arylalkyl moiety include a benzyl group. R ¹ and R ² may be the same or different.

  The concentration of the viologen derivative in the medium layer 4 is not limited as long as decolorization occurs. For example, when the total weight of the solvent, the viologen derivative and the supporting electrolyte is 100 parts by weight, 0.01% by weight It is preferably 30 parts by weight or more and 30 parts by weight or less, more preferably 0.1 parts by weight or more and 5 parts by weight or less. The effect that excellent visibility can be obtained by setting it to 0.01 parts by weight or more can be obtained, and if it is 0.1 parts by weight or more, this effect becomes more remarkable. Further, when the amount is 30 parts by weight or less, there is an effect that an increase in the solution viscosity can be suppressed and a decrease in response speed can be prevented, and when the amount is 5 parts by weight or less, this effect becomes more remarkable.

The supporting electrolyte in the medium layer 4 is a layer used for forming an electric double layer when a voltage is applied and causing an electrochemical reaction, and is not limited as long as it has this function. For example, LiBr, LiCl , Li ₂ SO ₄ , LiClO ₄ , NaBr, NaCl, Na ₂ SO ₄ , NaClO ₄ , KBr, KCl, K ₂ SO ₄ , KClO ₄ , (C ₄ H ₉ ) ₄ NClO ₄ , (C ₄ H ₉ ) ₄ NBF ₄ , (C ₄ H ₉ ) ₄ NPF ₆ , (C ₂ H ₅ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ NBF ₄ , (C ₂ H ₅ ) ₄ NPF ₆ , CH ₃ COONa, HCl, H ₂ SO _4, and it is preferable to use at least one of CH ₃ COOH, among the above electrolyte from the viewpoint of chemical stability of viologen derivative, medium And more preferably a salt.

  The concentration of the supporting electrolyte is not limited, but may be 0.01 parts by weight or more and 50 parts by weight or less when the total weight of the solvent, the viologen derivative and the supporting electrolyte is 100 parts by weight. Preferably, it is 0.5 parts by weight or more and 10 parts by weight or less. When the amount is 0.01 part by weight or more, a sufficient electrochemical reaction can proceed, and when the amount is 0.5 part by weight or more, this effect becomes remarkable. Further, when the amount is 50 parts by weight or less, an increase in the solution viscosity can be suppressed, and a decrease in response speed can be avoided.

The ferrocene derivative in the medium layer refers to a compound represented by the following formula (3) including ferrocene itself. The ferrocene derivative emits one electron and becomes a compound represented by the following formula (4). The compound represented by the following formula (4) receives one electron and becomes a ferrocene derivative represented by the following formula (3) again.

In the above formula, X and Y are functional groups including any of an alkyl moiety, an aryl moiety, an arylalkyl moiety, a halogen moiety, an ether moiety, a carboxyl moiety, a cyano moiety, an amino moiety, and an ammonium moiety. May be the same or different. Examples of the alkyl moiety include chain and branched hydrocarbons represented by C _n H _{2n + 1} (n = 1 to 10). Examples of the aryl moiety include a phenyl group and a naphthyl group. In addition, examples of the arylalkyl moiety include a benzyl group.

  Further, the concentration of the ferrocene derivative is not limited as long as it has the effects described later. For example, when the total weight of the solvent, the viologen derivative and the supporting electrolyte is 100 parts by weight, 0.001 part by weight The amount is preferably 20 parts by weight or less and more preferably 0.01 parts by weight or more and 10 parts by weight or less. By making it 0.001 part by weight or more, the disappearance of the viologen can be sufficiently eliminated, and by making it 0.01 part by weight or more, this effect becomes more remarkable. Further, when the amount is 20 parts by weight or less, an increase in the solution viscosity can be suppressed and a decrease in response speed can be avoided, and when the amount is 10 parts by weight or less, this effect becomes more remarkable.

  In addition to the above configuration, the display device according to the present embodiment is also preferably provided with a spacer 5 for keeping the distance between the pair of substrates constant, for example. The spacer 5 is preferably a film-like porous body, but can also be a columnar or spherical spacer disposed between a pair of substrates. As the material of the spacer, ceramics, polymer, and cellulose can be adopted, but not limited thereto.

  Furthermore, the display device according to the present embodiment preferably includes an external power supply 6 connected to the signal electrode and the scanning electrode (indirectly the pixel electrode) in order to apply a desired voltage between the pixel electrodes. By doing so, electrons can be transferred to and from the viologen derivative and ferrocene derivative, and an image can be displayed. Although not limited as long as image display is possible, it is preferable to apply a voltage between the pair of electrodes so that an electric field of 0.01 V / cm to 10 V / cm is applied. More preferably, it is 0.1 V / cm or more and 5 V / cm or less.

  As described above, according to the display device according to the present embodiment, it is possible to provide a display device having excellent color-decoloring characteristics. This effect does not go beyond estimation, but can be considered as follows. This conceptual diagram is shown in FIG. Fig. 3 shows how the viologen derivative receives one electron (subjects to one-electron reduction), releases the electron from the state of being attached to one electrode (colored state), and leaves the electrode (decoloring process). Represents a series of conceptual diagrams.

  In the first stage, the viologen derivative is subjected to one-electron reduction and is attached to the electrode (colored). On the other hand, the ferrocene derivative is mixed and adsorbed on the electrode together with the viologen derivative. When a positive voltage is applied to the electrode, the one-electron reductant of the viologen derivative should be oxidized and return to the original state and leave the electrode, but the viologen derivative adheres to the electrode. During this time, recrystallization occurs and it is not easily oxidized. However, as shown in the figure, when a ferrocene derivative is mixed, the ferrocene derivative is first oxidized in place of the viologen one-electron reductant. (See FIGS. 3A and 3B).

  Next, the ferrocene derivative in the state where one electron has been extracted draws one electron from the adjacent viologen derivative. As a result, the viologen derivative becomes a divalent cation (FIGS. 3B and 3C).

  Then, the viologen derivative that has emitted one electron and becomes a divalent cation binds to the anion in the supporting electrolyte, and is detached from the electrode and dissolved in the medium layer (FIGS. 3C and 3D).

  In other words, the ferrocene derivative thus enters between the one-electron reductants of the viologen derivative, and chemically oxidizes the viologen derivative that is less likely to return to the original state due to crystallization on the electrode (which is less likely to be oxidized). Therefore, it is possible to prevent the disappearance remaining due to recrystallization, so that it is possible to provide a display device excellent in color development and decoloration. As described above, the display device according to the present embodiment is excellent in color development and decoloration only by adding a ferrocene derivative, and can exert an effect without largely depending on a material such as a viologen derivative or a supporting electrolyte.

(Embodiment 2)
The display device according to the present embodiment is the same as that of the first embodiment except that the ferrocene derivative of the first embodiment is a hydroquinone derivative. Hereinafter, different points will be described, and other similar points will be omitted.

The hydroquinone derivative in the liquid layer refers to a compound represented by the following formula (5). Hydroquinone emits two electrons and two hydrogen ions to become a benzoquinone represented by the following formula (6). On the other hand, benzoquinone receives two electrons and two hydrogen ions to become hydroquinone again.

In the above formula, R ₃ is a functional group including any of an alkyl moiety, an aryl moiety, an arylalkyl moiety, a halogen moiety, an ether moiety, a carboxyl moiety, a cyano moiety, an amino moiety, and an ammonium moiety. Examples of the alkyl moiety include chain and branched hydrocarbons represented by C _n H _{2n + 1} (n = 1 to 10). Examples of the aryl moiety include a phenyl group and a naphthyl group. In addition, examples of the arylalkyl moiety include a benzyl group.

  Further, the concentration of hydroquinone is not limited as long as it has the effects described later. For example, when the total weight of the solvent, the viologen derivative and the supporting electrolyte is 100 parts by weight, 0.001 part by weight The amount is preferably 20 parts by weight or less and more preferably 0.01 parts by weight or more and 10 parts by weight or less. When the amount is 0.001 part by weight or more, sufficient erasing of the viologen derivative can be achieved, and when the amount is 0.01 part by weight or more, this effect becomes more remarkable. Moreover, the rise of a solution viscosity can be suppressed by setting it as 20 weight part or less, and the fall of a response speed can be avoided, and this effect can be made more remarkable by setting it as 10 weight part or less.

  As described above, according to the display device according to the present embodiment, it is possible to provide a display device that not only has excellent color development / decoloring characteristics but also has less coloring (background color is close to white). This effect does not go beyond estimation, but can be considered as follows. This conceptual diagram is shown in FIG. Fig. 4 shows how the viologen derivative receives one electron (subjects one-electron reduction), releases the electron from the state attached to one electrode (colored state), and leaves the electrode (decoloring process). Represents a series of conceptual diagrams.

  In the first stage, the viologen derivative is subjected to one-electron reduction and is attached to the electrode (colored). On the other hand, the hydroquinone derivative is mixed and adsorbed on the electrode together with the viologen derivative. When a positive voltage is applied to the electrode, the one-electron reductant of the viologen derivative should be oxidized and return to the original state and leave the electrode, but the viologen derivative adheres to the electrode. During this time, recrystallization occurs and it is not easily oxidized. However, as shown in the figure, when a hydroquinone derivative is mixed, the hydroquinone derivative is first oxidized in place of the viologen one-electron reductant, and becomes benzoquinone and adheres to the electrode (see FIGS. 4A and 4B). . At this time, hydroquinone extracts two electrons by the electrode (two-electron oxidation).

  Then, this benzoquinone pulls out one electron at a time from two molecules of the viologen derivative, and becomes a hydroquinone derivative again (FIGS. 4B and 4C).

  Then, the viologen derivative from which two electrons are emitted becomes a divalent ion, and is separated from the electrode and dissolved in the liquid layer (FIGS. 4C and 4D).

  In other words, the hydroquinone derivative thus enters between the one-electron reductants of the viologen derivative and chemically oxidizes the viologen derivative that has become difficult to return to the original state due to crystallization on the electrode (which is less likely to be oxidized). Therefore, it is possible to prevent the disappearance remaining due to recrystallization, so that it is possible to provide a display device excellent in color development and decoloration. As described above, the display device according to the present embodiment is excellent in color development and decoloration only by adding a hydroquinone derivative, and can exert an effect without largely depending on materials such as a viologen derivative and a supporting electrolyte.

(Embodiment 3)
The display device according to this embodiment is the same as that of Embodiment 1 except that the ferrocene derivative of Embodiment 1 is a ferrocyan ion salt. Hereinafter, different points will be described, and other similar points will be omitted.

The ferrocyan ion in the liquid layer refers to a compound represented by the following formula (7), which is an alkali metal or alkaline earth metal cation (for example, K ⁺ , Na ⁺ , Li ⁺ , Ca ²⁺ etc.) and a salt. What formed is called ferrocyan ion salt. Ferrocyan ion emits one electron and becomes ferricyan ion represented by the following formula (8). On the other hand, ferricyan ion receives one electron and becomes ferrocyan ion again.

  Further, the concentration of the ferrocyan salt is not limited as long as it has the effects described later. For example, when the total weight of the solvent, the viologen derivative and the supporting electrolyte is 100 parts by weight, 0.001 The amount is preferably from 20 parts by weight to 20 parts by weight, and more preferably from 0.01 part by weight to 10 parts by weight. When the amount is 0.001 part by weight or more, sufficient erasing of the viologen derivative can be achieved, and when the amount is 0.01 part by weight or more, this effect becomes more remarkable. Further, when the amount is 20 parts by weight or less, an increase in the solution viscosity can be suppressed and a decrease in response speed can be avoided, and when the amount is 10 parts by weight or less, this effect becomes more remarkable.

  As described above, according to the display device according to the present embodiment, it is possible to provide a display device that not only has excellent color development / decoloring characteristics but also has less coloring (background color is close to white).

(Embodiment 4)
The display device according to this embodiment is the same as that of Embodiment 2 except that the hydroquinone of Embodiment 2 is changed to naphthohydroquinone. Hereinafter, different points will be described, and other descriptions will be omitted.

The naphthohydroquinone in the liquid layer refers to a compound represented by the following formula (9). Naphthohydroquinone emits two electrons and two hydrogen ions to become naphthoquinone represented by the following formula (10). On the other hand, naphthoquinone receives two electrons and two hydrogen ions, and becomes naphthohydroquinone again.

In the above formula, R ₄ and R ₅ are functional groups including any of an alkyl moiety, an aryl moiety, an arylalkyl moiety, a halogen moiety, an ether moiety, a carboxyl moiety, a cyano moiety, an amino moiety, and an ammonium moiety; ₄ and R ₅ may be the same or different. Examples of the alkyl moiety include chain and branched hydrocarbons represented by C _n H _{2n + 1} (n = 1 to 10). Examples of the aryl moiety include a phenyl group and a naphthyl group. In addition, examples of the arylalkyl moiety include a benzyl group.

  In addition, the concentration of naphthohydroquinone is not limited as long as it has the effects described below, but is not limited as long as it has the effects described below. For example, the concentration of the solvent, viologen derivative, and supporting electrolyte is not limited. When the total weight is 100 parts by weight, it is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight. When the amount is 0.001 part by weight or more, sufficient erasing of the viologen derivative can be achieved, and when the amount is 0.01 part by weight or more, this effect becomes more remarkable. Further, when the amount is 10 parts by weight or less, an increase in the solution viscosity can be suppressed and a decrease in response speed can be avoided, and when the amount is 5 parts by weight or less, this effect becomes more remarkable.

  As described above, according to the display device according to the present embodiment, it is possible to provide a display device that not only has excellent color development / decoloring characteristics but also has less coloring.

  Note that the ferrocene derivative, hydroquinone derivative, ferrocyan ion salt, naphthoquinone derivative, and naphthohydroquinone derivative described in Embodiments 1 to 4 above may be used alone or in a suitable mixture.

  Here, the effect of the display device according to the above embodiment was actually tested to confirm the effect. This result will be described below.

Example 1
First, to 20 ml of water, 7 mM of dibenzyl viologen represented by the following formula, 2 mM of ferrocene derivative represented by the following formula and LiBr as a supporting electrolyte were added to 0.1 M to prepare a medium.

(Cyclic voltammetry)
First, cyclic voltammetry (hereinafter referred to as “CV”) was performed using the apparatus shown in FIG. As shown in FIG. 5, this CV immerses a pair of electrodes in which a transparent electrode made of ITO of 15 mm × 25 mm and a metal electrode made of Pt of 10 mm × 20 mm are opposed to each other by 10 mm in a medium to apply an electric field. It was done. The voltage was changed from −0.7 V to +0.5 V with respect to the saturated calomel reference electrode (SCE) at a sweep rate of 20 mV / s and repeated 10 times. The result is shown in FIG.

  According to this result, dibenzylviologen was subjected to one-electron reduction at around −0.6 V to produce a purple one-electron reductant, deposited on the ITO electrode in a film shape, and the electrode was colored purple. Then, the electrode oxidation reaction described in FIG. 3 proceeded around +0.3 V, and the purple color on the electrode was completely erased. It was confirmed that even if the potential sweep was repeated, no deterioration or disappearance occurred, and it was confirmed that the potential was stably repeated, and a display device having excellent color development / erasing characteristics could be provided.

(Coloring efficiency measurement)
Moreover, the coloring efficiency was measured using the apparatus shown in FIG. As shown in FIG. 7, this measurement employs 30 mm × 30 mm ITO (formed on a glass substrate) and a φ0.3 mm Au wire as a pair of electrodes, which are spaced apart by about 20 mm, and the above-mentioned size is measured. It was performed by immersing in the same medium as used in click voltammetry and measuring the absorbance and the amount of energized electricity when a potential of -0.7 V was applied. In this measurement, the coloring efficiency means the absorbance changed with respect to the unit energization electricity, and the absorbance at a wavelength of 553 nm (maximum absorption wavelength of a viologen one-electron reductant) is adopted. FIG. 8 shows the relationship between the amount of electricity supplied and the absorbance obtained by this measurement. The slope of this plot corresponds to the coloring efficiency.

As a result, a value of 120 cm ² / C was obtained as the coloring efficiency. This value was almost inferior to the coloring efficiency of 130 cm ² / C of the dibenzyl viologen alone system not containing the ferrocene derivative, and it was confirmed that the addition of the ferrocene derivative does not hinder the coloring process.

(Example 2)
First, the medium is immersed between a pair of glass substrates, a glass plate (opposite electrode) having a 25 mm × 30 mm ITO formed on the entire surface and a glass plate (display electrode) having a 25 mm × 30 mm ITO pattern formed thereon. A porous spacer (thickness: 400 μm) was sandwiched and the periphery was sealed with an epoxy resin. Next, a voltage of -1.2 V was applied to the counter electrode on the display electrode side, and purple color development of dibenzylviologen was confirmed on the ITO pattern. Then, on the display electrode side, a voltage of +1.2 V was applied to the counter electrode, and it was confirmed that the purple color on the ITO pattern disappeared, and it was confirmed that the display device was excellent in color development and decoloration. It was.

Example 3
First, to 20 ml of water, 7 mM of benzyl viologen, 2 mM of a ferrocene derivative represented by the following formula was added, and LiBr as a supporting electrolyte was added to 0.1 M to prepare a medium.

(Cyclic voltammetry)
The same conditions as in Example 1 were used except that the above medium was used. The voltage was changed from −0.7 V to +0.8 V with respect to SCE at a sweep rate of 20 mV / s, and was repeated 10 times. The result is shown in FIG.

  According to this result, dibenzylviologen was subjected to one-electron reduction at around −0.6 V to produce a purple one-electron reductant, deposited on the ITO electrode in a film shape, and the electrode was colored purple. The electrode oxidation reaction proceeded around +0.6 V, and the purple color on the electrode was completely erased. It was confirmed that even if the potential sweep was repeated, there was no deterioration or disappearance, and it was confirmed that the potential was stably repeated, and it was possible to provide a display device and its medium having excellent color-decoloring characteristics. .

(Coloring efficiency measurement)
Coloring efficiency was measured using the same conditions and the same measuring apparatus as in Example 1 except that the above medium was used. The result is shown in FIG. As a result, a value of 130 cm ² / C was obtained as the coloring efficiency. This value is the same value as the coloring efficiency of 130 cm ² / C of the dibenzyl viologen alone system not containing the ferrocene derivative, and it was confirmed that the addition of the ferrocene derivative does not hinder the coloring process.

Example 4
In addition, a display device having the same size as that of Example 2 was produced, and the color development / erasure was confirmed. The medium used in this example was the same as the medium manufactured in Experimental Example 3. On the display electrode side, a voltage of -1.5 V was applied to the counter electrode, and purple color development of dibenzylviologen was confirmed on the ITO pattern. Then, on the display electrode side, a voltage of +1.5 V was applied to the counter electrode, and it was confirmed that the purple color on the ITO pattern disappeared, and it was confirmed that the display device was excellent in color development and decoloration. It was.

(Example 5)
First, to 20 ml of water, 7 mM of viologen, 2 mM of hydroquinone, and LiBr as a supporting electrolyte were added to a concentration of 0.1 M to prepare a medium.

(Cyclic voltammetry)
CV was performed using the same conditions and the same apparatus as Example 1 except having used said medium. The voltage was changed between −0.75 V and 0.4 V at a sweep rate of 20 mV / s and repeated 10 times. The result is shown in FIG.

  According to this result, dibenzylviologen was subjected to one-electron reduction at around −0.6 V to produce a purple one-electron reductant, deposited on the ITO electrode in a film shape, and the electrode was colored purple. The electrode oxidation reaction proceeded around +0.2 V, and the purple color on the electrode was completely erased. It was confirmed that even if the potential sweep was repeated, there was no deterioration or disappearance, and it was confirmed that the potential was stably repeated, and it was possible to provide a display device and its medium having excellent color-decoloring characteristics. .

(Coloring efficiency measurement)
Coloring efficiency was measured using the same measurement apparatus and the same conditions as in Example 1 except that the above medium was used. The result is shown in FIG.

According to this result, a value of 160 cm ² / C was obtained as the coloring efficiency. This value is a value that exceeds the coloring efficiency of 130 cm ² / C of the dibenzyl viologen alone system that does not contain the ferrocene derivative, and hydroquinone not only contributes to the disappearance of the decoloring process but also improves the coloring efficiency. It was confirmed.

(Example 6)
In addition, a display device having the same size as that of Example 2 was produced, and the color development / erasure was confirmed. The medium used in this example was the same as the medium manufactured in Experimental Example 5. On the display electrode side, a voltage of −1.1 V was applied to the counter electrode, and purple color development of dibenzylviologen was confirmed on the ITO pattern. Then, on the display electrode side, a voltage of +1.1 V was applied to the counter electrode, and it was confirmed that the purple color on the ITO pattern disappeared, and it was confirmed that the display device was excellent in color development and decoloration. It was.

  As described above, it has been confirmed from this experimental example and example that it is possible to provide a display device having excellent color development and decoloring characteristics by using this principle. In particular, the hydroquinone in this example is colorless and transparent, and is particularly useful with almost no coloring of the background of the device.

(Example 7)
First, to 20 ml of water, viologen was added to 7 mM, potassium ferrocyanide represented by the following formula was added to 2 mM, and LiBr as a supporting electrolyte was added to 0.1 M to prepare a medium.

(Cyclic voltammetry)
CV was performed using the same conditions and the same apparatus except using the above medium. The voltage was changed between −0.75 V and +0.6 V at a sweep rate of 20 mV / s and repeated 10 times. The result is shown in FIG.

  According to this result, dibenzylviologen was subjected to one-electron reduction at around −0.6 V to produce a purple one-electron reductant, deposited on the ITO electrode in a film shape, and the electrode was colored purple. The electrode oxidation reaction proceeded around +0.2 V, and the purple color on the electrode was completely erased. It was confirmed that even if the potential sweep was repeated, there was no deterioration or disappearance, and it was confirmed that the potential was stably repeated, and it was possible to provide a display device and its medium having excellent color-decoloring characteristics. .

(Coloring efficiency measurement)
Further, the coloring efficiency was measured in the same manner as in Experimental Example 3. The medium used in this experimental example is the same as the above CV, and the apparatus used is the same as in the above experimental example 2. The result is shown in FIG.

According to this result, a value of 230 cm ² / C was obtained as the coloring efficiency. This value is a value that exceeds the coloring efficiency of 130 cm ² / C of the dibenzyl viologen alone system that does not contain the ferrocene derivative, and the ferrocyanic ion not only contributes to the elimination of the disappearance of the decoloring process, but also has the coloring efficiency. Confirmed to improve.

(Example 8)
In addition, a display device having the same size as that of Example 2 was produced, and the color development / erasure was confirmed. The medium used in this example was the same as the medium manufactured in Experimental Example 5. On the display electrode side, a voltage of −1.1 V was applied to the counter electrode, and purple color development of dibenzylviologen was confirmed on the ITO pattern. Then, on the display electrode side, a voltage of +1.1 V was applied to the counter electrode, and it was confirmed that the purple color on the ITO pattern disappeared, and it was confirmed that the display device was excellent in color development and decoloration. It was.

  As described above, it has been confirmed from this experimental example and example that it is possible to provide a display device having excellent color development and decoloring characteristics by using this principle.

  The present invention relates to a display device and has industrial applicability.

1 is a schematic diagram of a partial cross section of a display device according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating an example of electrodes on one substrate of the display device according to the first embodiment. FIG. 3 is a diagram illustrating an outline of an operation estimated in the display device according to the first embodiment. FIG. 10 is a diagram illustrating an outline of an operation estimated in the display device according to the second embodiment. It is a figure which shows the outline of the CV apparatus in Example 1. FIG. It is a figure which shows the result of CV in Example 1. FIG. 1 is a diagram showing an outline of an apparatus for measuring coloring efficiency in Example 1. FIG. It is a figure which shows the result of the coloring efficiency measurement in Example 1. FIG. It is a figure which shows the result of CV in Example 3. FIG. It is a figure which shows the result of the coloring efficiency measurement in Example 3. It is a figure which shows the result of CV in Example 5. FIG. It is a figure which shows the result of the coloring efficiency measurement in Example 5. It is a figure which shows the result of CV in Example 7. FIG. It is a figure which shows the result of the coloring efficiency measurement in Example 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 2a, 2b ... Substrate, 3a, 3b ... Pixel electrode, 4 ... Medium layer, 5 ... Spacer

Claims (6)

An electrochromic display medium comprising a solvent containing water, a viologen derivative and a supporting electrolyte, and further comprising a ferrocene derivative having a surface active group represented by the following formula .
(In the above formulas, X and Y are functional groups including any of alkyl, aryl, halogen, ether, carboxyl, cyano, amino and ammonium moieties, and X and Y are the same. Or it may be different.) The electrochromic display medium according to claim 1, comprising the viologen derivative represented by the following formula.
(In the above formula, R ₁ and R ₂ are functional groups including any of an alkyl moiety, an aryl moiety, a halogen moiety, an ether moiety, a carboxyl moiety, a cyano moiety, an amino moiety, and an ammonium moiety, and R ₁ and R ₂ Can be the same or different.) An electrochromic display medium comprising a solvent containing water, a viologen derivative and a supporting electrolyte, and further comprising a ferrocene derivative having a surface active group ,
The solvent is viologen derivative and when a total of 100 parts by weight of supporting electrolyte, contrary including the ferrocene derivative 0.001 part by weight or more than 20 parts by weight, elect runner electrochromic display medium. A pair of substrates;
A pixel electrode formed on each of the opposing surfaces of the pair of substrates;
An electrochromic display medium layer sandwiched between the pair of substrates, and a display device comprising:
The electrochromic display medium layer is a water-containing solvent comprises a viologen derivative and a supporting electrolyte, further including a ferrocene derivative represented by the following formula having a surface active group, the display apparatus.
(In the above formulas, X and Y are functional groups including any of alkyl, aryl, halogen, ether, carboxyl, cyano, amino and ammonium moieties, and X and Y are the same. Or it may be different.) The display device according to claim 4 , wherein the electrochromic display medium layer includes the viologen derivative represented by the following formula.
(In the above formula, R ₁ and R ₂ are functional groups including any of an alkyl moiety, an aryl moiety, a halogen moiety, an ether moiety, a carboxyl moiety, a cyano moiety, an amino moiety, and an ammonium moiety, and R ₁ and R ₂ Can be the same or different.) A pair of substrates;
A pixel electrode formed on each of the opposing surfaces of the pair of substrates;
An electrochromic display medium layer sandwiched between the pair of substrates.
A device,
The electrochromic display medium layer includes a solvent containing water, a viologen derivative and a supporting electrolyte, and further includes a ferrocene derivative having a surface active group, and the total of the solvent, the viologen derivative and the supporting electrolyte is 100 parts by weight. If, contrary including the ferrocene derivative 0.001 part by weight or more and 20 parts by weight or less, the display apparatus.